HEYY... I once owned one of THOSE...way back at their day one. If still intact, you certainly noticed that loooooong coiled up hank of antenna wire
( An off brown color and double cotton covered, very flexible, stranded wire ....no less) that is / was hanging out the rear of the unit and connected onto the
antenna coil mounted just above the tuning condenser. That wire was definitely there for a reason.


I had saved up my few coins to buy a cheap radio, and that was what I got was one cheeeep radio !

Lastly.... you have tuned the radio to the specs given haven't you, as there is only the RF section trimmer cap, the osc padder cap and the two sections of the single IF transformer. If correct / optimized, you should be able to try the radio at the Low end of the AM band (~600kc)........ and then Mid band (of its tuning condensers travel /position which is typically~950kc) and then lastly at the high end of the dial( ~1400-1600) on receiving stations in those spectrum's.


In doing that tuning you would have the antenna wire all strung out. Then as a final evaluation, try the three positions, but this time grasp the larger coil of the antenna transformer and see if reception improves on any stations. If so, more work on the overall alignment / tracking is in order.
[Or adding another tube socket and wiring in an IF amp tube and its output transformer......with what ?....a mere 4 or 5 parts..... then you would have an AA-5 ! considering that real estate just to the rear of the tuning condenser might just accommodate a 7 pin mini tube socket, a 12BA6 IF tube, a miniature 3/4 inch sized I.F. transformer, which would then become the units 1st IF transformer]


One other final thought, in case your described reception was REALLY dismal, or that you are sited in the middle of the Mojave desert.

Drop a low loading type of instrumentation like a VTVM or more likely these days, a DVM across the R2 grid resistor and take a reading for an expected negative voltage being across it . It will be different values for the low end of the dial as compared to the other end, by virtue of osc action tapering off. This was to confirm a working local oscillator, as you actually might be at the other end of the reception with a strong station punching through, even though the osc is not working.
However, expect the station tuning into to be broad and not sharp in that situation.

73's de Edd

:I have recapped and restored this little Sears Model 1 and aligned it to specs, but it will not receive stations at any point on the band. I went back through it and checked the tubes,caps and resistor values and everything looks good. If I connect the antenna hank to an external antenna, I can barely hear one station around 1100. This radio has only one IF stage, which I peaked, and then peaked the antenna at 1400 as instructed. Sounds like something really obvious that I'm overlooking on this simple design. Any help is greatly appreciated!

:
:
:
:
:
:
:
:HEYY... I once owned one of THOSE...way back at their day one. If still intact, you certainly noticed that loooooong coiled up hank of antenna wire
:( An off brown color and double cotton covered, very flexible, stranded wire ....no less) that is / was hanging out the rear of the unit and connected onto the
:antenna coil mounted just above the tuning condenser. That wire was definitely there for a reason.
:
:
:I had saved up my few coins to buy a cheap radio, and that was what I got was one cheeeep radio !
:
:Lastly.... you have tuned the radio to the specs given haven't you, as there is only the RF section trimmer cap, the osc padder cap and the two sections of the single IF transformer. If correct / optimized, you should be able to try the radio at the Low end of the AM band (~600kc)........ and then Mid band (of its tuning condensers travel /position which is typically~950kc) and then lastly at the high end of the dial( ~1400-1600) on receiving stations in those spectrum's.
:
:
:In doing that tuning you would have the antenna wire all strung out. Then as a final evaluation, try the three positions, but this time grasp the larger coil of the antenna transformer and see if reception improves on any stations. If so, more work on the overall alignment / tracking is in order.
:[Or adding another tube socket and wiring in an IF amp tube and its output transformer......with what ?....a mere 4 or 5 parts..... then you would have an AA-5 ! considering that real estate just to the rear of the tuning condenser might just accommodate a 7 pin mini tube socket, a 12BA6 IF tube, a miniature 3/4 inch sized I.F. transformer, which would then become the units 1st IF transformer]
:
:
:One other final thought, in case your described reception was REALLY dismal, or that you are sited in the middle of the Mojave desert.
:
:Drop a low loading type of instrumentation like a VTVM or more likely these days, a DVM across the R2 grid resistor and take a reading for an expected negative voltage being across it . It will be different values for the low end of the dial as compared to the other end, by virtue of osc action tapering off. This was to confirm a working local oscillator, as you actually might be at the other end of the reception with a strong station punching through, even though the osc is not working.
: However, expect the station tuning into to be broad and not sharp in that situation.
:
:
:
:
:
:
:73's de Edd
:
:
:
:
::I have recapped and restored this little Sears Model 1 and aligned it to specs, but it will not receive stations at any point on the band. I went back through it and checked the tubes,caps and resistor values and everything looks good. If I connect the antenna hank to an external antenna, I can barely hear one station around 1100. This radio has only one IF stage, which I peaked, and then peaked the antenna at 1400 as instructed. Sounds like something really obvious that I'm overlooking on this simple design. Any help is greatly appreciated!

OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
:
:OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

:Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
:
:::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
::
::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

Leting YOU provide its images....compliments of your attic.....hi..hi



Soooo.... does this mean that this might be your second / another model #1 or are you just now, trying to get the same unit up to speed electrical and performance wise

And ...with that healthy oscillator presence confirmed, if that were my unit to troubleshoot, I would be now wanting to look at the main resonant winding of the antenna coil / transformer more closly.

When you tune into the one received station, does it seem to exhibit a bit wider tuning action than normal, or is it quite sharp..as is normal?

With the age / shrinkage of the wax on that antenna transformer topside, can you confirm continuity, and normal coil resistance of the main resonant winding of that t-former. The answer about its primary portion would have been answered if you had enacted the grasping aspect mentioned.

If the problem was not there, I would then be moving on to the sole IF transformer and testing its windings...and if they checked out...I would be lifting half of its connections..to wit its plate connection and the grid connection wires, and subbing in any other / available / borrowed 455 transformer, using 4 short leads to solder tack it into circuit.

I would expect your unit to be bringing in upwards of a dozen stations in the daytime, unless you live in Podunk Holler, my old unit routinely picked up small Texas 1Kw daytime stations of the surrounds and a 5Kw at 120 miles....and then,no problemo at all... at nightime..when all came rolling in!.

ZUJ' ing

73's de Edd

: It is -5v to -5.5v depending on dial setting, with max occurring in center of band. Also, the voltage changes to pos when meter leads are reversed (which makes sense to me, does it to you?)
:Thanks-
:Stan
::
::
::How about the voltage level read across the mixer-local oscillator's R2 grid resistor ?
::
::73's de Edd
::
::
::
:::Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
:::
:::::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
::::
::::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

The customer is interested in it for her husband, who had one as a young boy. I'd sure like to make his day!
Stan
:
:
:
:Leting YOU provide its images....compliments of your attic.....hi..hi
:
:
:
:Soooo.... does this mean that this might be your second / another model #1 or are you just now, trying to get the same unit up to speed electrical and performance wise
:
:And ...with that healthy oscillator presence confirmed, if that were my unit to troubleshoot, I would be now wanting to look at the main resonant winding of the antenna coil / transformer more closly.
:
:When you tune into the one received station, does it seem to exhibit a bit wider tuning action than normal, or is it quite sharp..as is normal?
:
:With the age / shrinkage of the wax on that antenna transformer topside, can you confirm continuity, and normal coil resistance of the main resonant winding of that t-former. The answer about its primary portion would have been answered if you had enacted the grasping aspect mentioned.
:
:If the problem was not there, I would then be moving on to the sole IF transformer and testing its windings...and if they checked out...I would be lifting half of its connections..to wit its plate connection and the grid connection wires, and subbing in any other / available / borrowed 455 transformer, using 4 short leads to solder tack it into circuit.
:
:I would expect your unit to be bringing in upwards of a dozen stations in the daytime, unless you live in Podunk Holler, my old unit routinely picked up small Texas 1Kw daytime stations of the surrounds and a 5Kw at 120 miles....and then,no problemo at all... at nightime..when all came rolling in!.
:
:
:
:ZUJ' ing
:
:
:
:
:
:73's de Edd
:
:
:
:
:
:: It is -5v to -5.5v depending on dial setting, with max occurring in center of band. Also, the voltage changes to pos when meter leads are reversed (which makes sense to me, does it to you?)
::Thanks-
::Stan
:::
:::
:::How about the voltage level read across the mixer-local oscillator's R2 grid resistor ?
:::
:::73's de Edd
:::
:::
:::
::::Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
::::
::::::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
:::::
:::::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

