NEWBIE: Installing Icom IC-735 in sailboat

[Ray-Dianna]

Hello to all, I am new to HF radio, I was given a IC-735 and a AH-2 tuner. I would like to install this radio on my sailboat. I am thinking of a long wire antenna from mast to the radar arch, feed wire thru one of the arch legs with the tuner right below the arch leg. Lots of questions at this point. Would the arch become part of the feed wire/antenna setup? The arch has solar panels and a wind generator mounted on it but is not grounded, would I ground the arch to the RF ground point? Also because I cannot access all the required wireing that I have seen suggested, 10 or 8 awg tinned ground wire, could I use say 2 12 awg tinned wires taped and soldered together in place off. Also the 2-3" copper foil, is there a replacement wire that would be acceptable? And this is just beginning. I appreciate all your answers and help. Thanks in advance. Cheers Ray VA6DRK

[Jim Cate]

We used a 735 for years on our previous boat, and it was a pretty reliable rig, so likely no problems there. But, don't run your "feed wire" through the arch leg. That "feed wire" is part of the radiating antenna, and the tubing will block all of the radiated energy from that section and will likely cause tuning issues as well.

I don't completely understand the rest of your questions relative to the RF ground. The flat copper strap to a metal through hull, etc, is the best solution, but is often difficult to route. Many folks have substituted other conductors, typically multistrand copper wire of decent size, and found reasonable performance. We used one inch wide tubular shielding braid for a while, and had useful if not optimal grounding. It was plagued by corrosion and isn't recommended!

I suspect that KA4WJA will pipe up with far more info, but I thought I'd get the ball rolling.

73 de Jim VK4GFT/N9GFT

[senormechanico]

Your feed leg through the arch would be a capacitive drain on your antenna system, and variable in its negative effects in your RF output.

I had a 735 with a backstay fed output with only one insulator near the on our cruising Mexico boat, a LN35.

Get ready for flamers if you use this scenario, but it worked for me.
They all think anyone who grabs the backstay at the bottom is gonna get fried at certain frequencies.
I showed several HAMS and others just the opposite when I invited them to key up on whatever frequency while I stood in the cockpit holding the backstay.
They were hesitant to do it, but I insisted. Guess what? NOTHING HAPPENED.
It also is working for me on my current boat, a DF 1000, although with considerably less freeboard, I slosh off the chainplate with fresh water before I fire up the radio.

[Ray-Dianna]

Thank you for the early replies, so my idea of mounting the tuner under a solar panel which would put the feed wire length at 3-4 feet would be a better approach. Okay can I run the coax from radio to tuner thru one of the arch legs? Cheers to all and Happy Thanksgiving!!

[Jim Cate]

Originally Posted by senormechanico

Your feed leg through the arch would be a capacitive drain on your antenna system, and variable in its negative effects in your RF output.

I had a 735 with a backstay fed output with only one insulator near the on our cruising Mexico boat, a LN35.

Get ready for flamers if you use this scenario, but it worked for me.
They all think anyone who grabs the backstay at the bottom is gonna get fried at certain frequencies.
I showed several HAMS and others just the opposite when I invited them to key up on whatever frequency while I stood in the cockpit holding the backstay.
They were hesitant to do it, but I insisted. Guess what? NOTHING HAPPENED.
It also is working for me on my current boat, a DF 1000, although with considerably less freeboard, I slosh off the chainplate with fresh water before I fire up the radio.

Sr. Mecho, nothing at all wrong with what you are doing. We go to the next step: no insulators at all! We feed the port shroud chainplate below decks, direct from our manual tuner. There are no insulators anywhere so we are loading up all the standing rigging and the mast. Some times the mast is grounded at the base for lightning purposes. It changes the settings on the tuner, but does not seem to alter the signal radiation. Our signal is equal to or better than folks with standard issue insulated backstay antennas. We have been doing this on this boat since 2003, and before that we had a similar setup on Insatiable I, only fed at the bottom of the backstay chain plate.

No one has suffered from this practice, and we've saved a bunch of money on rigging insulators. Lots of flamers, though!

I'm always hesitant to suggest this method to others, but several of our cruising friends have switched to it, and no issues have been reported to me. So, while I say "don't try this at home" for publication, it seems a practical antenna system to me (of course, not applicable on metal or carbon hulls).

Jim

[philocat]

The 735 caught my eye. Interesting concept Jim (hi to you and Anne). Perhaps it works a little like the antenna with your namesake the "big Jim" which basically has a grounded feed point (and excellent for lightning protection). I may of commented in forum before but I had great success just with a ~1/4 wavelength copper wire draped along the inside of a plastic hull as counterpoise together with bamboo pole out the back. For anyone interested I do have the circuit diagram available in all its pretty colours.

