Bill
:Bill
:
On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
Lewis
::Bill
::
:
:
:
:
:On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:Lewis
:
I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
Bill
:::Bill
:::
::
::
::
::
::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
::Lewis
::
:
:Thanks Lewis,
:I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
:Bill
:
Lewis
Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
Norm
::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
::::Bill
::::
:::
:::
:::
:::
:::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::Lewis
:::
::
::Thanks Lewis,
::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::Bill
::
:
:
:
:I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:Lewis
:
Bill
:Hi
:
: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
:
: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
:
: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
:
:http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
:
:Norm
:
:::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
:::::Bill
:::::
::::
::::
::::
::::
::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
::::Lewis
::::
:::
:::Thanks Lewis,
:::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
:::Bill
:::
::
::
::
::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
::Lewis
::
:
:Bill
:
::Hi
::
:: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
::
:: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
::
:: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
::
::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
::
::Norm
::
::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
::::::Bill
::::::
:::::
:::::
:::::
:::::
:::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::::Lewis
:::::
::::
::::Thanks Lewis,
::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::::Bill
::::
:::
:::
:::
:::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:::Lewis
:::
::
:
So four filtering caps are being involved. Standing by . . . . . for test data to see direction of approach for further analysis. ::Norm, the tubes tested on 533A. I can test them again. No 24A in place of 35. Tho I had thought about trying one. So thanks for the warning. The strongest station around here is 820 and it is very close. It does cause the most meter deflection but less than 1/8 inch movement. No problem with reading the resistor value as all old dogbone type were clearly marked. ::: :::::: :::::Thanks Lewis,
Sir Bill. . . . . .from VA
That sets metering is dependent upon the current consumption of the 1st two RF tubes, the B+ supply level and the grid biasing being supplied to them via the developed AVC.
And I am blind on the scale length of the metering scale of the unit, so lets just hereafter be referring as a percentage of meter full scale deflection.
Now the B+ coming in to the low side of the metring seems to be a fixed factor and is coming in at quite a hefty level, in the respect of not having incorporating any high value series dropping resistor(s).
Not exactly sure on the magnetic field retentivity of old metering , with it not having been specifically designed for more critical intrumentation uses.
Now that meters in circuit tuning action range, we . . . CAN . . .evaluate.
To initially establish that , refer to my post of:
http://www.nostalgiaair.org/Forums/Messages/390/M0086390.htm
Which is a stand alone troubleshooting sequence relevant to tuning eye problems and you merely have an electro-mechanical variant here with the RF tubes plate current consumption being the indicator of metering.
Refer to the end schematic and the [Pale Yellow] inset of the building up of a test bias supply.
Build up that same circuitry and then lets locate the place that you need to connect.
Since I am now at a site that leaves me naked of my schematic / drawing facilities, let me have you find the
very noticable pair of .05 caps that are just lower left of the pilot lamp on the schema.
We are interrested in the junction of the bottom .05 and the 100K above it and the AVC buss wiring which
then flows over to the left to feed those RF tubes grid that I mentioned.
Now in the interim you have four potential problem childs in the respect of those two .05 caps leaking to ground and bleeeeeding down your hard earned AVC voltage . . . . along with two other dudes off to the left that are tied in to the two 100k resistors off from this buss that feed into the mixer stage where you see another .05 to ground being used there and over to the left at the RF stage it looks to be a .047 to ground being used there.
Tolerate ZERO leakage from those components.
Now for the test . . . . connect the bias supply output resistor to the AVC buss at the very first junction that
I had initially mentioned .
Have the pot setting for putting out max negative voltage and observe the metering and give us that reading as its being proportional of a full scale reading.
Reverse the bias supply leads and introduce POSITIVE voltage to the AVC buss for just long enough time to establish a reading and give us the percentage of full scale.