:The radio has been in my collection unused for a year and a half since I originally restored it. I had gotten it to perform well before. So now someone is interested in purchasing it and it is not receiving as it did. Continuity of coils (antenna and T1) tests fine. Reception is up to two stations using an extension to the hank (total of 18-20 feet). Reception also improves when I actually touch the connection of the antenna coil which runs to stator of C1, but still not as it was/should be. I have reheated all the solder joints on the antenna coil and C1/C2 in case one may have been cold.
:Of course I will not sell it as a restored radio unless/until it works as it should. You description of that helps set my expectations...ie it should work just like any other 4-tuber.
:
:The customer is interested in it for her husband, who had one as a young boy. I'd sure like to make his day!
:Stan
::
::
::
::Leting YOU provide its images....compliments of your attic.....hi..hi
::
::
::
::Soooo.... does this mean that this might be your second / another model #1 or are you just now, trying to get the same unit up to speed electrical and performance wise
::
::And ...with that healthy oscillator presence confirmed, if that were my unit to troubleshoot, I would be now wanting to look at the main resonant winding of the antenna coil / transformer more closly.
::
::When you tune into the one received station, does it seem to exhibit a bit wider tuning action than normal, or is it quite sharp..as is normal?
::
::With the age / shrinkage of the wax on that antenna transformer topside, can you confirm continuity, and normal coil resistance of the main resonant winding of that t-former. The answer about its primary portion would have been answered if you had enacted the grasping aspect mentioned.
::
::If the problem was not there, I would then be moving on to the sole IF transformer and testing its windings...and if they checked out...I would be lifting half of its connections..to wit its plate connection and the grid connection wires, and subbing in any other / available / borrowed 455 transformer, using 4 short leads to solder tack it into circuit.
::
::I would expect your unit to be bringing in upwards of a dozen stations in the daytime, unless you live in Podunk Holler, my old unit routinely picked up small Texas 1Kw daytime stations of the surrounds and a 5Kw at 120 miles....and then,no problemo at all... at nightime..when all came rolling in!.
::
::
::
::ZUJ' ing
::
::
::
::
::
::73's de Edd
::
::
::
::
::
::: It is -5v to -5.5v depending on dial setting, with max occurring in center of band. Also, the voltage changes to pos when meter leads are reversed (which makes sense to me, does it to you?)
:::Thanks-
:::Stan
::::
::::
::::How about the voltage level read across the mixer-local oscillator's R2 grid resistor ?
::::
::::73's de Edd
::::
::::
::::
:::::Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
:::::
:::::::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
::::::
::::::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

One suggestion I was thinking about making was to check the high value resistors in the audio circuit. Some are very high to begin with, and if they drift any higher, they'll leave the audio circuitry in a very unstable condition.

One thing you can do to possibly increase gain is to change the 12sQ7 plate resistor from 470K to 1 Meg, though it might not make a difference other than with bass response.

The Philco 80 uses regeneration in the IF stage, which might greatly improve your radio. However, that requires winding extra windings on the IF transformer, as well as changing the 12SQ7 to a 12SG7. Though I have had fair luck with fidelity when using regenerative detectors, there still lies the possibility for the detector to perform as a square law detector at low volumes, which puts a lot of distortion in the audio. Placing the volume control after the detector, however, with an automatic volume control circuit maintaining high signal levels to the detector, can remedy this.

