[aprssig] Re: Does anyone have a fix for the 70cm tone encoder problem on the TH-7ag?
Stephen H. Smith
wa8lmf2 at aol.com
Mon Mar 19 01:30:31 CDT 2007
hamaddict2001 at yahoo.com wrote:
> Thanks for the response...that sounds feasible to me. Also if this is
> the problem I think it will not be too hard to correct.
> But why would the problem only manifest itself on 70cm and not 2m as
> Thanks again,
At UHF, the transmitter synthesizer VCO (Voltage Controlled Oscillator)
is either running at the VHF frequency and then tripled, or the VCO is
running directly at three times the frequency that it is on VHF.
In either case, any kind of electrical or mechanical disturbance
(possibly the VCO tuned circuit is microphonic; i.e. sensitive to
vibration or mechanical shock) is going to be three times as pronounced
on UHF as it would be on VHF.
Stephen H. Smith wa8lmf (at) aol.com
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