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Re: GPS lock the FT-817 for transverter


Mike Olbrisch
 

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Heh heh heh ¨C as usual, the real answer is ¨C IT DEPENDS.

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There are a few manufacturers of various transverters.? Price-wise, they can go from below $100 to several $-hundred.? And in most cases, you get what you pay for.? Good designs and good components are not cheap.

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Truth, FT-817 frequency accuracy with the stock OSC is less of a problem than frequency drift.? The TCXO-9 will be more stable.? Perhaps more accurate, but the stock OSC can be close enough.? Temperature and voltage changes would be my main worry.

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You¡¯re never going to be portable with the accuracy and stability of a home station.? So many other factors must be considered, as in temperature rise or fall throughout the day, equipment temperature fluctuations due to heavy or light use, voltage fluctuations during TX/RX transients, and as the battery decays, and a host of other minor points that all add up.

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And of course if you are talking EME or SAT, Doppler will also be a consideration.? And Doppler shift is greater with higher frequencies.

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No matter what the cost, the equipment you actually have is better than the best gear that you can¡¯t afford.? Use what you have, and good luck.

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Mike ¨C KD5KC -- El Paso -- Texas.

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The canyons are calling, colorful and deep.? But I have promises to keep.

And miles to go still in my Jeep...?? And miles to go still in my Jeep...

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Big Bend JEEP Rear

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ADVENTURE:? The respectful pursuit of trouble.

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From: [email protected] <[email protected]> On Behalf Of nz8r@...
Sent: Friday, November 8, 2019 17:24 PM
To: [email protected]
Subject: Re: [ft817] GPS lock the FT-817 for transverter

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Pardon the inquiry.
I am interested in learning a bit more about upper microwave transverters and their operation.? ?

Do these typically mix the radio (say at 144mhz) as an IF to a multiplied oscillator??
If this is true, the errors would be? something like below:

FT-817 error? ? ? ? ? ? ?=? Ferror
Base oscillator error = Oerror
MultError? ? ? ? ? ? ? ? ?= Oerror * N
Total Error? ? ? ? ? ? ? ? =Terr
Osc's can self start pretty reliably up to about 100mhz....
Therefore N needs to be 100 to 150,? such a large N means Oerror needs to be really small--probably as good as technology will permit.


In the end this is Terr =? Ferror + MultError

It seems the Ferror is really tiny and MultError is huge.? ?
In other words, it seems to me the FT-817 errors are not relevant.

What am I missing as to spending money on fixing the FT817 error,? when 100 times the impact is in the Oscillator errors on the Transverter?

Thanks in advance,

Greg
nz8r

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