One nice thing about a regenerative detector in the IF stage is that the IF stage never changes in frequency, and so you don't have to worry about adjusting the regeneration control. The regeneration control simply lingers under the chassis for the occasional touch-up.

Thomas

T.

OK then, in giving the benefit of the doubt of the unit having a good mixer tube, and your having bounced the naked chassis flat upon the wood bench a few times checking for any loose connections / bad solder joints, as well as a probing of the RF section with a wooden dowel for same. The confirmation of the 90-100VDC power being up to that value and present at the plate and screen of the mixer. Your have already acsertained the presence and healthy level of the oscillator signal.PLUS you have many other receivers to have placed another full AA5 in the same operating spot and the same outlet and have ascertained the expected number of stronger stations to be coming in across the BCB at your locale.

PLUS your having used a signal generator and ran the spectrum on its AM input, osc freq, the sets overall tracking and I.F. alignment, BUT and heavy on the BUT, with your assuredly having swamped the RF-I.F. section a bit with the RF signal generator signal, with your having been able to receive all of those different frequencies. You would expect that the receiver would NOW be receiving off the air signals accordingly. In that case you were apparently driving in millivolt RF level testing levels, whereas you are now trying for microvolt levels in off the air reception of signals. The differentiation is somewhat difficult, unless you were using a lab quality Sig Gen and a shielded decade attenuator following its output to assure the exact RF inputting level. With your just receiving one off the air signal..... weakly,at that...should now attest to the higher input levels that were needed for working with during your alignment procedure.


With your info on the sole station received...but not yet confirmed to me as the sharpness of tuning....the initial RF front end is the main area of suspect, as any suggested fault in the latter audio circuitry should STILL let the weaker stations be heard....even though feebly.


Wonder if you might now might take metering in hand as you did back at the osc stage and have the ground lead (red lead) to the same common ground ...not chassis gnd.....as it was done on the osc reading, as a negative voltage is to be expected here also, and the other meter lead connection is to be made at the AVC line of the receiver. There are two levels, the lowest as is connected to the frame of the tuning cap and the hihest level right out of the bottom leg of the secondary of the i.F. transformers secondary where it is to then be dropped by the 4.7 meg resistor below it. Initially do the metering connection at the tuning condensers frame and tune in to your sole station and see how much of a voltage swing occurs as you peak onto the tuning of the station. Then probe over to the high level point mentioned and settle upon the second possibility, if the first level was very weak.
If you are not getting quite a bit of a swing in level when tuning into the station and then off the station, the very frontal RF input stage is suspect.

As the next test, tune in "the" station and take a jumper wire and connect the frame of the tuning condenser to the familiar common ground, that being to temporarily disable the AVC feedback loop and see if the volume comes up or any other stations will now come in.


If no improvements by now I think that you need to solder tack together ...or fully build in time... the special AF-RF combined probe.... that I made and frequently use in the RF sectors. It has voltage doubling in the RF mode...no less !, plus it can equally be used in the tracing of audio signals in the last stages of the set. My schematc of how I built it is shown below.

This all being in consideration, that you do not have A signal tracer, since you would have the RF problem figured out long with its use.

It is intended to have its RCA jack plugged into an audio amplifier.....WITH..AC line isolated power supply, thus, no shock hazards or more technically important...ground loop induced hummmmms, to drown out / interfere in the produced audio to be listened to.

The IDEAL amplifier being a computer external speakers package ( For only $3-5 used... fron a thrift store, etc )with its own amp electronics and its own dedicated volume control, with the isolation aspect being provided by either / both batteries, or its small wall wart transformer.

For the probes shielded line I like to use one of the flexible larger patch ( lower inherent cap..less RF attenuation ) cables (Yellow coded) for the video line of a Video + Audio R&L channels of a TV/VCR/VIDEO patch cable.

