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Older RCI 2950 problem

blu i devil

Member
Apr 29, 2005
8
0
11
I have an older 2950, about 10-12 years old. It has an intermittent problem on transmit. I set the RF power knob so that i get about 1 1/2 to 2 watts dead key on AM. I use this to go into my 1 pill driver and then to my 4 pill box. Once in a while the dead key jumps up to 20 watts. I then just shut off the 1 pill and keep talking ( the 4 pill can handle that drive). It doesn't seem to be affected by temperature or how long the radio has been on. Any ideas??
 

i would check your patch cords this sounds stupid but ive seen weird things of different sorts caused by bad jumpers take a VOM and check for shorts in them wiggled them or move them around a bit. This sounds silly but its a good place to start
 
I'd be suspect of your meter if you see 20 out of that radio, but just to be sure, check the DC voltage coming out of the AM regulator when it jumps. Also check it when its at 2 watts key for a comparison. If the DC voltage is jumping, then its definitely a regulator issue of some kind, whether its a transistor or a POT problem.
 
Thanks for the replies. TonyV225, I'm sure it isn't the jumpers, it can happen in the middle of a key and without the vehicle moving. DTB Radio, I have a Bulldog meter that is pretty accurate. I will look into the AM regulator issue. It could be faulty components. I wish I could make it happen on the bench when needed but sometimes it goes for weeks without doing it. I don't know, maybe I'll put my Grant in the 'Burb and mess with the RCI on the bench.
 
Its hard to say with a radio that age but faulty or malfunctioning parts is most likely the suspect. I to have one sent out to Justin it would sound great for a week or so then key up and it was all distorted. Then the channels would change on there own its figured out Now I need A PART THAT CANT BE FOUND go figure they changed the parts and board set up 3 times that I know of already probaly more. And as usual Im sure you will have to change surrounding parts around the problem when you find it. Could this possibly be an issue also within the biasing section???
 
Hmmm. Consider the "scratchy" volume control, and the way the volume can jump up and down randomly on its own.

Now consider what a carrier control would do if it got "scratchy" from age, dust and oxidation.

Some control cleaner may be the whole solution. If you can observe the radio's carrier power on a 'scope, you'd see any erratic jumps in carrier as you twist the knob.

73
 

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