[Fwd: Re: [Kenwood] Dig. Freq & Parts for KW 599s]

[Dr. Gerald N. Johnson, electrical engineer]

Dr. Gerald N. Johnson, electrical engineer wrote:
> 
> A&A Engineering, I believe it is, has a kit for digital read out for
> many radio. You need to read three frequencies and add or subtract them
> to get the actually receive/transmit frequency. In most SSB radios there
> are at least three frequencies involved. There's the first mixer
> frequency which is often a crystal, then there's the local oscillator
> which mixes with the first IF signal, then there's the BFO (in the
> receiver) frequency or the carrier generator (in the transmitter). There
> are variations on the scheme. Some radios mix the local oscillator with
> the crystal, then use that result for single conversion. Some do double
> or triple conversion and you need to read all the mixer injections where
> signal changes frequency, including the last one in the receiver that
> changes the IF down to audio in the product detector.
> 
> You can't count the output on SSB and learn anything useful. Remember
> the output on SSB is a spectrum a couple KHz broad and it has no carrier
> transmitted. And because the voice isn't a continuous tone, there's not
> signal there constantly for the counter to count. All you can achieve
> counting the output of a SSB transmitter is random numbers.
> 
> Some counters have counted only the VFO frequency, then put in fixed
> offsets into the counter to account for BFO and crystal frequencies. My
> TenTec Corsair II does that. My Kenwood TS-130 does that. Gets a digital
> readout but you need a crystal calibrator to check it.
> 
> The easiest way to get a digital read out is to acquire a more recent
> radio than the antique twins. Otherwise use the twins as is. The analog
> readout was as good as the radio stability and more. Why try to make it
> into a silkier purse?
> 
> 73, Jerry, K0CQ
> 
> --
> Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
> Reproduction by permission only.


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