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Mods


Eric Freund
 

First I'll apologise in advance if someone has already tried, however I
couldn't see anything in the archives.
Second I buy my equipment cheap in places like HK so I dont have a Warranty
(so dont tell me about voiding it!)
Thirdly I haven't picked up my radio yet so its all a bit academic, but if
you look at the front panel schematic you will see 9 jumpers
user 1-3,
SRX, STX, EXP,
TS 0-2,
The latter 6 have * next to them implying they vary from model to model.
EXP have to mean Export? What about SRX,STX?
Has any body looked at these to see what they currently have and has
anybody tried changing them?
Some one also mentioned a mil version it that is true I would bet it has a
different micro (has to to get the temp spec!) so would also mean different
SW so if it is true and there is one one could just order the new micro as
a spare and replace it. Very easy mod!

Cheers
Eric.
P.S. I've only looked at the cct for about 5 min so I will now have a look
to see what the physical limitations on the unit really are.

-----------------------------------------------------------------
Eric Freund, Engineer.
Oilphase, Schlumberger Oilfield Aust P. L.
23 Brennan Way, Belmont,
Perth, Western Australia, 6104.

Tel : +61 8 9277 2000 Mo: +61 41 331 9396
Fax: +61 8 9277 3222
mailto:freund@...
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Eric Freund
 

Just for further reference having a look at the theory of operation I would
say apart from VCO limitations the radio would be able to operate from
100kHz to 470 MHz. Where the vco's drop out is going to be the limiting
factor. Apart from of course the firmware.
In VCO design a frequency range ratio of approximately 1.5:1 is a normal
design expectancy for a reasonable wide band VCO (please flame me if you
dont think this is realistic!) to 68-102-153-230-345-520! (allowing for the
68MHz 1st IF thats 100kHz-450 or so at least!)
So given careful design it is feasible that one could get full coverage.
The TX signal is modulated at 455kHz and then mixed up with 3x the REF to
generate an ~68MHz signal which is then mixed with the final VCO to get the
desired TX frequency. Which is the same as the RX range.

All very interesting.

Cheers
Eric.

-----------------------------------------------------------------
Eric Freund, Engineer.
Oilphase, Schlumberger Oilfield Aust P. L.
23 Brennan Way, Belmont,
Perth, Western Australia, 6104.

Tel : +61 8 9277 2000 Mo: +61 41 331 9396
Fax: +61 8 9277 3222
mailto:freund@...
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