[Hammarlund] New to Hammarlunds

[Greg Mijal]

Welcome to the wonderful world of HQ 170A.
In my expereience, both of my old HQ 170's drifted.  It's just the way it is 
with the old girl.  The question is how much drift you are expereincing. 25 
hz every 3 - 4 minutes is pretty much normal.  A cap change won't get you 
very far.  I suggest that if you really want to dig into try a fan that 
sucks out the heat.  Place it in the area by the vfo tube and see what 
happens.  If the drift slows down, bolt in the fan and use it.  If no effect 
is noticed then it's something else like a slightly goofy part in the osc 
circuit.  Every time my airconditioning unit turned on, my 170 would begin 
to drift at an accelerated rate.  The Hallicrafters SX 101A is pretty 
stable.  Better construction and always on vfo tubes and a damp chaser. 
Occasionally it would go Ping! Zoop! when the refrigerator compressor turned 
on.
Good luck and welcome aboard.
Greg
WA7LYO
Kinston NC

----- Original Message ----- 
From: "Mitch" <mskobier at charter.net>
To: <Hammarlund at mailman.qth.net>
Sent: Saturday, April 09, 2011 12:34 AM
Subject: [Hammarlund] New to Hammarlunds


> All,
>    I have been a ham for a little over 25 years. I first became interested 
> in radio when I was given an old Halicrafters S-38 when I was about 10-12 
> years old. I fondly remember staying up late listening to broadcasts from 
> all over the world on that old thing.
>
> I have recently decided I wanted to put together a vintage 
> transmitterr/receiver setup. I already have a Heathkit DX-60 and matching 
> GH-10B VFO I aquired some 15+ years ago. I took a chance and purchased an 
> Hammarlund HQ-170A off of Ebay to go along with it. Once it arrived, the 
> first thing I did was replace the hard broken off electrical cord. I 
> replaced it with a three prong grounded plug. Tying the ground wire to the 
> chasis. I then removed all the tubes, cleaned the chasis of years of 
> accumulated grime, then brought the power up via a variac slowly over the 
> period of several hours. No smoke! I reinstalled the tubes and applied 
> power. the receiver came to life with a hiss, then I spent the next 
> several hours tuning in various SSB signals across the spectrum. This 
> thing is really sensitive and it easily can tune in on one signal on a 
> crowed band. Needless to say, I am quite impressed with this receiver.
>
> There is one issue with the receiver. Even after giving it an extended 
> warm up (days), it drifts quite noticeably. Making some crude comparision 
> test with my IC-756PRO, the 170 drifts about 25hz in 3-4 minutes. 
> Primarily it is drifting upwards in frequency. This is on the 80m band. 
> 20m doesn't appear to drift quite as bad. It does drift, though. In my 
> research on the internet, there appears to be a fix for this drift. 
> However, the BAMA archive, where this information is rumored to be located 
> has been down for several months, and I can not seem to find the necessary 
> information anywhere on the net. Does anyone on this group have the 
> particular information on how to fix or at least reduce the drift issue 
> with this receiver? It also appears from my research that the issue is 
> caused by a couple of temp compensating capacitors. The question is which 
> ones, and what temp coefficient capacitor do I replace them with? I have 
> the manual for the radio with schematic. In studing the part
> s list and schematic, it appears there are only about 5 or 6 capacitors 
> that could possibly be the cause. Of course which one(s) is the question.
>
> Anyway, thanks for being here. Any and all help will be greatly 
> appreciated.
>
> Mitch KJ7JA
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