 |
|
Icom IC-735 (IC 735 IC735) Xmit Mods
|
| |
I don't have either one of my 735's open and I can't seem to find the
precise location or information but roughly...
There are two diodes, D30 &D31 (or maybe it's D32&D33 D34&D35 I can't
remember) located toward the front center of the board containing the
CPU. The diodes were end mounted with yellow insulation over the end of the
leads away from the board. Cutting these diodes out of the circuit enables
broadband transmit. My radios were purchased new in spring of 1989 so
I don't know if they acurately reflect current production units.
This is a particularly nice feature since it allows wide coverage when
used with transverters. I use my 735's with my 144MHZ - 10.368 GHz transverters
with the radios operating in the 20-30 MHz region. It allows 10 MHz of
all-mode coverage on every vhf-uhf-uwave amateur band.
>
> Do you have any documentation and/or suggestions on how to build or
> design the 50 MHz through 902 MHz units ?
>
I don't have anything explicitly written but it is very much along
the lines of the microwave stuff I showed.
The LOs are partly there already:
Band LO circuit
50M 30M 3 X 10 (2n5179 tripler from 10M)
144 120M I'm presently using the 100 MHz Xtal circuit
with a 120 M xtal but 6X20M with filtering
would work too.
220 200M 2X 100M (single stage of 2n5179)
420 410/420 Just like 260M LO shown
900 620M Like 1010M 6th harm of 100M and 20M PLL reference
Only 420 and 900 even need to use another of the PLL boards. The others
just take a single stage. I have 50,144 and 220 done. 400 is sitting
90% completed. I have PA bricks for 50 and 400 waiting to be used.
As I said, 144 and 1296 have been running for years.
I build the RF decks in metal "shoeboxes". I pipe the LO and IF(with tx
switching as DC on the line) to each deck which lets me remote them
if I want to. The only thing I really need to add that I haven't is an
ALC line coming back from each PA to control the 735 so that I keep
things linear. Linearity hasn't been a problem but like any of the
current commercially available transverters it is possible to overdrive
things.
|
|
|