[GILow]

Of course it is worth mentioning that Jim and Ann have constant halos of St Elmo's fire radiating from their hair and that Ann cooks dinner by putting an induction pan on her head at sunset. But other than that, no problems with the radio rig.

[Seeking Solace]

For what it's worth the voltage is usually only high on the ends of antennas and usually more so on the lower bands. RF is only a real issue to consider when you're near 30Mhz. That's where you're most likely to absorb it according to all the documentation I've read over the years. That's not to say that if you weren't using microwave bands that you wouldn't cook yourself.

Holding the antenna while transmitting isn't a very smart choice regardless of the possibility of being shocked or exposed to RF. It detunes the transmit antenna and sometimes a great amount. Although if you're using voice (Phone) it's likely the duty cycle isn't enough to damage anything unless you're long winded.

When I got my license RF safety was barely mentioned on the exams. Now it's a big deal and is all over the exams. The only time I ever got shocked transmitting was when I reached to tighten a connector and wasn't smart enough to unkey first.

Jim, what kind of issues do you have with your manual tuner while under way? Does it get jarred off of it's settings, or is it tight enough that it will stay put even in rough seas? What model are you using? I've got 3 different antenna tuners and only my least favorite the ATA-300 stays put. It's huge though and I absolutely hate using it. I much prefer my compact MFJ tuner, but it's easy to knock the air capacitors out of adjustment in rough conditions. It was and is still a fraction of the cost of a automatic tuner and my guess is more accurate to fine tune.

[Jim Cate]

Jim, what kind of issues do you have with your manual tuner while under way? Does it get jarred off of it's settings, or is it tight enough that it will stay put even in rough seas? What model are you using? I've got 3 different antenna tuners and only my least favorite the ATA-300 stays put. It's huge though and I absolutely hate using it. I much prefer my compact MFJ tuner, but it's easy to knock the air capacitors out of adjustment in rough conditions. It was and is still a fraction of the cost of a automatic tuner and my guess is more accurate to fine tune.

G'Day SS,

I'm using an MFJ Versa-tuner II that I bought in 1986 when we first set out cruising. I have never had any issues whatsoever with the settings changing under way... plenty of friction in the through-panel bushings and the variable capacitors, I guess.

It is certainly more trouble to deal with than an auto tuner, but likely does a better job matching. And when we were dismasted in our previous boat, I simply laid a random bit of wire across the deck and it tuned it up on 40 meters, well enough that I could report in on our morning cruiser net and inform folks of what had happened. And then spent hours convincing them that we did not need or want to be "rescued"... hams and cruisers both have an unquenchable urge to help out!

Jim

[Seeking Solace]

Thanks for the Reply Jim. I've got a MFJ Deluxe Versa Tuner II and I think it's rated to 300 watts. It's model #949E. I bought it used, but was pleasantly surprised that it was in new condition when it came in the mail. It's been my main workhorse and it's never arked over. I only run 100W max on that antenna system. It's by far my favorite and tunes easily using the chart I keep pinned up behind it.

I've also got a Vectronics and the AEA tuners, but they aren't nearly as smooth or responsive.

Ray, You've got a pretty good radio there. I've repaired a great number of them and they survived lightning strikes, power surges, and very high SWR scenarios with very little problems. I might give you one small piece of advice concerning it. There is a back story to it, so here goes.

I had a fellow a few blocks over bring me his 735 with all of the front panel lights out on it. I offered to replace them with LED's, but he wanted it to be exactly like Icom designed it so we ordered the lamps from Icom. He'd bought a new rig from Ten Tec , I believe an Eagle and it had a matching power supply. After a few weeks he called to complain that the lights were dimming in the unit on transmit and it had not previously done that. He brought the radio back to me and I could not reproduce the issue. Once home his problem began to manifest again. After a long discussion about what the cause was it came to light he was using the small switching supply that came with the Ten Tec on the Icom radio. The newer supply wasn't able to handle the power requirements as well as the old analog supply. I'm not sure if that also was apparent on his transmitted signal (He's a 100% CW operator). After going back to his old power supply the problem was a non issue. Long story short, use a quality supply with it. Otherwise you might consider replacing the lamps with low power consuming LED's as they fail.

No personal experience with the AH-2, but I've heard they are pretty reliable. If it were my vessel, I'd likely do exactly what Jim did with his. I'd just ask people to not handle the rigging while transmitting. I've talked to people using the flashing on their house running under 4 watts. The joked that the down spout gave them a vertical and the rest of the gutter was a horizontal. Maybe they're right? If you decide to do the backstay method, I'd love to see installation pictures.