[Hammarlund] HQ-180A 60 KHz IF Problem - Suggestions?

[Steven Reed]

Wade, interesting you should bring that up -- I've been desperately looking for mistakes on my part and hope I'd find it (and still hope I do!).  There's nothing worse than getting deep into a bizarre problem like this only to find out -- after many parts replacements and long hours at the bench -- that I've goofed something up from the start.  Wouldn't be the first time or the last time for me.  This is why I've been hovering over this for so long (been at this for a couple of weeks -- looking at the same problem over and over again, hoping to find another angle).  Anyway -- sadly -- the correct slugs are being tuned.  

Steve.

On 2/2/22, 10:49 AM, "wmacleod2 at sympatico.ca" <wmacleod2 at sympatico.ca> wrote:

    Hmmm very unusual that all tuned sections respond the same way. 
    The only thing they have in common are the ganged switches...unless someone
    changed their capacitors.

    Are you sure you are tuning the correct slugs? 

    I get mixed up some times and when nothing moves I stop and realize the
    mistake,.


    Wade






    -----Original Message-----
    From: hammarlund-bounces at mailman.qth.net
    <hammarlund-bounces at mailman.qth.net> On Behalf Of Steven Reed
    Sent: Wednesday, February 2, 2022 10:28 AM
    To: Hammarlund at mailman.qth.net
    Subject: [Hammarlund] HQ-180A 60 KHz IF Problem - Suggestions?

    I've been busy restoring a beautiful old HQ-180A.  Previous owners have
    struggled with the IF of this radio and I localized and fixed the major
    smoking gun:  V7's cathode resistor had drifted from 68 ohms to over 400
    ohms.  I'm now left with the aftermath of all the fiddling and prodding
    that's happened to the IF section over the years.  The problem I'm now
    facing is that the 60 KHz IF section isn't resonant at 60 KHz and won't
    align correctly - I can't find a peak at 60 KHz in any of the IF
    transformers (T6 through T11).  The radio is correctly set according to the
    manual for this procedure.  However, if I vary the signal generator some,
    the transformers will find strong peaks around 54 - 56 KHz.  Been through a
    lot of steps trying to isolate this but keep coming up empty.  The entire 60
    KHz IF chain appears to be affected - injecting signals further down the
    line produces nothing different.  What would drive the resonant frequency of
    the ENTIRE 60 KHz IF chain down like this?

    73 - Steve, KW4H

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