[Hallicrafters] SX-88 part location?

[Roger Shultz]

Hi Greg,

That would be very much appreciated! 

There was a 10K CTS in there but it was open so I could not get any
information from it. With a 10K linear, it does exactly what you describe
with only about 1 division of adjustment. 

The shaft length can be accommodated with a coupling which is what I did
because Mouser did not have the full length shaft in the mil-spec linear pot
I purchased.

I'm still puzzled about the 330K R83 resistor to ground off the pot. It
doesn't seem to matter if it is there or not and it was missing. The circuit
is similar to that in the SX-100 which I have.

No hurry, and thanks again for the information as it makes so much sense!

73, Roger, NJ2R

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of WA1KBQ at aol.com
Sent: Monday, November 08, 2010 9:56 PM
To: hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] SX-88 part location?

Roger,
 
Sounds like you might have an early one. I think there was a bulletin  
issued that changed R-83 to 15K and corrected a mistake in the  schematic 
concerning how the RF gain control is connected. The RF gain control  is a
10K 
reverse log taper made by CTS I think. Reverse taper controls with a  2.250"

shaft are hard to find. You might get by with a linear control but the  
control function will be bunched toward one end of the rotation. I am not
close 
to the info at the moment but I will look it up and send further details. 
 
Regards, Greg
 
 
In a message dated 11/8/2010 3:38:21 P.M. Eastern Standard Time,  
nj2r at verizon.net writes:

I'm  working on a SX-88 that has a defective RF gain control. Someone
previously  "modified" the pot toasting it and in the process removed R-83, 
a
330K 1/2  watt resistor. The picture in the instruction manual does not show
where  this was mounted nor can I find where the ground end may have  been
connected.

I can of course provide a ground point but it would  be nice to know where 
it
was originally connected.

A second question  is that the instruction manual parts list does not 
specify
if the RF gain  pot is a linear or audio taper pot. It doesn't specify for
any pot  including the volume control what taper if any is intended.

Thanks for  any advice.

73, Roger,  NJ2R

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