Re: {Collins} Looking for connection info for Heath SB-620 scanalyzer for use in 75S-3B



 Maybe this will help... Although it's for the R390...

Dave WA3HSC

I dug out a letter from Reid Wheeler on panadapters and read through HSN 22
on hooking up SB-620's to the R-390A via pin 1 on V204. I made a short test wire
(unshielded for the time being) with two 4.7pf caps in parallel since I couldn't find
a 7pf anywhere in town. The HSN method uses the 7pf cap and the manual
suggests a 12pf. So, I was hoping that 9.4pf would be in the ballpark for a temp
connection. I have just gone back through some of the saved messages from the
list on hooking up panadapters and found that I had overlooked comments
recommending a 0.01ufd/600v blocking cap from several people. This is the
point where it could be coincidence or attributed to my hookup,but I lost all
audio at some point of fiddling with the panadapter trying to get a good signal
on the scope. I got some sort of signal, but nothing like expected. What little
audio I heard sounded like crossover bleeding through and when the RF is up all
the way on a killer station the distortion was terrible. I swapped out the audio
module and the problem was fixed. I found that R-263 had burned the bottom of
the circuit board black. I'm kinda glad to replace that audio module as I also
found V601 and V602 bad again. It now seems to go through those tubes
regularly.


 "A simple way to take measure of a country is to look at how many want
 in... And how many want out." Only two defining forces have ever offered
 to die for you:
 1. Jesus Christ
 2. The American G. I.
 One died for your soul, the other for your freedom.



---------- Original Message ----------
From: Bob Tufts <rbt@xxxxxxxxxxxxxxx>
To: collins@xxxxxxxxxxxxx
Subject: {Collins} Looking for connection info for Heath SB-620 scanalyzer for use in 75S-3B
Date: Wed, 08 Jun 2011 01:06:19 -0400

Hi people. I just picked up a Heahtkit SB-620 "scanalyzer" with the 
corect 455 khz coil for Collins IF, but it did not come with a manual.

Despite many internet searches I could not find the details on how to 
tie into the IF mixer stage ahead of the filters so I could use the 
panadapter function   I plan to use the spare phono jack on the back, 
but any recommendations on isolation caps/resistors to give a good 
signal but not adversely load the IF stage? I did see some brief 
comments (not related to Collins use) talking about choosing non-lossy 
coax. I also found an article where someone was converting a SB-620 
setup for 455 khz back to Heathkit 3395 khz IF and they had added a 
transistorized isolation buffer amp (but inside the SB-620).

I welcome any recommendations/experience.

-Bob WA1KPA


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