[Premium-Rx] Receiver Frequency Display Accuracy & Calibration

[Gary Geissinger]

Ahmet,

I am in the process of writing an article for QST on a related topic,
"Aligning a Synthesized Receiver or Transceiver by Ear".  Who knows if
they will publish it.

This approach assumes the ham or SWL has good ears.  Most CW and RTTY
ops are pretty good at things like this.

Basically it goes like this.  In a conventional (high IF) fully
synthesized receiver (not an Elecraft K2!) the errors due to
misadjustment of the master oscillator are very systematic (I'll skip
the math here).  If you program into your receiver the series of WWV
frequencies with an offset so that you can hear the beatnote, like:

2.501
5.001
10.001
15.001
20.001

or:

2.499
4.999
9.999
14.999
19.999

you should hear the same beatnote for all frequencies.  If the master
oscillator is not correct, the beat note will either constantly increase
or decrease as you move up the series.  The error is pretty obvious,
especially if you program the frequency series into the memory of the
receiver and move between them quickly.  When the master oscillator is
adjusted correctly, the beatnote will be constant for all of the WWV
frequencies.  This procedure has been used on:

HF-1000
WJ-8712
IC-735
IC-706
IC-756
IC-756PRO
R-8B
R-75

with consistently good results.  The adjustment is very slight; go slow
and carefully when you do this.

Some receivers, either older or less expensive, are not fully
synthesized.  In those receivers, this procedure can still be used, but
the "unlocked" oscillators will still need to be adjusted manually.  The
R-71 is a good example; this procedure worked on it, but the BFO
oscillator needed independent adjustment.

If you can hear at least 3 WWV frequencies, this approach yields very
good results.

Gary

  




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-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org] On Behalf Of Ahmet Gundes
Sent: Sunday, October 03, 2004 5:59 PM
To: Premium-RX
Subject: [Premium-Rx] Receiver Frequency Display Accuracy & Calibration


Hi everyone.

I would like to check the Frequency Display Accuracy of an HF Receiver.
Does anyone have any idea how we can check Receiver Frequency Readout
Display accuracy. What would be a good method, without the use of
specialized equipment, to verify that the 
Receiver freq redout is displaying the actual tuned frequency. Naturally
I'd like to get 1Hz accuracy if possible.  Can WWV, 
WWVH ,... time stations be used in doing this ?

It would be interesting to hear from anyone who tried this before or
have a good idea on how to do it.

Thank you,
Ahmet Gundes
-- 
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