HT1250 VHF - internally generated noise across 2m ham band

[g8tzl2004]

Has anybody tried using a HT1250 on the 2m ham band?

I have a GP360 which is identical to a HT1250 but has "European" firmware. There is significant internally generated interference across the 2m band. I have tried 3 different identical radios all manufactured in different years and they all generate the same interference. There is NO problem using an external antenna. I have a HT750 (no display) and that works great with no QRM. The internally generated noise stops at about 160MHz..so from 160-175MHz the HT1250 works OK..no internally generated noise.

The 3 GP360's were all originally programmed around 166MHz..so noise was not an issue with the original users. The radios are also near mint so its definately NOT a grounding problem. I think its the LCD which is generating the noise. I have an identical UHF GP360 which works great with no QRM on UHF BUT if you place an AM VHF set near the UHF radios LCD you can hear the noise.

Any ideas. I'm thinking that all VHF HT1250/GP360's suck if you use them below 160MHz? Has anybody else found this? Maybe its a firmware issue? Maybe most VHF HT1250's are used above 160MHz so the noise is not an issue. I'm sure I once read a comment about a firmware update that caused internally generated noise to be moved...maybe into the ham band!!!!!

[MTS2000des]

how old are they? earlier (pre 2007) VHF Pro series had a problem with the antenna matching circuits on VHF models causing this exact problem, which is why I avoid them unless they have been to the depot.

[g8tzl2004]

The dates of manufacture of 2 of the HT1250's are Dec 2006 and March 2008. The other set is much earlier...around 2001.

Did the antenna matching production "fault" go on for years???

Does the Depot provide a free fix...even on old sets?

[MTS2000des]

The dates of manufacture of 2 of the HT1250's are Dec 2006 and March 2008. The other set is much earlier...around 2001.

Did the antenna matching production "fault" go on for years???

Does the Depot provide a free fix...even on old sets?

I doubt it. Free fixes? Not likely. But IIRC there was an SRN on the issue, and it involved replacing some chip capacitors and installing something else. Been a while since I've dealt with the issue.

[g8tzl2004]

If the problem is due to a design/production error then you would expect a free fix!!!!

It looks like the design error lasted 7 years, maybe more

In future I will only buy a VHF HT1250 which was made in or after 2009!!!!

My UHF HT1250's all work great.

[CircleBat]

this sounds like a filter problem within the radio or the ASFIC chip.. very common problems with these radios

CircleBat

[Garyf629]

One the way to get around the antenna match problem is to change the antenna to a MT-1000 style. Back in the day we would automaticaly replace the antenna that came with it. If you are using an orignal antenna try replacing it.

Motorola only does no charge fixes for a fixed period of time, and example would be the intermittent battery issue with these radios.

Of course you realize that these radios are not approved for use in the US, on any service.

[g8tzl2004]

I read an SRN bulletin and the antenna match problem appeared to be a TX rather than an RX issue?? The SRN was all to do with poor TX power transfer. Coverage was poor due to less TX power being radiated into the antenna...although I guess RX performance would also be down.

My problem is an RX issue due to excessive processor noise generated inside the radio and picked up by the antenna which then blocks real signals. Using a "better" antenna makes the problem worse!!! I've tried both the original tappered antenna and the older GP300 type with no real difference. I guess the only fix is to stop the internal processor noise. There is no problem when you use an external antenna as the antenna is well away from the internal noise source.

The internal noise is only a problem from 145-160MHz...above 160MHz the internal noise stops. So maybe there is a firmware fix which shifts the processor noise away from the ham band??