[Hammarlund] hammarlund displays

[Joel R. Hallas]

Mike,

I don't know where to get one, but I would say that "tracking" may be a bit of a
red herring. I believe that these units count the frequency of the HF osc and
then add (or subtract as appropriate) the IF frequency to indicate received
frequency. As such, there are only three potential  error problems that I can
imagine;

1. the counter time base is off, not too big a problem if derived from a
crystal.

2. The IF is misalligned to a different frequency than you expect. This would be
the case if you alligned your 455 KHz IF to 460 KHz, for example. Then you would
have a constant 5 KHz error. This seems unlikely since you would notice, I would
think, that your crystal filter didn't work.

3. And this may be where "tracking" comes from. You are listening (or worse
aligned) to the image frequency. This can be a problem on bands 14 MHz and above
on single conversion sets. If you just align at both ends, you can even have it
right at the low end and wrong at the high. A few stations "on the wrong
frequency" by twice the IF should tip you off.

Other than the above, it should be just as accurate as any "modern" digital
display receiver, IMHO, or did I miss something?

73 and GL,
Joel Hallas, W1ZR

Mike Taylor wrote:

> Hi group! Awhile back there was several days of discussion about dial
> tracking. Someone mentioned using an outboard digital display and I've heard
> they are available. I don't know who offers them. But I seem to remember
> reading somewhere that these things are only as accurate as the tracking of
> the receiver's oscillator. In other words, if the dial is reading 50khz
> high, so will the digital display. Both of my Hammarlunds track perfectly
> but a digital display might be neat to have on my HQ-180 as the dial
> divisions get rather "tight" above 15mhz. Can anyone shed any light on this
> subject? 73's...Mike
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