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Need techie help on a RCI 2970, older model

ExitThirteen

Grumpy and Cranky
Apr 18, 2008
1,968
1,691
173
Cornpatch of Iowa
Heya all! I recently purchased a used 2970 for a good price off Ebay, but it has 2 problems, one is fairly minor, the other one is pretty major.

The major problem:
LSB is exactly 2.5 kc high off frequency. I have checked the frequency off of each oscillator can, the AM and USB cans are right on at 10.6950 (AM) and 10.6925 (USB). The LSB dials up at 10.7000 (+2.5kc high) I'm unable to do a full alignment on this radio, as I don't have all the equipment yet, but what I can tell you is that the clarifier IS locked, and in TX/RX, the AM/FM/USB are just fine, LSB is off 2.5kc. The LSB also sounds a bit distorted as well, which could be tied in somehow with the LSB being off frequency.

The minor problem: The clarifier knob is not linear when tuning, the potentiometer checked good on a multimeter for linearity and for resistance value, so that eliminates the clarifier pot itself being bad. It is linear about 3/4 turn, then "jumps". It does the same thing when the clarifier is either locked or unlocked.

Methinks someone had too many screwdrivers in the thing, I'd like to either be able to fix it myself, or send it to a reputable shop that could (hopefully) fix it without sending it back and saying, "It's junk." LOL

Any information would be most helpful, if you have questions, I can try to answer the best I can. Thanks in advance. Cheers!

-Rick
 

you said you checked the frequency in each mode which means that you have all that you need to fix your problem. (if i am thinking correctly LOL)

you should be putting the positive probe of your freq. counter to the cathode of D45, and the negative to some point that is connected to the ground trace on the PCB.

AM is L27. Key the transmitter and adjust for 10.6950 mhz. (mic gain should be all the way down for these adjustments)

USB is L29. Key the transmitter and adjust for 10.6925mhz.

sounds to me like these two are already ok, its just the LSB can that needs adjusting so:

LSB is L28. Key the transmitter and adjust for 10.6975mhz.


make sure you use a plastic or wooden tuning tool for these adjustments.
you can make your own, just make sure it fits snug in the slug so you dont break it.

there are more adjustments you can do if you have the freq. counter, but i'll leave that to you.
if you dont already have it, here is some good info on that chassis:
http://www.cbtricks.com/radios/rci/rci_2970/index.htm

good luck,
LC
 
I think this one needs to go into the junk bin... LOL

I'll most likely strip it out, unless someone wants to give me something for it, since the 100W board on it is fine, same with finals, etc..


Anyhow, thanks for the posts, but it's a dead duck, methinks. :thumbdown:
 
exit13,

please explain to me why you think it is a dead duck.:confused:

you might only have to turn one tuning slug to fix it.

is there something else wrong with the radio other than just being off freq. in one mode?

if that is all that is wrong with it, it could be one of the fastest CB repairs in history. (excluding the ones where the tech just turns the squelch down and the RF gain up.LOL)

so, whats up?
LC
 
Well, barring the oscilloscope part (mine's down) I can do a full alignment on the radio, but nothing really wants to line up, frequencies jump around, I can't get voltages stable. I replaced both of the 10.240 Xtals with new ones, but the frequencies still bounce pretty bad, and to be honest, I'm not knowledgeable enough to troubleshoot the harder problems. If I found a shop or someone reputable to have a look at it, that's fine, I'd pay a modest fee to have it looked at, but I highly suspect there's a bigger problem than what the LSB problem might indicate. I really don't feel like putting anymore time into it, as I've put a lot into it already.

Just my 2 cents in it. :p


(edit) Seems like the deeper I go into fixing/aligning it, the more problems I see, that's why I made the comment about it being a dead duck.
 
Last edited:
gotcha.

i would say, if you try aligning the VCO, and it is stable, then you have voltage regulator issues or something like that.
maybe try aligning the VCO and see if that doesnt "stabilify" things a bit.

if you are just done with it, and want it fixed; send it to DTB radio, who was the first one who replied to this post.

he has been around forever and a day, is very reputable, and is good enough to find the problem without telling you its "junk".
unless of course, it is.LOL

seriously, he's got a lot of satisfied customers on this board.
just ask around.

here is a link to his site:

http://www.dtbradio.com/

good luck,
LC
 
Thanks for the heads-up Loosecannon, I might have DTB take a look at it. If it's junk, it's junk, which is what I'd suspect it to be. I'll see what he can do for me. Cheers!
 

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