If you take that probes ground lead clip to isolated chassis ground and use the probe tip right to the tuning condensers RF stator plates /ant coil junction and crank up the audio, you should start receiving all of the stronger stations as the tuning condenser is swung thru full range. If not, you can fault one of those components right there. And I really think that is your trouble area, but IF some stations are coming in a bit, you can then move up to the plate of the mixer, where the frequency will then still be selective when tuning, but volume should come up appreciably . The last probe test area would be the top side of the secondary of the I.F. transformer.

Some where in this loop, you should have pinpointed where the signal loss was....or never did build up from.


Standing by for feedback....

73's de Edd

::Progress! I backed the oscillator adjustment screw out past its normal travel to be sure the plastic insulator was ok, and then turned it back in. On the way back in, I picked up a stronger signal, so evidently I was tuned to a harmonic as the other gentlemen suggested. Perhaps a full quarter turn out from the previous adjustment is where it is now. I'm on the right track. How very obvious! Sometimes this hobby makes me feel pretty dumb. But at least I'm persistent.
:
::The radio has been in my collection unused for a year and a half since I originally restored it. I had gotten it to perform well before. So now someone is interested in purchasing it and it is not receiving as it did. Continuity of coils (antenna and T1) tests fine. Reception is up to two stations using an extension to the hank (total of 18-20 feet). Reception also improves when I actually touch the connection of the antenna coil which runs to stator of C1, but still not as it was/should be. I have reheated all the solder joints on the antenna coil and C1/C2 in case one may have been cold.
::Of course I will not sell it as a restored radio unless/until it works as it should. You description of that helps set my expectations...ie it should work just like any other 4-tuber.
::
::The customer is interested in it for her husband, who had one as a young boy. I'd sure like to make his day!
::Stan
:::
:::
:::

:::
:::Soooo.... does this mean that this might be your second / another model #1 or are you just now, trying to get the same unit up to speed electrical and performance wise
:::
:::And ...with that healthy oscillator presence confirmed, if that were my unit to troubleshoot, I would be now wanting to look at the main resonant winding of the antenna coil / transformer more closly.
:::
:::When you tune into the one received station, does it seem to exhibit a bit wider tuning action than normal, or is it quite sharp..as is normal?
:::
:::With the age / shrinkage of the wax on that antenna transformer topside, can you confirm continuity, and normal coil resistance of the main resonant winding of that t-former. The answer about its primary portion would have been answered if you had enacted the grasping aspect mentioned.
:::
:::If the problem was not there, I would then be moving on to the sole IF transformer and testing its windings...and if they checked out...I would be lifting half of its connections..to wit its plate connection and the grid connection wires, and subbing in any other / available / borrowed 455 transformer, using 4 short leads to solder tack it into circuit.
:::
:::I would expect your unit to be bringing in upwards of a dozen stations in the daytime, unless you live in Podunk Holler, my old unit routinely picked up small Texas 1Kw daytime stations of the surrounds and a 5Kw at 120 miles....and then,no problemo at all... at nightime..when all came rolling in!.
:::
:::
:::
:::ZUJ' ing
:::
:::
:::
:::
:::
:::73's de Edd
:::
:::
:::
:::
:::
:::: It is -5v to -5.5v depending on dial setting, with max occurring in center of band. Also, the voltage changes to pos when meter leads are reversed (which makes sense to me, does it to you?)
::::Thanks-
::::Stan
:::::
:::::
:::::How about the voltage level read across the mixer-local oscillator's R2 grid resistor ?
:::::
:::::73's de Edd
:::::
:::::
:::::
::::::Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
::::::
::::::::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
:::::::
:::::::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.

