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rci 2990 low modulation
- Thread starter cbkidd1
- Start date
hi fl native. Yes i just got the radio. Well lets say it will be here next week. The guy that sold it to me said that it transmits and receives fine. But has low modulation. He is telling me that he sent it to ranger to be checked. And they said it needs a new cpu board. Would the cpu board have anything to do with the modulation? I was thinking maybe the mic or mod vr or audio chip? But i am no expert. :?
well if ranger said it. thats what it is. hope you didnt pay to much for it.
but there are some real good techs on here you can send it too.
DTB radio
and
8541 electronics
im sure one of them will chime in here and help you out.
but there are some real good techs on here you can send it too.
DTB radio
and
8541 electronics
im sure one of them will chime in here and help you out.
It don't sound to good lol. I payed 200.00 for the radio. dtb radio is not to far from me. I live near waynesboro pa. He is in carlisle pa. I sure hope it can be repaired. I hear that the cpu boards for the 2990's are very hard to find. thank you for your input. Have a nice weekend. 
I don't like ot disagree with RCI, but I can't think of anything in the UPc board that would cause low modulation. The upc simply controls the various functions, and monitors others, it doesn't come into play as far as amplifying the mic audio. The only off-chance possibility I can think of is somehow the cpu is floating between AM and FM modes, and partially shutting down AM modulation, but thats such a long shot that I'd bet big money against it.
im no expert either but on am mode the 2990 is a low level
modulation radio.id hook it up to a meter perferbly one with
a modulation meter and see how its doing.ive owned 2 of them
and with a n/c mike or stock mike 70-90 percent saudio is about the best they done.but one the recieving end everyone
says it sounds good and very clean.but ive also found my connex 3300hp has more audio then it but no ssb
modulation radio.id hook it up to a meter perferbly one with
a modulation meter and see how its doing.ive owned 2 of them
and with a n/c mike or stock mike 70-90 percent saudio is about the best they done.but one the recieving end everyone
says it sounds good and very clean.but ive also found my connex 3300hp has more audio then it but no ssb
Thank you guys for your help. i don't have the radio here right now. It will be here sometime next week by ups. I will hook it up and let you know whats going on with it. dtb your not to far from me. could i bring the radio to you ? And have it fixed the same day if it's something minor? Or should i ship it two you. Thank all of you again for your time and help.
That is not the CPU causing that the CPU is basically the brain that makes all the digital functions of the radio work the audio is basically run seperate unless its a fancy digital proccessor like the Kenwood in my wifes car which its not her audio is hi or low on hers and its done by the push of a button after finding the right adjustment in a digital menu.
That 2990 audio is udjusted by Variable resistors (VR's) Im willing to bet that is out of adjustment or theres a bad resitor ETC just have it tuned by DTB or someone that is reliable. If that CPU was bad it wouldnt do anything you would have one hell of a paperweight.
That 2990 audio is udjusted by Variable resistors (VR's) Im willing to bet that is out of adjustment or theres a bad resitor ETC just have it tuned by DTB or someone that is reliable. If that CPU was bad it wouldnt do anything you would have one hell of a paperweight.
I don't know about a 2990 being a "low level" modulation type radio? Whatever the heck that means. When properly tuned they rock, with a D104 desk mic they BOOM on the airwaves.
I was thinking myself. That the cpu did not have anything to do with the modulation. But i wanted to be sure by asking people on the forum what they thought. I sure don't need a paperweight. lol. Going to see if dtb can look at it. I don't live to far from him about 50 miles. Maybe i can have it fixed wile i wait. Thank's for your input tony.
hotrod said:
That is absolutely incorrect. The 2990 uses high-level modulation, injected directly into the collector of both the driver and the finals. The modulation output is from a heavy-duty, DC-coupled PNP power transistor circuit where one transistor directly drives the main output transistor. If your units never did more than 70-90 percent, then they were never tuned completely.
manual says
am modulation=classb amplitude,colloctor modulation
ssb generation=dual-balanced modulation
whatever all this means but i honestly thought they were a
low level type modulation radio.thought thats why so many
people liked these radios on ssb.and i was wrong on the
audio percent i was getting. it was 90-100 percent audio
and that was with a asatic 636.not bad at all id say.
am modulation=classb amplitude,colloctor modulation
ssb generation=dual-balanced modulation
whatever all this means but i honestly thought they were a
low level type modulation radio.thought thats why so many
people liked these radios on ssb.and i was wrong on the
audio percent i was getting. it was 90-100 percent audio
and that was with a asatic 636.not bad at all id say.