73's de Edd
::Bill
::
:::Hi
:::
::: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
:::
::: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
:::
::: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
:::
:::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
:::
:::Norm
:::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
:::::::Bill
:::::::
::::::
::::::
::::::
::::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
::::::Lewis
::::::
:::::
:::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
:::::Bill
:::::
::::
::::
::::
::::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
::::Lewis
::::
:::
::
:
:
:
:
: : : : : : : : : : :Sir Bill. . . . . .from VA : : :That sets metering is dependent upon the current consumption of the 1st two RF tubes, the B+ supply level and the grid biasing being supplied to them via the developed AVC. : : :And I am blind on the scale length of the metering scale of the unit, so lets just hereafter be referring as a percentage of meter full scale deflection. : : :Now the B+ coming in to the low side of the metring seems to be a fixed factor and is coming in at quite a hefty level, in the respect of not having incorporating any high value series dropping resistor(s). : : :Not exactly sure on the magnetic field retentivity of old metering , with it not having been specifically designed for more critical intrumentation uses. : : :Now that meters in circuit tuning action range, we . . . CAN . . .evaluate. : : :To initially establish that , refer to my post of: : : :http://www.nostalgiaair.org/Forums/Messages/390/M0086390.htm : : :Which is a stand alone troubleshooting sequence relevant to tuning eye problems and you merely have an electro-mechanical variant here with the RF tubes plate current consumption being the indicator of metering. : : :Refer to the end schematic and the [Pale Yellow] inset of the building up of a test bias supply. : : :Build up that same circuitry and then lets locate the place that you need to connect. : : :Since I am now at a site that leaves me naked of my schematic / drawing facilities, let me have you find the : very noticable pair of .05 caps that are just lower left of the pilot lamp on the schema. : : :We are interrested in the junction of the bottom .05 and the 100K above it and the AVC buss wiring which :then flows over to the left to feed those RF tubes grid that I mentioned. : : :Now in the interim you have four potential problem childs in the respect of those two .05 caps leaking to ground and bleeeeeding down your hard earned AVC voltage . . . . along with two other dudes off to the left that are tied in to the two 100k resistors off from this buss that feed into the mixer stage where you see another .05 to ground being used there and over to the left at the RF stage it looks to be a .047 to ground being used there. : : So four filtering caps are being involved. :Tolerate ZERO leakage from those components. : : :Now for the test . . . . connect the bias supply output resistor to the AVC buss at the very first junction that :I had initially mentioned . : : :Have the pot setting for putting out max negative voltage and observe the metering and give us that reading as its being proportional of a full scale reading. : : :Reverse the bias supply leads and introduce POSITIVE voltage to the AVC buss for just long enough time to establish a reading and give us the percentage of full scale. : : : :Standing by . . . . . for test data to see direction of approach for further analysis. : : : : : : :73's de Edd Thanks Edd, : |
:
:
:
:
:
:
:
:
:
:::Norm, the tubes tested on 533A. I can test them again. No 24A in place of 35. Tho I had thought about trying one. So thanks for the warning. The strongest station around here is 820 and it is very close. It does cause the most meter deflection but less than 1/8 inch movement. No problem with reading the resistor value as all old dogbone type were clearly marked.
:::Bill
:::
:
:
:
:
::::Hi
::::
:::: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
::::
:::: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
::::
:::: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
::::
::::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
::::
::::Norm
:
:
:
:
:
:
::::
::::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
::::::::Bill
::::::::
:::::::
:::::::
:::::::
:
:
:
:
:
:::::::
:::::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::::::Lewis
:::::::
::::::
:
:
:
:
::::::Thanks Lewis,
::::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::::::Bill
::::::
:::::
:::::
:
:
:
:
:
:::::
:::::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:::::Lewis
:::::
::::
:::
::
:
I'm back a little early so I worked up the meter deflections. I didn't mention it but the meter pointer in the off position is on the right side of meter. When set is turned on it assumes the position in the first picture. The second picture is with negative voltage, and the third is positive voltage. Thanks very much for your help.
