[TenTec] Frequency Misalignment Between VFO A and VFO B

[Marshall Stewart KA5M]

Here's what Paul Clinton at Ten-Tec has to say about this:

Because the two receivers have different tuning resolution there is a slight
difference in frequency, and the resulting heterodyne is what you are
hearing,
 
73,
Paul R. Clinton
WD4EBR
Service Manager
 
----- Original Message ----- 
From: Marshall Stewart KA5M 
To: service at tentec.com 
Sent: Sunday, February 17, 2008 3:59 PM
Subject: ORION II Question - Both Receivers Listening on Same Frequency


If I tune both receivers, the main and the sub, to exactly the same
frequency, say for example 14.010.000, mode LCW, BW set at 1000 Hz, and set
the AF gain for each receiver to about the same level, I hear an
"oscillation" or "beat" in either the speaker or headphones, whichever I'm
listening too.  (It is difficult for me to describe the "oscillation" or
"beat" sound I'm hearing, but it is like a flutter.)

It does not seem to matter if I use VFO A for the main receiver and VFO B
for the sub receiver, or use VFO A for both receivers.  Also, it does not
seem to matter if a signal is present or not on the frequency I am listening
to.  If I change the frequency of one of the receivers slightly, in 10 Hz
steps, the frequency of the "oscillation" or "beat" changes (gets slower or
faster.)

If I wanted to use both receivers for diversity reception, this sound would
be distracting.  Can you tell me what I'm hearing?


73,

Marsh, KA5M

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of Ron Castro
Sent: Monday, February 18, 2008 11:07 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Frequency Misalignment Between VFO A and VFO B

I have the same problem, which is documented on my web site at www.N6IE.com 
.  The receivers are not phase locked even though they use the same master 
oscillator.  The best I can figure is that the DSP runs off a crystal that 
is not exactly on frequency and, unfortunately cannot be tweaked.  Both 
"sides" of the two-channel DSP are operated off the same crystal (not the 
master oscillator), but the scheme may result in a difference of frequencies

of the two receivers unless the crystal is precisely on the correct 
frequency and that a deviation may cause on receiver to go up in frequency 
and the other to go down.

The result in my O2 is that the main and sub are 6 Hz different on all 
frequencies.

         Ron  N6IE
      www.N6IE.com


----- Original Message ----- 
From: "Kim Elmore" <cw_de_n5op at sbcglobal.net>
To: "Tentec Contesting List" <tentec at contesting.com>
Sent: Monday, February 18, 2008 5:32 AM
Subject: [TenTec] Frequency Misalignment Between VFO A and VFO B


> For some  time, I've noticed what seemed to be a very slight
> frequency misalignment between VFO A and VFO B when in the binaural
> mode (A in one ear and B in the other).
>
> On my O II it's noticeable even in the noise as what sounds like a
> beat note in stereo phasing when both VFOs are tuned to the same
> frequency. Last night, I chased this down and found that VFO B is
> about 6 Hz lower in frequency that VFO A. This isn't a terribly big
> deal, but is there a way to align the two, or are the master
> oscillators different so that the two drift around slightly as a
> matter of course?
>
> Kim Elmore, N5OP
>
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
> 

_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec