[Hallicrafters] Aligning a S-76

[Jim Liles]

Ken,

Do you have the users manual with schematic?

Chris and Grant are right about the sense point.    

Step 1 50Kc:  V3 is removed.  The injection point is Pin 1 of T2 not L6.  There is no voltage on that pin of T2.  The sense point is AVC because you are aligning the .5Kc bandwidth position to anchor the 50Kc I.F. system.  The injection is un-modulated because it is the .5Kc position.

Step 2 1650Kc:  Askes you to use a modulated injection signal.  Read through it a few times after you get the 50Kc right.  It is essentially written to center the 5Kc wide 50Kc signal in the center of the wider 1650Kc pass band.  The radio is set to band 1 and a modulated 1650Kc signal is injected into the grid of V2 the first mixer simulating a signal from the antenna.  This step senses at the speaker leads because it is modulated and 5Kc wide.

There are no paper capacitors under the sub-chassis.  I would not remove it unless you measure a defective component.  You can measure all components from tube pins and under chassis connections.

Thoughts?

Kindest regards Jim K9AXN  




----Original Message----- 
From: Chris Farley via Hallicrafters 
Sent: Friday, August 07, 2015 10:25 PM 
To: hallicrafters at mailman.qth.net 
Subject: Re: [Hallicrafters] Aligning a S-76 


    
Grant is absolutely correct, they want you measuring voltage on the AVC line (with the AVC switch "off") at the junction of R48, R50, R51, and C51.  Sam's also suggests to remove the 1st Osc tube (V3) for the 50kc IF alignment.  I will snap a photo of the alignment instructions and send it to you directly.  (Pretty sure this list strips attachments?)
Additionally, this is Sam's set 143 folder 9 if you have access or can find it online someplace.  
Regards, Chris kc9ieq


Sent from my SMRTphone

-------- Original message --------
From: GRANT YOUNGMAN <nq5t at tx.rr.com> 
Date: 08/07/2015  7:49 PM  (GMT-06:00) 
To: Chris Farley <kc9ieq at yahoo.com> 
Cc: Ken And Susan Hittson via Hallicrafters <hallicrafters at mailman.qth.net> 
Subject: Re: [Hallicrafters] Aligning a S-76 


I think that measurement point is on the AVC line, not audio.  And no, there shouldn’t be any audio output from the speaker — all that misdirection may be because they simply want a load on the output  transformer.

Grant NQ5T


> On Aug 7, 2015, at 6:30 PM, Chris Farley via Hallicrafters <hallicrafters at mailman.qth.net> wrote:
> 
> 
> 
> Perhaps I'm missing something, but I don't think you should be hearing anything from the speaker during IF alignment...  Are the alignment instructions telling you to measure the audio output, or an RF voltage ahead of the detector?  I'll see if I have a Sam's on the S-76 when I get home...
> Regards, Chris kc9ieq
> 
> 
> Sent from my SMRTphone
> 

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