Bill
:
:
:
:
:
:
:
:
:
:
:
:
:
:Sir Bill. . . . . .from VA
:
:
:That sets metering is dependent upon the current consumption of the 1st two RF tubes, the B+ supply level and the grid biasing being supplied to them via the developed AVC.
:
:
:And I am blind on the scale length of the metering scale of the unit, so lets just hereafter be referring as a percentage of meter full scale deflection.
:
:
:Now the B+ coming in to the low side of the metring seems to be a fixed factor and is coming in at quite a hefty level, in the respect of not having incorporating any high value series dropping resistor(s).
:
:
:Not exactly sure on the magnetic field retentivity of old metering , with it not having been specifically designed for more critical intrumentation uses.
:
:
:Now that meters in circuit tuning action range, we . . . CAN . . .evaluate.
:
:
:To initially establish that , refer to my post of:
:
:
:http://www.nostalgiaair.org/Forums/Messages/390/M0086390.htm
:
:
:Which is a stand alone troubleshooting sequence relevant to tuning eye problems and you merely have an electro-mechanical variant here with the RF tubes plate current consumption being the indicator of metering.
:
:
:Refer to the end schematic and the [Pale Yellow] inset of the building up of a test bias supply.
:
:
:Build up that same circuitry and then lets locate the place that you need to connect.
:
:
:Since I am now at a site that leaves me naked of my schematic / drawing facilities, let me have you find the
: very noticable pair of .05 caps that are just lower left of the pilot lamp on the schema.
:
:
:We are interrested in the junction of the bottom .05 and the 100K above it and the AVC buss wiring which
:then flows over to the left to feed those RF tubes grid that I mentioned.
:
:
:Now in the interim you have four potential problem childs in the respect of those two .05 caps leaking to ground and bleeeeeding down your hard earned AVC voltage . . . . along with two other dudes off to the left that are tied in to the two 100k resistors off from this buss that feed into the mixer stage where you see another .05 to ground being used there and over to the left at the RF stage it looks to be a .047 to ground being used there.
:
: So four filtering caps are being involved.
:Tolerate ZERO leakage from those components.
:
:
:Now for the test . . . . connect the bias supply output resistor to the AVC buss at the very first junction that
:I had initially mentioned .
:
:
:Have the pot setting for putting out max negative voltage and observe the metering and give us that reading as its being proportional of a full scale reading.
:
:
:Reverse the bias supply leads and introduce POSITIVE voltage to the AVC buss for just long enough time to establish a reading and give us the percentage of full scale.
:
:
:
:Standing by . . . . . for test data to see direction of approach for further analysis.
:
:
:
:
:
:
:73's de Edd
:
:
:
:
:
:
:
:
:
:
:
:
:
:::Norm, the tubes tested on 533A. I can test them again. No 24A in place of 35. Tho I had thought about trying one. So thanks for the warning. The strongest station around here is 820 and it is very close. It does cause the most meter deflection but less than 1/8 inch movement. No problem with reading the resistor value as all old dogbone type were clearly marked.
:::Bill
:::
:
:
:
:
::::Hi
::::
:::: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
::::
:::: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
::::
:::: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
::::
::::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
::::
::::Norm
:
:
:
:
:
:
::::
::::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
::::::::Bill
::::::::
:::::::
:::::::
:::::::
:
:
:
:
:
:::::::
:::::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::::::Lewis
:::::::
::::::
:
:
:
:
::::::Thanks Lewis,
::::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::::::Bill
::::::
:::::
:::::
:
:
:
:
:
:::::
:::::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:::::Lewis
:::::
::::
:::
::
:
Wierdly enough . . . . but the last graduation I attended was at high noon on a Saturday. BUT if you merely physically invert the meter 180 degrees, such as they have done, that will result in a normal positioning of that pointer as now being PERCIEVED as being located in the LOWER quadrant of the now reversed / transitioned meter scale. Now, not being able to confirm by the schematic designators nor the parts list in their showing any ganging of capacitors. Are there any more than two sections to your main tuning condenser ? |
:Hi Edd,
:I'm back a little early so I worked up the meter deflections. I didn't mention it but the meter pointer in the off position is on the right side of meter. When set is turned on it assumes the position in the first picture. The second picture is with negative voltage, and the third is positive voltage. Thanks very much for your help.
