Re: [RTTY] More on RTTY Frequency

[Kok Chen <chen@mac.com>]

On Aug 29, 2004, at 8:16 AM, Dick Kriss, AA5VU wrote:
> He came back saying he was reading
> 14085.3.  I thanked him for sharing and after the QSO I noted my 
> Kenwood
> TS-570D(G) was displaying 14089.33.

His/your reference oscillator may be off.  Could be both :-).

In fact, I had just yesterday opened up my FT-1000MP and adjusted my 
TCXO.   I'd not bothered to check since upgrading the rig with the 
TXCO-6 years ago and when I recently checked, I'd found that it had 
drifted by 70 Hz.

A TCXO only assures temperature stability, not absolute dial reading 
unless you calibrate it against a known good source.

A good way for us RTTY guys to figure out how far off the reference 
oscillator is, is to place your rig into RTTY mode (or AFSK etc) and 
then tune precisely to 10.000.00 (or whatever Excel spreadsheet you are 
using says the dial reading should be :-).   If you can, don't tune 
with the rig's VFO dial, either key the frequency in from a keypad or 
use computer control to set the frequency.

With the rig in RTTY mode, WWV's carrier should now appear where the 
mark tone should be.  You can then watch how far off the tone is either 
on a cross ellipse display, a spectrum or a waterfall display.  Adjust 
the reference oscillator until WWV's carrier is smack on top of the 
mark tone.

You can of course do it by zero beating WWV by ear in LSB or USB modes, 
but you can do it easier with the tools we RTTY'ers already have.

73
Chen, W7AY

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