Kenwood TM-741A Multibander

[trace1]

Yesterday I found a Kenwood TM-741A Multibander amateur radio in a local thrift store. This one has the VHF and UHF modules and they were asking $60 for it. But since it was missing a few of the function buttons an offer of $20 was given and they took it.

I was able to get a users manual on-line (pdf) and I'm in the process of programming it now. Despite the missing function buttons everything else with this radio works great!

[fineshot1]

OMG!

Why am I never present when things like this happen!!!!!!

Awesome deal. Good luck with the new radio.

The 741 normally comes with the 2mtr and 440 band modules.

Does it have any other modules?

[trace1]

It did come with the 2 meters and 440 but no others.

[tekshogun]

Yeah, those came standard and you have the option of adding another single band; 10 meters, 6 meters, 1.25 meters, and 23 centimeters. You can cross band repeat across any two bands (which is really neat if you can work it out on 10 and 6 meters).

The problem is finding any of these modules.

[Squawk7500]

Good deal there!

I also have a TM-741A but it has poor sensitivity on the upper part of the UHF band where I would like to use the rig on the GMRS frequencies 462 and 467 MHz whenever necessary.

Yes, I have done most of the mods listed on mods.dk but nowhere do I see anything indicating how I can tune the rig to work optimally on the upper part of the UHF band where GMRS exists--if this is even possible to accomplish. Unfortunately, I can only hear very strong and nearby GMRS signals up there and can be heard infrequently as well whenever I try to call someone.

The existing mods allow RX and TX from 410-470 MHz but in my case with more sensitivity on the lower part of this band, which doesn't help me.

Can anyone suggest an easy fix for this issue, or would it require a bench-job by a technician?

Please advise, thanks.

Steve

[dwh367]

Originally Posted by Squawk7500

Good deal there!

I also have a TM-741A but it has poor sensitivity on the upper part of the UHF band where I would like to use the rig on the GMRS frequencies 462 and 467 MHz whenever necessary.

Yes, I have done most of the mods listed on mods.dk but nowhere do I see anything indicating how I can tune the rig to work optimally on the upper part of the UHF band where GMRS exists--if this is even possible to accomplish. Unfortunately, I can only hear very strong and nearby GMRS signals up there and can be heard infrequently as well whenever I try to call someone.

The existing mods allow RX and TX from 410-470 MHz but in my case with more sensitivity on the lower part of this band, which doesn't help me.

Can anyone suggest an easy fix for this issue, or would it require a bench-job by a technician?

Please advise, thanks.

Steve

That's why I use my amateur radios for amateur communications, my GMRS radios for GMRS communications, my county VHF radio for public safety communications, etc. Each radio is optimized for their intended purpose that way. The easy fix would be to get a radio that is designed for the GMRS frequencies.

[tekshogun]

Originally Posted by Squawk7500

Good deal there!

I also have a TM-741A but it has poor sensitivity on the upper part of the UHF band where I would like to use the rig on the GMRS frequencies 462 and 467 MHz whenever necessary.

Yes, I have done most of the mods listed on mods.dk but nowhere do I see anything indicating how I can tune the rig to work optimally on the upper part of the UHF band where GMRS exists--if this is even possible to accomplish. Unfortunately, I can only hear very strong and nearby GMRS signals up there and can be heard infrequently as well whenever I try to call someone.

The existing mods allow RX and TX from 410-470 MHz but in my case with more sensitivity on the lower part of this band, which doesn't help me.

Can anyone suggest an easy fix for this issue, or would it require a bench-job by a technician?

Please advise, thanks.

Steve

You should take into account that if you are using a dual band antenna, it already suffers from less performance than a single band antenna tuned for receive and transmit on a single band and in a narrow frequency range (such as 430 to 450 or 450 to 470, etc). You can install two single band (vhf/uhf) antennas and hook them up to an antenna switch (of course you lose any crossband repeater or dual watch features that may exist on this radio and you run the risk of burning it out if you forget to switch properly. You are already likely running high SWR if you transmit with this radio above 450MHz or below 438 MHz. GMRS for a mobile or base unit definitely needs a tune job whether on the radio, antenna, or both. The faint signals you are hearing on GMRS are likely exactly that, faint signals. Most users in that part of the spectrum are either very-low power HT units, the few repeaters here and there that often don't get excellent area coverage as ham radio usually does, or remnants of the old business radio service which still legally operate on these frequencies and are often low power base/HT systems for a localized site such as a hotel, mall, or theme park, etc.

If you can get your hands on a single-band UHF antenna (see if you can borrow one) and test only UHF operation. If you get better performance there you would have solved a big part of your problem. Another thing to note is that I think using this radio for GMRS use, even licensed, is illegal since it is capable of transmitting more than the maximum allowed output of 25watts on GMRS.

[Squawk7500]

Thank you, gentlemen, for your input.

Yes, I am well-aware of the general inadequacy of amateur 70cm tranceivers and antennas to properly tune in the GMRS band. The antenna I am currently using is the dual band OSJ146/440 J-Pole. Now if only there was a reliable antenna tuner available on the market to create a more satisfactory match.

I thought of purchasing the MFJ-922 UHF tuner, but as it has been reviled as a piece of junk by many--including by posters on eHam.net--I hestitate to do so. Odd that no one else has come up with a satisfactory UHF tuner.

Oddly enough, when connected to a scanner, the J-Pole definitely does pulls in all of those weak hand-held FRS/GMRS signals and from great distances, too, so I can only assume the main issue here is with the TM-471A's sensitivity.

My aim here, by the way, was simply to test the rig's boundaries and only at the low power setting of 5 watts, realizing full well the risks of potential high SWR.