:Bill
:
:
:
:
:
:
:
:
::
::
::
::
::
::
::
::
::
::
::
::
::
::Sir Bill. . . . . .from VA
::
::
::That sets metering is dependent upon the current consumption of the 1st two RF tubes, the B+ supply level and the grid biasing being supplied to them via the developed AVC.
::
::
::And I am blind on the scale length of the metering scale of the unit, so lets just hereafter be referring as a percentage of meter full scale deflection.
::
::
::Now the B+ coming in to the low side of the metring seems to be a fixed factor and is coming in at quite a hefty level, in the respect of not having incorporating any high value series dropping resistor(s).
::
::
::Not exactly sure on the magnetic field retentivity of old metering , with it not having been specifically designed for more critical intrumentation uses.
::
::
::Now that meters in circuit tuning action range, we . . . CAN . . .evaluate.
::
::
::To initially establish that , refer to my post of:
::
::
::http://www.nostalgiaair.org/Forums/Messages/390/M0086390.htm
::
::
::Which is a stand alone troubleshooting sequence relevant to tuning eye problems and you merely have an electro-mechanical variant here with the RF tubes plate current consumption being the indicator of metering.
::
::
::Refer to the end schematic and the [Pale Yellow] inset of the building up of a test bias supply.
::
::
::Build up that same circuitry and then lets locate the place that you need to connect.
::
::
::Since I am now at a site that leaves me naked of my schematic / drawing facilities, let me have you find the
:: very noticable pair of .05 caps that are just lower left of the pilot lamp on the schema.
::
::
::We are interrested in the junction of the bottom .05 and the 100K above it and the AVC buss wiring which
::then flows over to the left to feed those RF tubes grid that I mentioned.
::
::
::Now in the interim you have four potential problem childs in the respect of those two .05 caps leaking to ground and bleeeeeding down your hard earned AVC voltage . . . . along with two other dudes off to the left that are tied in to the two 100k resistors off from this buss that feed into the mixer stage where you see another .05 to ground being used there and over to the left at the RF stage it looks to be a .047 to ground being used there.
::
:: So four filtering caps are being involved.
::Tolerate ZERO leakage from those components.
::
::
::Now for the test . . . . connect the bias supply output resistor to the AVC buss at the very first junction that
::I had initially mentioned .
::
::
::Have the pot setting for putting out max negative voltage and observe the metering and give us that reading as its being proportional of a full scale reading.
::
::
::Reverse the bias supply leads and introduce POSITIVE voltage to the AVC buss for just long enough time to establish a reading and give us the percentage of full scale.
::
::
::
::Standing by . . . . . for test data to see direction of approach for further analysis.
::
::
::
::
::
::
::73's de Edd
::
::
::
::
::
::
::
::
::
::
::
::
::
::::Norm, the tubes tested on 533A. I can test them again. No 24A in place of 35. Tho I had thought about trying one. So thanks for the warning. The strongest station around here is 820 and it is very close. It does cause the most meter deflection but less than 1/8 inch movement. No problem with reading the resistor value as all old dogbone type were clearly marked.