Stan
:
:Also caught the bit on the osc padder but only suspicion it to possibly have gotten a bit closer on optimal tracking, but far from optimal if more stations are not rolling in.
:
:
:
:
:
:
:
:OK then, in giving the benefit of the doubt of the unit having a good mixer tube, and your having bounced the naked chassis flat upon the wood bench a few times checking for any loose connections / bad solder joints, as well as a probing of the RF section with a wooden dowel for same. The confirmation of the 90-100VDC power being up to that value and present at the plate and screen of the mixer. Your have already acsertained the presence and healthy level of the oscillator signal.PLUS you have many other receivers to have placed another full AA5 in the same operating spot and the same outlet and have ascertained the expected number of stronger stations to be coming in across the BCB at your locale.
:
:PLUS your having used a signal generator and ran the spectrum on its AM input, osc freq, the sets overall tracking and I.F. alignment, BUT and heavy on the BUT, with your assuredly having swamped the RF-I.F. section a bit with the RF signal generator signal, with your having been able to receive all of those different frequencies. You would expect that the receiver would NOW be receiving off the air signals accordingly. In that case you were apparently driving in millivolt RF level testing levels, whereas you are now trying for microvolt levels in off the air reception of signals. The differentiation is somewhat difficult, unless you were using a lab quality Sig Gen and a shielded decade attenuator following its output to assure the exact RF inputting level. With your just receiving one off the air signal..... weakly,at that...should now attest to the higher input levels that were needed for working with during your alignment procedure.
:
:
:With your info on the sole station received...but not yet confirmed to me as the sharpness of tuning....the initial RF front end is the main area of suspect, as any suggested fault in the latter audio circuitry should STILL let the weaker stations be heard....even though feebly.
:
:
:Wonder if you might now might take metering in hand as you did back at the osc stage and have the ground lead (red lead) to the same common ground ...not chassis gnd.....as it was done on the osc reading, as a negative voltage is to be expected here also, and the other meter lead connection is to be made at the AVC line of the receiver. There are two levels, the lowest as is connected to the frame of the tuning cap and the hihest level right out of the bottom leg of the secondary of the i.F. transformers secondary where it is to then be dropped by the 4.7 meg resistor below it. Initially do the metering connection at the tuning condensers frame and tune in to your sole station and see how much of a voltage swing occurs as you peak onto the tuning of the station. Then probe over to the high level point mentioned and settle upon the second possibility, if the first level was very weak.
:If you are not getting quite a bit of a swing in level when tuning into the station and then off the station, the very frontal RF input stage is suspect.
:
:As the next test, tune in "the" station and take a jumper wire and connect the frame of the tuning condenser to the familiar common ground, that being to temporarily disable the AVC feedback loop and see if the volume comes up or any other stations will now come in.
:
:
:If no improvements by now I think that you need to solder tack together ...or fully build in time... the special AF-RF combined probe.... that I made and frequently use in the RF sectors. It has voltage doubling in the RF mode...no less !, plus it can equally be used in the tracing of audio signals in the last stages of the set. My schematc of how I built it is shown below.
:
:This all being in consideration, that you do not have A signal tracer, since you would have the RF problem figured out long with its use.
:
:It is intended to have its RCA jack plugged into an audio amplifier.....WITH..AC line isolated power supply, thus, no shock hazards or more technically important...ground loop induced hummmmms, to drown out / interfere in the produced audio to be listened to.
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:The IDEAL amplifier being a computer external speakers package ( For only $3-5 used... fron a thrift store, etc )with its own amp electronics and its own dedicated volume control, with the isolation aspect being provided by either / both batteries, or its small wall wart transformer.
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:For the probes shielded line I like to use one of the flexible larger patch ( lower inherent cap..less RF attenuation ) cables (Yellow coded) for the video line of a Video + Audio R&L channels of a TV/VCR/VIDEO patch cable.
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:If you take that probes ground lead clip to isolated chassis ground and use the probe tip right to the tuning condensers RF stator plates /ant coil junction and crank up the audio, you should start receiving all of the stronger stations as the tuning condenser is swung thru full range. If not, you can fault one of those components right there. And I really think that is your trouble area, but IF some stations are coming in a bit, you can then move up to the plate of the mixer, where the frequency will then still be selective when tuning, but volume should come up appreciably . The last probe test area would be the top side of the secondary of the I.F. transformer.
