"XVTR" setup for Frequency dividing Class D amplifiers on VLF

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  • Updated 7 months ago
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I have seen several posts from users trying to figure out how to drive an amplifier for 630 Meters and 2200 Meters.  Several amp options I have seen use Class D circuits that must be driven at twice the intended frequency.  

It has been suggested that users should simply set up a "transverter" definition to accomplish this, but this won't work correctly as it stands now because the simple frequency shift routine in the transverter setup does not account for the required frequency doubling by two.

The user could simply set one slice for a TX frequency of twice the RX frequency and use split, but it would be very difficult to accurately track the RX/TX frequencies.

My idea, if it can be implemented, would be to have a "transverter" or other band-set setup option with "Double TX Frequency" which would automatically double the TX frequency sent to the Transverter Port, but leave the Receive frequency alone, allowing the user to simply dial the intended 630 Meter or 2200 Meter frequency on their receiver as usual, but when in transmit, the TX frequency sent to the XVTR port would automatically be shifted by 2X, allowing seamless transceiving on those bands while using such an amplifier.

If the "2X" box is not checked, then there would be no frequency shifting and the rig would operate normally.

I don't want to ask if it is "possible" (It's just ASMOP - a simple matter of programming...[grin] ) ... but my question is "would it be practical to implement this?" 

An alternative method, could use two slices, and "simply" sync the second slice with a routine that doubled the "control" slice's frequency?  Someone might be able to do this with the API or CAT commands and macros?  

Although this idea pertains mostly to the 6000 series, it is possible that someone could implement the alternative method as a control macro for PowerSDR as well.

Ken - NM9P
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Ken - NM9P, Elmer

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Posted 7 months ago

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John AE5X

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There is a "X2" option for WSPR in WSJT-X. The next release of WSJT-X will include this functionality for JT9, JT65 and FT8 as well.

More details here:
http://ae5x.blogspot.com/2017/11/options-for-putting-signal-on-630-meters.html

73 - John AE5X
(Edited)
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Ken - NM9P, Elmer

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Yes, that is an important part of a total solution - which requires double shift spacing. 
But it doesn't solve the need for actually shifting the transmitter RF frequency x 2 and tracking the relative shift to maintain TX / RX matching.  i.e. a 2 KHz shift in the receiver frequency requires a 4 KHz shift in TX frequency (at double the frequency) in order to divide it back down by half and still be on the same frequency.