::::Bill
::::
::
::
::
::
:::::Hi
:::::
::::: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
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::::: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
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::::: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
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:::::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
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:::::Norm
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:::::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
:::::::::Bill
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::::::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
::::::::Lewis
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:::::::Thanks Lewis,
:::::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
:::::::Bill
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::::::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
::::::Lewis
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: : : : : Well Edd, leave it to me to cross the wires. Should read: The second picture is with positive voltage, and the third is negative voltage. All the resistors from the DET/AVC tube's plate are new and in tolerance and wired as the schematic indicates. The wee bit of B+ (12.72)from just above 340 ohm (lug 3) goes to the 100K and then to a 250K. The old 250k measured 555K and was replaced with new one measuring 254K. The 250K goes to the DET grid. All of the old resistors were replaced. I just think it's too much of a gamble even if in 10% tolerance. The tuning cap is four gang. And I see only one tuning adjustment for the IF's. But isn't the tri-resonator just "tuned" to pass on? The meter does not have a resistor across the terminals and I'm going to look at that zero screw again. I believe it's a fake. With the set right on 820 the plate voltage measured a negative 3.566 and tuned off it was negative .696 volts. Oh, and it's Virginia. Not from VA but I've been here going on 31 years. Bill
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::Hi Edd,
::I'm back a little early so I worked up the meter deflections. I didn't mention it but the meter pointer in the off position is on the right side of meter. When set is turned on it assumes the position in the first picture. The second picture is with negative voltage, and the third is positive voltage. Thanks very much for your help.
::Bill
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::: ::: ::: ::: ::: ::: ::: ::: ::: ::: :::Sir Bill. . . . . .from VA ::: ::: :::That sets metering is dependent upon the current consumption of the 1st two RF tubes, the B+ supply level and the grid biasing being supplied to them via the developed AVC. ::: ::: :::And I am blind on the scale length of the metering scale of the unit, so lets just hereafter be referring as a percentage of meter full scale deflection. ::: ::: :::Now the B+ coming in to the low side of the metring seems to be a fixed factor and is coming in at quite a hefty level, in the respect of not having incorporating any high value series dropping resistor(s). ::: ::: :::Not exactly sure on the magnetic field retentivity of old metering , with it not having been specifically designed for more critical intrumentation uses. ::: ::: :::Now that meters in circuit tuning action range, we . . . CAN . . .evaluate. ::: ::: :::To initially establish that , refer to my post of: ::: ::: :::http://www.nostalgiaair.org/Forums/Messages/390/M0086390.htm ::: ::: :::Which is a stand alone troubleshooting sequence relevant to tuning eye problems and you merely have an electro-mechanical variant here with the RF tubes plate current consumption being the indicator of metering. ::: ::: :::Refer to the end schematic and the [Pale Yellow] inset of the building up of a test bias supply. ::: ::: :::Build up that same circuitry and then lets locate the place that you need to connect. ::: ::: :::Since I am now at a site that leaves me naked of my schematic / drawing facilities, let me have you find the ::: very noticable pair of .05 caps that are just lower left of the pilot lamp on the schema. ::: ::: :::We are interrested in the junction of the bottom .05 and the 100K above it and the AVC buss wiring which :::then flows over to the left to feed those RF tubes grid that I mentioned. ::: ::: :::Now in the interim you have four potential problem childs in the respect of those two .05 caps leaking to ground and bleeeeeding down your hard earned AVC voltage . . . . along with two other dudes off to the left that are tied in to the two 100k resistors off from this buss that feed into the mixer stage where you see another .05 to ground being used there and over to the left at the RF stage it looks to be a .047 to ground being used there. ::: ::: So four filtering caps are being involved. :::Tolerate ZERO leakage from those components. ::: ::: :::Now for the test . . . . connect the bias supply output resistor to the AVC buss at the very first junction that :::I had initially mentioned . ::: ::: :::Have the pot setting for putting out max negative voltage and observe the metering and give us that reading as its being proportional of a full scale reading. ::: ::: :::Reverse the bias supply leads and introduce POSITIVE voltage to the AVC buss for just long enough time to establish a reading and give us the percentage of full scale. ::: ::: ::: :::Standing by . . . . . for test data to see direction of approach for further analysis. ::: ::: ::: ::: ::: ::: :::73's de Edd ::: ::: ::: ::: |
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:::::Norm, the tubes tested on 533A. I can test them again. No 24A in place of 35. Tho I had thought about trying one. So thanks for the warning. The strongest station around here is 820 and it is very close. It does cause the most meter deflection but less than 1/8 inch movement. No problem with reading the resistor value as all old dogbone type were clearly marked.
