[Hammarlund] Dirft Fix/Cure for HQ-170A (VHF) and HQ-180A

[Carl]

Glad to see you made it here Chuk and hope you find that elusive HQ-170A 
VHF.

All good info from Al and I'll add that a NOS JAN 6C4 seem to be less 
problematic in that socket than others. Thats not to say a good used tube 
wont work as well but its more a gamble.

Id check the filament voltage and the B+ and if either seems high check your 
line voltage as in many areas it runs 123-127V. I run my HQ-180 which has an 
always on filament transformer added with a 12V bucking transformer. Drift 
is very low and so is the heat generated.

Carl
KM1H

----- Original Message ----- 
From: "Al Parker" <anchor at ec.rr.com>
To: "Chuck Pool" <aa5wg at yahoo.com>
Cc: <hammarlund at mailman.qth.net>
Sent: Thursday, October 21, 2010 7:32 PM
Subject: Re: [Hammarlund] Dirft Fix/Cure for HQ-170A (VHF) and HQ-180A


> Hi Chuck,
> Hammarlund issued service notes for the HQ-170 series, which also
> applies to the -180's. <http://www.hammarlund.info/hq178svc.pdf>
> Nothing specifically adresses drift in those notes, but the -170A and
> -180A's had changes which do reduce drift, and are not noted for having
> drift problems.
> Before I continue, let me ask, do you leave your 170A or 180A plugged
> in to a live outlet at all times?  The main differences made in the A
> models was to leave the filaments on at all times for one oscillator and
> it's mixer tube.  That greatly reduced warmup drift.  One other change
> was to replace the HV rectifier tube with silicon diodes.  THis reduced
> one fairly large source of heat inside.  They did not change the power
> transformer when that change was made, so the resulting B+ was a bit 
> higher.
> If you are still having drift problems, I'd try, first wiggling to see
> if that makes changes, then changing oscillator tubes and mixer tubes,
> one at a time, to see what difference you find.  You might also loosen
> and retighten all chassis screws, particularly those with ground lugs,
> including tube sockets.  YOu might put a drop of DeOxit on the sliding
> contacts on the variable capacitor chafts, buth main & bandspread.
> I hope this helps somewhat.
> 73,
> Al, W8UT
> www.boatanchors.org
> www.hammarlund.info
>
> "There is nothing -- absolutely nothing -- half so much
> worth doing as simply messing about in boats"
> Ratty, to Mole
>
> On 10/21/2010 6:52 PM, Chuck Pool wrote:
>> Hi to all Hammarlund fans:
>> What reference or information (bulletins) are available that addresses 
>> the drift cure/fix for the HQ-170A (VHF) and HQ-180A and all other 
>> possible issues?
>> Thank you to all.
>> Chuck - AA5WG
>>
>>
>>
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