Jim:
The only accurate way to calibrate is to use the main VFO and WWV, preferably
15 or 20 MHz. Follow the directions for tuning the master oscillator found on
my website:
http://n6ie.com/TXCO%20Calibration.htm
The fan mod helps too, but it's not 100% necessary.
Ron Castro
N6IE
www.N6IE.com
Member:
ARRL
Redwood Empire DX Assn.
Northern California Contest Club
Northern California DX Foundation
Society of Broadcast Engineers
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim M. via
TenTec
Sent: November 12, 2015 1:51 PM
To: tentec@contesting.com
Cc: Jim M.
Subject: [TenTec] TT Synthesizer Accuracy (Orion 2)
I suspect this has already been hashed over in the past, but I need some
guidance. I use the TCXO calbration procedure found on the wiki, i.e. use
SubRx, tune to WWV, adjust TCXO for same tone on USB and LSB. But afterwards,
the Main RX seems to be off by 30-50 Hz depending on the frequency/band. I
also use a known calibrated signal source (an Icom TCVR) at various freqs to
confirm. Conversely, if I modify the procedure and instead listen to the known
signal source on the Main Rx set for say 14Mhz, all is well for that band but
then the Sub RX is off. Then lets say I use the known source to set the Tcxo
when receiving 28Mhz on the O2, then tune the O2 down to a lower band, it will
be off by 30-70 Hz depending on how far from 28Mhz I go. Seems like the O2
synth tracking is amiss. Is this normal behavior? My conslusion, unless
something is malfunctioning, is DON'T adjust the Tcxo using the Sub RX, but
rather using the Main Rx with a calibrated source. Then maybe calibr
ate it close to the middle of the HF frequency range, like 14.4 Mhz.
Thanks, Jim N4BE
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