:::::Bill
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::::::Hi
::::::
:::::: Right, AVC goes negative when stronger stations are tuned in. Takes a good antenna, strong station and alignment to get the most meter movement.
::::::
:::::: In this radio the meter moves by reduction of plate current in the RF and Mixer stages. Are proper, good tubes in these stages? Sometimes 24A and 35 are interchanged. Either may work for sound but not meter operation.
::::::
:::::: The schematic shows resistors as .5 ohms etc. This is an error. Resistors marked like that should be shown as meg.
::::::
::::::http://www.nostalgiaair.org/PagesByModel/436/M0021436.pdf
::::::
::::::Norm
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::::::::::I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
::::::::::Bill
::::::::::
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:::::::::
:::::::::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::::::::Lewis
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::::::::Thanks Lewis,
::::::::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::::::::Bill
::::::::
:::::::
:::::::
:::
:::
:::
:::
:::
:::::::
:::::::I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:::::::Lewis
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:
http://www.radiomuseum.org/forum/history_of_tuning_indicators_meters_graphs_magic_eye_led.html
::::Bill
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:::On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:::Lewis
:::
::
::Thanks Lewis,
::I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
::Bill
::
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:
:
:I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:Lewis
:
Bill
Initially . . . I'm adding on a Stromberger Carlsonator marked up Schema at the end that is assigned RF and IF tuned circuit identifiers in case we need to differentiate in their functions/ assignments in the future. Now if the AVC can not be raised further by any optimizing of the sets alignmant / tuning, seems like your desired meters increasing of tuning spread would be dependent upon shifting the biasing parameters around the detector / AVC circuitry. Standing by for your initial / potential further optimizatoin of tuning. |
Stromberger Carlsonator 29 . . . working . . . SCHEMATIC:  |
I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on. IPAddress: ***.145.88.203 Correct Lewis, more negative.
On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
Lewis
I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
Lewis
Bill
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: : : : : : : : : : :Sir Bill . . . . . . : : : : :Initially . . . I'm adding on a Stromberger Carlsonator marked up Schema at the end that is assigned RF and IF tuned circuit identifiers in case we need to differentiate in their functions/ assignments in the future. : : : : :The tuning cap is four gang. : : : :Right, and am I correctly seeing them as: : : :The assigned [Pink] #2 for the antennna input stage : : :The assigned [Pink] #3 for the RF amp input stage : : :The assigned [Pink] #4 for the Mixer input stage : : :The assigned [Blue] #4 for the antennna input stage : : :(Two assigned #4 sections but I will just further differentiate : : :with the [Blue] being for the oscillator and not redraw.) : : : :And I see only one tuning adjustment for the IF's. : : :But isn't the tri-resonator just "tuned" to pass on? : : : :Yep . .that would be the tuned circuit between its pri and secondary coils. : : :NOW . . . which of those potential GREEN A-B-C-D adjustment trimmers is your found "one" : : :adjustment, and could the others be hidden away a bit, internally of a can ? : : : :The meter does not have a resistor across the terminals and I'm going to look at that zero screw again. I believe it's a fake. : : : :1 . . . : : :Just wanted to be sure that no meter shunting was involved for "fine tuning" meter scaling. : : :2 . . . : : :That's certainly the way that I was seeing it . . . as possibly being a reflected image of some mechanics of your camera coming off the meters glass . . . its lighting angle possibly having been just right for its creation on that one photo, as it was not even seen on the other shot angles of the two other photos. : : : :With the set right on 820 the plate voltage measured a negative 3.566 and tuned off it was negative .696 volts. : : : :Soooooo that 820 stations optimal . . . to date . . .- 3.566 developed AVC voltage is falling quite shy of that -9V that you were testing with. : : :Assuming now that you had all RF---IF adjustments optimally peaked on that 820 station and that you have no :increased resistance on your tuned circuit coils ? : : :I'll clarify that for you . . . et al: : : :Should your coils have been wound with Litz wire . . . with time onset, either a combo of: : : :1 . . . Poor Litz to connector interface soldering.(Factory) : : :2 . . .Excess time and heat that the rosin / wire junction might have been subjected to.(Factory) : : :3 . . .Cross contamination of the irons tip with having been used with acid core on a previous chassis mechanical :. . . . .soldering operation.(Factory) : : :4 . . ."Alligatoring" "checkering" of the wires old generation enamel coating . . . exposing bare copper for erosion.(AGING) : : :5 . . .Our current days typically higher level of airborne (humidity retained) alkaline and acidic contaminants to react with that . . . . .once exposed copper and slowly erode away at it. : : :Now the end result is that 10/44 Litz . . . . that's ten strands of spiraled and interwound 44 gauge wire . .and that it is now found only retaining 3 ? intact strands . . . is in no way going to exhibit the tuned "Q" and performance of that coils original resonant winding. : : :My fix . . . when finding this . . . is to razor blade flush cut at the connector to get as much of that finite wire length in order to then magnify/examine that bad end and re tin ALL of its leads and then fabricate an "eye of a needle" with AC zip cord's bare copper wire, supplying but a single strand, and then tin it and then flow solder it onto the coil / lug connector/ terminal. : : :Then the tinned Litz end is inserted into the central open "eye of the needle" and rapid re-flow soldered. : : : : : :Now if the AVC can not be raised further by any optimizing of the sets alignmant / tuning, seems like your desired meters increasing of tuning spread would be dependent upon shifting the biasing parameters around the detector / AVC circuitry. : : :To wit: : : :The detector circuitry is working with the 1st grid and the cathode of the Demod/AVC tube and their feed into the 250K and 100K divider resistors that are then routed down to their counterpoise biasing source being acquired down at the 340 ohm / 3080 ohm junction down within the power supply. : : :It will take some shifting of those resistors interelational ratios to accomplish scale tailoring to your end need. : : : :Standing by for your initial / potential further optimizatoin of tuning. : : : : : :73's de Edd Sir Edd, : |
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: : : :Stromberger Carlsonator 29 . . . working . . . SCHEMATIC: : : : : : : : : : : |
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:I have the radio playing loud and clear, getting every watt out of the 45's. The pointer takes up position about 1/4 from left. It barely moves when tuning a station. How do I get more "swing to the right" from it? Otherwise more visual tho it does peak when right on.
:Bill
:
:
:
:
:
:On that receiver, the AVC controls the gain of the RF and converter sections by driving those tubes toward cutoff, which lowers the current they draw, so we have two possibilities here, the AVC or one (or both) of the front end tubes. A third possibility is the meter itself, but not very likely. I don't know what the AVC should go down to (negative Voltage, y'know) but I woruld suspect that firsst, then the tubes.
:Lewis
:
:
:Thanks Lewis,
:I have checked the tubes over and over and they are fine, life test ok. I measure about 1 and third negative volts. I do think it should be higher. I used new caps but now I'm thinking about lowering the value of caps involved in the AVC and see what happens. The schematic is hard to read and based on what I measured the old ones and a guess I could be off. I did look at the other similiar Stromberg schematics. I do know the set plays loud and clear. The meter reads about 850 ohms if I recall right.
:Bill
:
:
:
:
:I am not sure about that AVC Voltage, seems to me it should be lower (more negative) if you have a fairly strong station. Help, anyone?
:Lewis
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:
:Correct Lewis, more negative.
:Bill
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