For Edd (or others) - Reply to a Post

1/16/2009 2:33:28 PMJerry

Edd–
The following is your reply to my post together with my return question. If you read this post, I would appreciate your comments.

Thanks,
Jerry

First Reply by Edd:
Capacitor Installation
Posted by Jerry on 01/14/2009 16:18
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I never did tune into that discussion, since I thought it was about some type of capacitor or some like related situation.
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:On that sets DISCRIMINATOR circuit, and after all of the bouncy-bouncy back and forth possibilities, did you eventually get that electrolytic summing capacitor installed in the correct manner. . .which it initially was in. . . . from its factory installation.
: The elects + goes to ground.
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:Refer to the newer # 1065 Silvering-tone model, which wasn't quite so chintzy on parts count and utilized the more common series matched pair of loading resistors to then establish a tap for metering. That then is accomplishing the infinitely easier evaluation of alignment via the use of a VTVM and its zero center viewing capability.
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:That procedure will then let you view the symmetry of the S demodulation curve response with out the need of a scope, sweep generator and matching pad.
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:Heck, you can even spot check alignment by using an off the air, moderate signal strength, FM stations signal.
: Query me if you need more info.
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:Reference thumbnail:
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:73's de Edd
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My response:
Edd –
Thanks for weighing in on the discussion. First, I have not installed the capacitor as I am waiting for other caps to arrive by mail and do them all at one time.

However, I am quite interested in your discussion on alignment. I only have a VOM meter and would like to “touch up” my alignment. Now this is what I think I can do.

For AM, I should be able to tune for a weak station and adjust the front end and IFs for a strong signal at the speaker.

For FM, I would think I could do the same in that I could adjust the IFs for a strong signal at the speaker.

However, with my circuit, do you see a way to adjust the S curve using a VOM? If necessary, I could readjust the meter for a zero center reading. But, if I could use my VOM, I would need to take into consideration meter loading since this is not a VTVM.

Anyway, would appreciate your comments on the above and any suggestions.

The schematic for my radio can be found at: http://www.nostalgiaair.org/PagesByModel/652/M0016652.pdf

Thanks,
Jerry
1/14/09
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1/21/2009 6:43:45 PMEdd

Guess this post was so small that I just zipped past it.

Now, I need info on that VOM, as per it being in the 20K + input Z such as Simpson 260’s and triplet ‘630’s are ?

Also, any chance that you have a digital voltmeter, as I can suggest a work around. . . . I have devised. . . . to circumvent its
“constant digit bobbling” .

OR, any chance of borrowing a VTVM if an owner is known in your area.

It makes the interpolation of the negative and positive swing on reading voltages easier when voltage can be adjusted to the center of the scale.

BTW, attempted adjustment of a VOM “to center scale” is not kosher, as that is merely a minute, very limited mechanical corrective mechanical movement of the frontal hairspring, on a d’;Arsonaval type of meter movement.

Too much movement upscale and you nonlinearly work against the companion symbiotically counterbalanced hair spring at the rear of the meter movement.

73's de Edd

1/23/2009 5:58:13 PMJerry(70172:70121)

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:Guess this post was so small that I just zipped past it.
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:Now, I need info on that VOM, as per it being in the 20K + input Z such as Simpson 260’s and triplet ‘630’s are ?
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:Also, any chance that you have a digital voltmeter, as I can suggest a work around. . . . I have devised. . . . to circumvent its
: “constant digit bobbling” .
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:OR, any chance of borrowing a VTVM if an owner is known in your area.
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:It makes the interpolation of the negative and positive swing on reading voltages easier when voltage can be adjusted to the center of the scale.
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:BTW, attempted adjustment of a VOM “to center scale” is not kosher, as that is merely a minute, very limited mechanical corrective mechanical movement of the frontal hairspring, on a d’;Arsonaval type of meter movement.
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:Too much movement upscale and you nonlinearly work against the companion symbiotically counterbalanced hair spring at the rear of the meter movement.
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:73's de Edd
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Edd –
Glad you found the post. My input Z is 30,000 ohms/volt DC and 10,000 ohms/volt AC. I guessed that my VOM meter movement would be unsatisfactory.
Anyway, perhaps you could answer the following. If I had the correct type meter, can my AM and FM be adjusted without signal generators? If so, can you advise? Please see schematic link from previous post.
Thanks,
Jerry
1/23/09

1/26/2009 6:16:59 PMEdd(70333:70172)

O-Kay then , for an alignment check of that big ‘ole receivers chassis, lets start with the AM section and looks like you will be
needing to get yourself a hex alignment tool. . . .aka. . .”diddle stick” that fits those IF t-formers slugs. . . . .nope….. an Allen wrench won’t fill the bill.

