Subject: tx Mod For ICOM 735 The mod for gen/cov tx for the IC-735 involves removing D33 and D34 from the main board. You'll have to lift the PA module up to do this, locate the diodes and simply snip one end of each. Very simple, but it's amazing just how many screws need removing in the process! ============================================================================== 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. ============================================================================== I have finally got the remote control working on the IC735. The interface is home-made and uses just 2 transistors, 1 diode, 5 resistors, DB25 and a DB15(to get 5v from games port). The software is a major re-hash of VK7TM's FT757 effort in ARA. All functions are driven from the XT keyboard and the software allows scanning of a LARGE number of frequencies on the same or on different bands. The trials and tribulations of all this effort were NOT assisted in any way by the manufacturer's local office in Melbourne. A call for information was not very successful. (try it and see!) If you are contemplating the idea of turning your IC735 into a multi- channel HF scanner, I may be contacted @ VK3YZW BBS.. The software is suitable for use with XT/AT Clone... Available control functions: Send a new frequency to the radio from the keyboard. Send a new Mode to the radio. Select VFO A or VFO B. Select a different memory channel Enable the selected memory channel Write current Freq/Mode to selected memory channel. Write current Freq/Mode to last used VFO. Read/Edit/Use a frequency file from Disk. SCAN frequencies in a frequency file. The frequency files contain frequency/mode/description of station all of which is displayed on the screen when the file is active.