[Hammarlund] HQ-170A drift

[Bill Cromwell]

On 05/16/2014 09:27 PM, Kenneth G. Gordon wrote:
> On 16 May 2014 at 18:28, John Boyle wrote:
>
>> I recently bought an HQ-170A at a hamfest.  It´s in good condition but has the
>> well-known frequency drift in spades.  I´ve read comments about the
>> instability of both the capacitors and inductors in the oscillator section.
>> Would some new high-quality capacitors help and if so, which ones?  Any thoughts
>> on this matter would be appreciated.
> My thoughts:
>
> Since the HFO is a 6C4, I would buy some of the military versions of those off
> eBay and substitute tubes until I get one that is stable.
>
> Ken
>
When I had my HQ-145 I got rid of the drift by swapping a better 6C4 in 
the VFO. The old tube checked good on a tube tester but that cured the 
problem. I was able to use the 145 on Navy MARS SSB nets and it stayed 
put with about a 15 minute warmup. Get several and try them all. Sort 
the "bad" ones out for use in some *other* function (audio preamp 
maybe). Put the "good" ones in a safe place for future VFO use.

73,

Bill  KU8H