Can anyone tell me what the difference is between the old Icom 731 and the Icom 735.  Externally, they look identical....every detail of the buttons and case is identical.  The 731 came out around 1 to 2 years before the 735.  I'm wondering if Icom just rebadged it as a 735 or if there was any actual improvements.  I've not been able to find any specs or manuals on the 731 so I was wondering if anyone knew off hand.

Thanks.

I just got an old Icom 2400a dual band from an estate sale today.  I paid $50 for it.  

Problem is, everything works on it except transmit and receive in both the 2m and 70cm bands.  

I've already check for the basics like internal fuses, didn't see any obviously burned parts, when I turn down the squelch I get static through the speaker, used my HT to transmit to it and got nothing, checked its output with a frequency counter and nada.  I've checked the user manual and everything is configured correctly.

I'm just wondering if anyone has any prior experience with this radio before I mail it off to an Icom
Service Center.

I should clarify a bit, the radio was left on for 2 hours prior to the testing.  So it had warmed sufficiently.

The radio was jumping wildly up and down in frequency at random intervals.  So I sent it to the Icom Service Center in Washington.  

They replaced the trimmer capacitor I mentioned.  It was a known problem to them.

I'm a little upset that the radio came back to me with the marker switch still on and the radio more than 500 Hz off frequency.  

My ham club pulled out their test equipment and verified it.  So we adjusted the cap using a scope and got it down to +-100 Hz, which is within tolerance.  As you let the radio warm, it got better.  

So I sent a letter to Icom.  The service manager wrote back and told me the tech that worked on my radio had 20 years experience with the 735 and he could not understand why it was so far off.

I've been flipping through the FCC rules, but haven't been able to find what I'm looking for and I can't remember the rule exactly myself, so I was wondering if someone knew the answer.

A friend of mine has his technician's ticket.  Is it legal for him to operate my station in the HF General class SSB bands if I am next to him as the control operator?  

And if it is legal, how do we I.D.?  For example, is it his callsign slash my callsign or the reverse?

He's never operated HF before, so I thought I'd introduce him to it as an incentive to upgrade.

Thanks,
Paul.
Apache Junction, AZ

Yes, you are correct, it is a fan dipole.  Hmm, maybe to get the wires as far apart as possible, I can keep the 40-meter as the horizontal dipole and turn the 20-meter into an inverted-V.  I'll have to explore that more on the three-day weekend next week.

Thanks for the advise.  I'll post the results.

I'm thinking about the inverted V option.

My neighbor had some old fence poles, so we erected them this morning and brought the low end up to match the other end (both ends are now 20 feet above ground level).  No change in SWR for 20- and 40-meters at 4:1 constant from band edge to edge, but the tuner is having a slightly better time tuning 40-meters to about 1.3:1.

Yeah I kinda thought that the slope was the problem.  I wish I could raise the low end, but its just not possible.  I may be stuck with the manual antenna tuner, but I was hoping to find a way to tune it and discard the tuner.

Its not on their website, but Ham Radio Outlet has stacks of RadioWavz products that are not on the RadioWavz website.

I'm feeding it with coax which is how this antenna was designed to be fed (SO-239 on the balun).

After 10 years of being inactive, I'm getting back on the air.  Just got my rig back from Icom with some repairs and its working good as new...Icom 735.

All my old antennas are gone expect for an old 10-meter dipole.  It works perfect and tunes at about 1.1:1 running diagonally across the inside of my car garage.

Anxious to get back on the air, I purchased a RadioWavz 20/40 meter combined dipole.  Two 1/2 wave dipoles fed from the same balun.  

To make it fit in my lot, it runs from the top of the RV garage (about 20 ft high) and slopes down to the back fence (about 7 feet high).  An inverted V is not an option as the legs would end up right in the middle of the driveway on both sides of the garage.

I'm feeding it with the same cable that fed the 10-meter dipole....just to be clear, the 10-meter dipole is no longer fed.

