The radio after the hiatus
Article by W4TI Diehl Martin
In 1990 I got sick of ham radio and sold my HF station, a perfectly good TS-430S, with CW filter, and external power supply/speaker kit, along with a Heathkit SB-200 kilowatt linear amplifier. The antenna situation where I lived was awful, and there was no good way, it seemed, to solve the problem. For various reasons, I lost interest, and sold all of the HF equipment. That didn’t last long, though. In 1991, I decided that I could solve some of the problems, and replaced the old station with an Icom IC-735, along with an MFJ-989C antenna matching network. I also figured out that I had a good enough location to install an HF vertical antenna, and installed a Cushcraft V-7 groundless vertical. So I was back on the air.
In 1991, the IC-735 was at the end of a very long production run. Icom had been making these for nearly eight years, and the IC-735 was a mature design. Because it was discontinued, I got a better than usual price for the radio. The IC-735 was one of those radios that you would see in the non-big-gun DX stations pictured in QST and CQ. It was a cost-effective solution for those who needed a competent rig, and needed it to not cost too much. This was nothing fancy, but it always worked when I turned it on, and sounded good on the air. I kept this radio from 1991 until 2004, when I sold it to pay for the first big round of bills from my cancer surgery.
Excellent Transmit Audio â€“ The Icom IC-735 had good punchy transmit audio, when combined with the microphone that came with it. Icom had settled on high-output amplified electret microphones, and as long as the user stuck with one of those, the radio sounded very good. It could be heard through a crowded pile-up. For SSB there were two cascaded SSB filters, which allowed Icom to include an RF speech processor in the IC-735. This boosted the average transmitted SSB power significantly, without widening the transmitted signal at all. For SSB, it was a fine transmitter.
Pretty Good SSB Receive â€“ The Icom IC-735 was the first radio I ever owned which had two cascaded IF crystal filters, with the ability to shift the frequency for one of the IFs, which could be used to narrow the received bandwidth without buying any more filters. This only worked for SSB, unfortunately, as when the CW filter was engaged, there was no second CW filter to shift. For SSB it was a good receiver for its day. It certainly outperformed the TS-430 I had before it in this regard.
Simple Controls â€“ The Icom IC-735 did not have a lot of features to control, and all of them were accessible from the front panel. The usual controls were out there in front, but then Icom put a little transparent gray cover over a bunch of tiny controls for those things which were lesser-used. Unfortunately, this included such things as the switch for the CW filter, microphone gain, and other commonly used features. IF someone were using the IC-735 mobile, strictly on SSB, that little door would have been no real problem, but for the user who used all of the radio, that door became a weak spot in the design. If you look at these on eBay, you will find that many of them no longer have the little door, it having been lost long ago, as some user simply removed the door as a useless thing, or broke it, since it was made from really cheap plastic. Furthermore, some controls were simply too small for their function. An example of this is the notch knob, which controlled a tunable notch to get rid of carriers and such. The problem is that the knob is so small, and the tuning so finicky, that it was simply too much trouble to tune out the occasional carrier.
Full Break-In CW â€“ sort of anyway. The Icom IC-735 could be set to operate in a full-break-in mode, and if the user were not excessively fast, it did an OK job. The limitations were the relays in the T/R circuitry, which had to follow the keying. The relays were rather loud, and the keying waveforms were not particularly good in full-break-in mode. Furthermore, the receiver did not recover between dits, and so what the operator got was pretty close to full-break-in, but not done particularly well. At 10 words per minute, it worked well enough; at 25 words per minute it might as well not have been called full break-in.
Mediocre CW receive filtering â€“ I installed the proper CW filter in the Icom IC-735, and it did help with CW reception in a crowded band. however, there was a lot of â€œblow-byâ€ and the ultimate rejection of the CW filter seemed to be less than 30 dB. Furthermore, the Pass Band Tuning did not work with CW, as the 2nd IF filter in the CW mode was the normal SSB filter. This CW filtering issue was the single most annoying behavior of the Icom IC-735.
As a basic radio, the Icom IC-735 was a reasonable choice. If the operator used only SSB (or FM for that matter) the radio did a pretty good job. Certainly, it was a good buy for the price. Any CW operator, however, would find that the Icom IC-735 was lacking in features which are really needed for use in today’s crowded bands.