[Kenwood] TM-641A No Transmit on Repeaters.

[Ken Brown]

Hi Gary,

What test equipment is available to you? Can you confirm that the 
transmitter is really putting out several watts of RF power? A handheld 
at arms length may confirm that it is on frequency and modulating, but 
it says very little about how much RF is being generated. The dimming of 
the display lights is probably an indication that it is drawing 
appreciable current during transmit, but no proof that it is really 
generating much RF. Can you measure the current draw, and confirm that 
the supply voltage is staying up high enough when you key it? (I don't 
know what high enough is for that rig, but if it stays at 12 VDC or 
higher I would guess that is good enough) You say that the PLs are 
correct, however in many radios setting the PL tone frequency does not 
necessarily turn it on for transmit. You need to confirm that too. By 
the way, the handheld should receive it even if the transmit PL is 
turned on. I don't understand you having to turn it off to get the 
handheld to receive it. Maybe I'm confused about whether the handheld is 
receiving or the 641 is receiving. Do you hear repeaters? Just cannot 
get into them?

If the lights are dimming, but no significant RF power is coming out the 
antenna port, I would be very careful and transmit only briefly. Maybe a 
failure in the path from RF power amp to antenna port. Failed switching 
diodes perhaps. Or does it use a T/R relay?

DE N6KB



On 12/6/2014 12:08 PM, Gary V. Smith wrote:
> I recently picked up a TM-641A from an estate sale. It has just 2m and 
> 1.25m installed.  The 220 side seems to work good on simplex although 
> there is a dearth of 220 repeaters in my area on which to test it. The 
> display light dims considerably on transmit but that may be an antenna 
> issue. It also transmits on any 2m simplex frequency.  At first I 
> didn't think it was doing that when I happened to notice that one of 
> the simplex frequencies had a PL on it.  When I removed that a hand 
> held at arms length received it fine.  I tested on other simplex 
> frequencies and it worked fine.  However, it will not transmit on any 
> repeater set up even though it presents as doing so.  I tried several 
> different local repeaters.  All offsets and PLs are correct.  No joy. 
> Thinking it might be a PL issue I programmed a local repeater that 
> doesn't currently have a PL.  Still no joy.  Any thoughts on what this 
> problem might be?
>
> 73,
> Gary - W6GVS
> Dowagiac, MI
>
>
> _