[TenTec] TT Synthesizer Accuracy (Orion 2)

[Ron Castro]

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 at contesting.com] On Behalf Of Jim M. via TenTec
Sent: November 12, 2015 1:51 PM
To: tentec at 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 calibrate it close to the middle of the HF frequency range, like 14.4 Mhz.

Thanks, Jim N4BE
_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec