MT1000 TX Issues

[ve1gln]

I have 3 VHF MT1000's that all came from different places, but all three have the same problem.

The last one I just got, from a friend in the US is a known good working radio, it was shipped bare.

After I added a case, antenna, battery and knobs, I tried it out, and it has the same issues as the other two, the light blinks, VCO unlocks and it resets...Thats straight from the box, I never programmed it.

Now I just thought I had two bad radios, but after this, a new radio that I have never programmed, and is known to be working does the same thing???

I also have two UHF MT1000's and they work fine, so in doing some battery swaps and the like, just for the fun of it I stuck a UHF antenna on the new VHF radio.... solid light, no VCO unlock...

So I performed a few tests, and sure enough, the VHF's will work with a UHF antenna, but not the VHF antennas, Then new one works, but the older two don't, making me believe that i have somehow damaged the radios. The new one will TX without an antenna and with the UHF antenna, but as soon as one of the VHF antenna's touch it.... blink and reset.

And for those who will ask, yes I have taken apart the radios and confirmed the the VCO is 146-174

So I guess my question is, does the MT1000 sense SWR somehow, I mean the antenna is a single point of contact, so it's not like it can be shorted.

Awaiting your wise wisdom before I spend money on an antenna...

Thanks

Glen
VE1GLN

[N9LLO]

? 2W UHF radios and marginal batteries trying to run 5-6w vhf radios?

What is the model number on the UHF H34 or H44

chris
N9LLO

[ve1gln]

H43

Glen

[k2hz]

It is common to get a symptom like that with loose or corroded battery contacts on the radio. The voltage drops so that the radio resets under high current on TX or sometimes even on full volume RX.

Be sure the battery contact screws on the bottom of the radio are tight and the contacts are not corroded. If that is not it, it is possible there is a bad connector, flex or ground connection in the radio.

I suspect that the PA current is reduced with a mismatched antenna and that is why the problem seems to go away.

[WA3VJB]

There's a chronic failure mode in the MT1000/HT600/P200 line between the motherboard and the antenna mount, involving a stiff piece of wire off the bottom of the threaded mount that flexes and breaks. It can be intermittent, which is the damndest thing, where the wire's just touching sometimes, or touches enough for receive but not transmit (the junction won't take power).

Two ways of getting to it: easy and hard.

Easy: with a needle-type soldering iron poke down the hole and dress up the solder pad and wire junction on the motherboard.

Hard: disassemble it all and really dress it up right.

For casual or gentle service the easy method is probably reliable. NO more swinging the radio around by the antenna to make a point anymore, okay ?

[ve1gln]

Actually I figured it out recently.

Bad Battery!!!

Works good now.

Thanks all

Glen
VE1GLN