Batboard

Ok hears the deal. Good friend of mine have a nice little 45 watt vhf Cdm-1250 in his truck. It worked awesome and then it decided it didnt want to TX any more, The recieve is still very good. He said it will only TX the simplex channels. Which leads me to beileive that is not putting out enough power to reach the repeator. Ive heard of the LDMOS power amp boards going bad. Could this be the deal. He took it to the shop and they said they checked eerything and couldt find the problem. I just dont think they wanted to fool with it. They seem to be very busy. As I said it worked great so I dont think its off frequecy. I personally think is something to do with TX power. If the LDMOS went bad would it still have a little TX power?

Why don't you put a power meter on the antenna cable and measure the TX power out. This is the
only way to start trouble shooting the radio. No power out would explain the problem. Another issue
could be the antenna. If the antenna was damaged, it would show up as high reflected power by the
power meter. Last option is a bad splice or fuse connection in the heavy power wire going to the back
of the radio. There might be enough voltage to work OK in receive, but drops way low in transmit.

Jim

dbfd588 wrote:Ok hears the deal. Good friend of mine have a nice little 45 watt vhf Cdm-1250 in his truck. It worked awesome and then it decided it didnt want to TX any more, The recieve is still very good. He said it will only TX the simplex channels. Which leads me to beileive that is not putting out enough power to reach the repeator. Ive heard of the LDMOS power amp boards going bad. Could this be the deal. He took it to the shop and they said they checked eerything and couldt find the problem. I just dont think they wanted to fool with it. They seem to be very busy. As I said it worked great so I dont think its off frequecy. I personally think is something to do with TX power. If the LDMOS went bad would it still have a little TX power?

ok. so if i test the power out and its very low where would I go from there

As most radio techs would say, to the repair bench.

Jim

dbfd588 wrote:ok. so if i test the power out and its very low where would I go from there