Next fire up the set and tune into a stronger AM station about mid band at 1000 KHZ and connect DC metering positive lead to
chassis ground and the negative lead will initially connect to my mark up [B] and then [A] and rock the tuning condenser on

that station until max reading is obtained on that reference station each time and then log down both .

Typical expected voltage level could be -5VDC on upwards to -40VDC for a powerhouse station .

Next move the negative lead metering to [B] and then ground [A] to chassis ground with a test lead.

Peak the tuning condenser on that same referencing station and see how much heftier the reading is now.

Will be waiting for the readings in order to proceed and also need you to consult the URL link below to see which station might be receivable with the strongest 910 KHz signal at your location. . . . which just possibly might have to be at nighttime.

SCHEMA REFERENCING:

URL REFERENCING:

About center page are the Town / State columns, until you eventually get down to Canada and Mexico.
> Me. . . ME. . .CLICK ON ME !

73's de Edd

1/26/2009 8:15:26 PMJerry(70338:70333)

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:O-Kay then , for an alignment check of that big ‘ole receivers chassis, lets start with the AM section and looks like you will be
: needing to get yourself a hex alignment tool. . . .aka. . .”diddle stick” that fits those IF t-formers slugs. . . . .nope….. an Allen wrench won’t fill the bill.
:
:Next fire up the set and tune into a stronger AM station about mid band at 1000 KHZ and connect DC metering positive lead to
:chassis ground and the negative lead will initially connect to my mark up [B] and then [A] and rock the tuning condenser on
:
:that station until max reading is obtained on that reference station each time and then log down both .
:
:
:Typical expected voltage level could be -5VDC on upwards to -40VDC for a powerhouse station .
:
:
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:Next move the negative lead metering to [B] and then ground [A] to chassis ground with a test lead.
:
:Peak the tuning condenser on that same referencing station and see how much heftier the reading is now.
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:Will be waiting for the readings in order to proceed and also need you to consult the URL link below to see which station might be receivable with the strongest 910 KHz signal at your location. . . . which just possibly might have to be at nighttime.
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:SCHEMA REFERENCING:
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:URL REFERENCING:
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:About center page are the Town / State columns, until you eventually get down to Canada and Mexico.
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::> Me. . . ME. . .CLICK ON ME !
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:73's de Edd
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Edd –
Thanks for the return. I am in the process of replacing parts in the radio and want to take some time to check the reception after that. So, if you have the time, I have no trouble receiving your feedback for the complete AM/FM alignment. It would make it easier for me (and perhaps for you) versus going back and forth and waiting for a response. And, when you consider my alignment may have to be at night, I can’t always be sure I can be timely in waiting for a good evening signal and responding.
I can then review your alignment instructions before starting and get back to you if I have questions; it would give me a better feel of what to expect. This would also allow me the opportunity to review the alignment versus doing it piecemeal and perhaps running into some problems. Your responses are easy to follow, so I should have no problem even if you need to make some assumptions on what I should expect to see.

Thanks,
Jerry
1/26/09

1/28/2009 1:17:42 PMJerry(70434:70333)

Edd –
You probably know that your schematic is not quite the same as my radio. See link: http://www.nostalgiaair.org/PagesByModel/652/M0016652.pdf
Although I can see the similarities, my concern was when I align the FM discriminator for the S curve, will your FM alignment instructions take that into account in my circuit?
Jerry
1/28/09

1/29/2009 4:25:35 PMEdd(70484:70434)

Sir Jerry:

In agreement, on your getting the final chassis work completed, but then, my queries for voltage readings being experienced, were directed to zeroing in on the loading effect that your VOM exhibits to the circuitry, however, Lord knows the number of circuit alignments that I have done, while utilizing a lower Z of 20k meter loading, vice your less invasive 30K.

Odd on that quirk in the schematic now being utilized by me, as I thought that the one that I am using was specific to your set and I had initially provided it from a referencing of my own, with it not from this sites referencing.
However, if the one you see referenced in this sites Red Ryders is right on. . . .including the top of chasis layout. . . . we will start doing our schema referencing to it.

I do know that my little FM tuning thumbnail was that of a later , just slightly higher numbered chassis. BUT the use of a single load resistor shunting the 4 ufd summing capacitor in the FM detector circuitry remains the same on both circuits.

On performing meter FM alignment evaluation, one is dependent upon a matched resistor pair for that resistor, in order to then be able to acquire a precise center referencing for metering. I can precisely trim in a pair and then send them to you for the solution of that particular aspect.

I have no trouble receiving your feedback for the complete AM/FM alignment. It would make it easier for me (and perhaps for you) versus going back and forth and waiting for a response.

1. . . .I still consider it best, for the doing of the AM evaluation initially.

And, when you consider my alignment may have to be at night, I can’t always be sure I can be timely in waiting for a good evening signal and responding.

2 . . . .Now, in your consulting of the stations chart referencing, which 910 AM station seems most likely to be receivable in your area ?, fortunately, in my locale, I have a 1 KW local, so it’s no problem in my getting a PREEEE-cise alignment referencing source.

3 . . . .I still need to know how strong of a developed negative AVC voltage that you are receiving on the primary AVC buss at test point [B], in order to see if it would be additionally necessary to ground out the upstream AVC buss at [A] in order to let the front end gain run rampant, thereby, further upping the derived AVC bias in that manner.

Standing by. . . .

73's de Edd

1/29/2009 10:48:06 PMJerry(70503:70484)

Edd –
Let me address your comments and perhaps you can still offer your suggestions.
"Lord knows the number of circuit alignments that I have done, while utilizing a lower Z of 20k meter loading, vice your less invasive 30K."
Yes, I would think my 30k loading would not be a problem.
"However, if the one you see referenced in this sites Red Ryders is right on. . . .including the top of chasis layout. . . . we will start doing our schema referencing to it."
I assume the Red Ryders schematic you mentioned is the one you included in your earlier e-mail. If it is, then it is not correct including the top chassis layout. My previous schematic link is the correct schematic and chassis layout.
"I do know that my little FM tuning thumbnail was that of a later , just slightly higher numbered chassis. BUT the use of a single load resistor shunting the 4 ufd summing capacitor in the FM detector circuitry remains the same on both circuits."
I’m sorry, I don’t have a reference to the load resistor information you mentioned. Perhaps you can repeat it for me.
"On performing meter FM alignment evaluation, one is dependent upon a matched resistor pair for that resistor, in order to then be able to acquire a precise center referencing for metering. I can precisely trim in a pair and then send them to you for the solution of that particular aspect."
That is nice of you to offer. Can you provide me with the values of the two resistors?
"1. . .I still consider it best, for the doing of the AM evaluation initially.
3 . . . .I still need to know how strong of a developed negative AVC voltage that you are receiving on the primary AVC buss at test point [B], in order to see if it would be additionally necessary to ground out the upstream AVC buss at [A] in order to let the front end gain run rampant, thereby, further upping the derived AVC bias in that manner."
I can see your point. However, it was my hope that your alignment instructions would be something I could use in the future. Also, do to my reception, when I am ready to align my set, I could very easily have a voltage reading that would be different from the reading I gave you. Saying that, is it possible to state two conditions? That is, if the AVC voltage is equal or greater than a certain voltage do “this.” If it is less than a certain value, then do “this.” Or, maybe there is a “work around” whereby the value of the AVC voltage would not be that important.

Now, this is my current situation. I have been doing this work in our family room. Because of obvious reasons, I need to clean up my work area and am not sure when I can get back to the radio. So, I don’t want to lose this opportunity of your contact and not have the alignment instructions available at a later date. If at all possible, would you still consider offering me your instructions, knowing that I may have to work with some assumptions? I am familiar enough with what you are doing, so in areas where there might be a concern, I can interpret and use proper judgment on the comments you may make.
Thanks,
Jerry
1/29/09