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:Some where in this loop, you should have pinpointed where the signal loss was....or never did build up from.
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:Standing by for feedback....
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:73's de Edd
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:::Progress! I backed the oscillator adjustment screw out past its normal travel to be sure the plastic insulator was ok, and then turned it back in. On the way back in, I picked up a stronger signal, so evidently I was tuned to a harmonic as the other gentlemen suggested. Perhaps a full quarter turn out from the previous adjustment is where it is now. I'm on the right track. How very obvious! Sometimes this hobby makes me feel pretty dumb. But at least I'm persistent.
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:::The radio has been in my collection unused for a year and a half since I originally restored it. I had gotten it to perform well before. So now someone is interested in purchasing it and it is not receiving as it did. Continuity of coils (antenna and T1) tests fine. Reception is up to two stations using an extension to the hank (total of 18-20 feet). Reception also improves when I actually touch the connection of the antenna coil which runs to stator of C1, but still not as it was/should be. I have reheated all the solder joints on the antenna coil and C1/C2 in case one may have been cold.
:::Of course I will not sell it as a restored radio unless/until it works as it should. You description of that helps set my expectations...ie it should work just like any other 4-tuber.
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:::The customer is interested in it for her husband, who had one as a young boy. I'd sure like to make his day!
:::Stan
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::::Soooo.... does this mean that this might be your second / another model #1 or are you just now, trying to get the same unit up to speed electrical and performance wise
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::::And ...with that healthy oscillator presence confirmed, if that were my unit to troubleshoot, I would be now wanting to look at the main resonant winding of the antenna coil / transformer more closly.
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::::When you tune into the one received station, does it seem to exhibit a bit wider tuning action than normal, or is it quite sharp..as is normal?
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::::With the age / shrinkage of the wax on that antenna transformer topside, can you confirm continuity, and normal coil resistance of the main resonant winding of that t-former. The answer about its primary portion would have been answered if you had enacted the grasping aspect mentioned.
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::::If the problem was not there, I would then be moving on to the sole IF transformer and testing its windings...and if they checked out...I would be lifting half of its connections..to wit its plate connection and the grid connection wires, and subbing in any other / available / borrowed 455 transformer, using 4 short leads to solder tack it into circuit.
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::::I would expect your unit to be bringing in upwards of a dozen stations in the daytime, unless you live in Podunk Holler, my old unit routinely picked up small Texas 1Kw daytime stations of the surrounds and a 5Kw at 120 miles....and then,no problemo at all... at nightime..when all came rolling in!.
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::::ZUJ' ing
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::::73's de Edd
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::::: It is -5v to -5.5v depending on dial setting, with max occurring in center of band. Also, the voltage changes to pos when meter leads are reversed (which makes sense to me, does it to you?)
:::::Thanks-
:::::Stan
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::::::How about the voltage level read across the mixer-local oscillator's R2 grid resistor ?
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::::::73's de Edd
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:::::::Thanks much for your suggestion. I tried it without success. Reception is so weak it hardly picks up the sig gen signal. Any other thoughts are appreciated!
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:::::::::Let me start by saying nice radio. I really like 4 tube designs for their simplicity. Now, you might try what I did on a Hallicrafters S38D. Start with the radio at 1400 on the dial, and adjust the local oscillator for 1855 Khz (1400 + 455). Then find a station near 1400 so you know that it is correct on the dial (or use an R.F. frequency generator set to the same frequency) and peak the I.F. This should hopefully correct your problem just in case the I.F. is set for an image frequency (or something like that). I hope this helps.
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::::::::OOPS! I also meant to say to use a frequency counter if you have one something like the one Radio Shack used to sell about ten years ago. Just place it near to the radio but not so close as to affect the oscillator. You just want to pick up the L.O. and set it for the position of the dial plus the I.F. since this is how most radios work.