I'm getting an SWR of 4:1 or greater on both 20- and 40-meters.  Same SWR at the bottom of the band, middle and top.  So I'm not sure if I need to lengthen or shorten it.  There are no metal objects, structures (other than the peak of the garage separated by the end insulator) or trees nearby....only barren desert beneath and around it (I'm outside Phoenix, Arizona).

I've double checked the coax and it is in perfect working order (applied a 12 volt source to the center and braid and checked with volt meter at the other end).   I've also checked all the connections at the antenna by connecting a 12 volt source and checking everything with a volt meter.  I also checked from the ends of the wires back to the balun...perfect..no breaks.  All perfect.

My manual antenna tuner (MFJ-945D) will tune 20-meters down to 1.1:1, but it has significant trouble keeping the SWR under 1.8:1 on 40-meters.

How should I begin trying to tune this antenna??

Thanks.

I sent my Icom 735 to Icom as the radio was 300 Hz below the display in TX and RX for all bands and modes.

The tech called me and said he was unable to replicate the problem.  Which shocks me because it was blatantly obvious.  Anyway, he decides to replace a trimmer capacitor, I think C138, which reportedly causes the frequency instability.

I got it back today.  First, I had a horrible tone every 25 Hz as I tuned the dial for the full range of the radio.  Then I realized that he left the 25 Hz Marker switch on.  So I turned it off.  Did that cause any harm??  I've never used that switch before and really don't know how to use it.

Anyways, I checked the radio against WWV today and my Yaesu FRG-100.  Now the radio was better, but still 200 Hz below the displayed frequency.....which is very noticible to my ear.  For example WWV at 10 MHz, the radio display would show 9.999.8.  

In transmit in FM at a display of 28.320 my Optoelectronics frequency counter is showing a display of 28.320.3.

Has anyone experienced this problem before or provide any advise before I call Icom to complain.

Thanks.

p.s. I'm the original owner of the radio.  Bought new in 1991.  Only used indoors, never mobile.  I've taken very good care of it.

I posted this same topic under the MARS section of the forum since they use modified radios.

I have an Icom 735 HF transceiver.  I would like to modify the radio for future MARS operations and to allow transmit on the HAM 60 meter band (which it doesn't allow now).

Numerous sources say to cut diodes D33 and D34; which I've located and would be easy to do myself.

My questions revolve around the result of doing that.  Has anyone had any problems develop from doing this?  Short term problems?  Long term problems?  TX/RX frequency stability?

Should I do this myself or have the Icom Service Center do it and check the radio afterwards?

I just want to make sure I can trust the info found on the internet as I don't want to ruin an expensive radio.

Thanks.

I have an Icom 735 HF transceiver.  I want to modify the radio allow future operations for MARS and to open up use of the HAM 60 meter band (which it doesn't allow tranmit on now).

I've found numerous articles from numerous sources about how to modify the radio.  It is pretty straight forward; just cut the leads on diodes D33 and D34.  I've located them and it would be easy to do.

My questions are:  Has anyone completed this modification?  If yes, what were your results?  

Did the radio exhibit any short term problems?  

Any long term problems?  

How was TX/RX frequency stability?  

Should I have the Icom Service Center do the mod and check the radio out at the same time or just do it myself?  

I simply just don't want to cut the leads and damage an expensive radio.  

Thanks all.

I've upgraded to General and only have enough money to build and feed three 1/2 wave dipoles.  While I'm trying to decide what bands to cut them for, I'd thought I'd ask this as a poll question.  If you were in my situation, what three bands would you construct your dipole for?

I currently have a 10m dipole for the Novice/Tech SSB sub-band.

Length is not a problem, I have enough land for 1/2 wave dipoles from the 80m through 10m bands.  However, orientation will be approximately 040 degrees / 220 degrees or more simply Northeast to Southwest.  Geographically, I'm in the Phoenix, Arizona area.

I'm primarily going to operate SSB voice.