[Hammarlund] HQ-170A drift reduction progress

[Kenneth G. Gordon]

On 15 Apr 2011 at 12:48, Richard Knoppow wrote:

>      I found my S-600-JX drifted quite a lot when a 
> thermostatically controlled electic heater was being used. 
> This is a very old house

Ours is too: over 100 years. I have no idea when it was electrified, but much 
of the wiring (in NON-critical places) is still #14 knob-and-tube.

> and there is some reduction in 
> voltage when something draws a lot of power. Its the 
> filament voltage changing that causes the problem. The cure 
> was putting the receiver on a Sola constant voltage 
> transformer. Not all receivers are suseptible, for instance, 
> my R-388 does not change at all over a very wide range of 
> line voltage and does not have regulated filaments.

Many of my receivers don't change that way either. The Heathkit transceivers 
don't, for instance. Also, neither do many of my ex-military receivers. But 
some sure do. My HQ-110 sure does, for instance.

The only complaint I have about the Sola constant-voltage transformers I 
own is the loud hum from them. I find it very tiring.

Ken W7EKB