RCI-2950 FL3 10.695 Mhz Crystal

[KD2GOE]

What are the symptoms of a bad side band filter? FL3 10.695 Mhz Crystal the Main PCB is a EPT295013Z

this radio has had an alignment..

What's going on is if I tap on it I can here a ping through the speaker all most like when you tap on a vacuum tube in a guitar amp.. that don't sound normal to me, and is there a tighter filter I can install to help side band?

It is harder to Clarify people in compared to my uniden Washington and Cobra 148GTL.. BUT people say I sound fine and there is no drift... it is hard to describe but people don't sound are pure and clean..

There is 7 S-units of static all the time.. unless I turn down L16 witch is the SSB sensitivity. I have it set to a balance to where I have grate sensitivity and low static.

 

[M0GVZ]

this radio has had an alignment..

Well all bets are off then. Might be an idea to find a proper workshop and get them to undo what has been done and return it to spec.

There is 7 S-units of static all the time.. unless I turn down L16 witch is the SSB sensitivity.

Not according to the alignment procedures from Ranger...

Alignment procedure for 2950DX

Alignment procedure for non-DX versions.

Notice the equipment required.

DC Power Supply ( 13.8 Vdc, 20A )
• Oscilloscope (50 MHz), with X10 probe
• 50 W dummy load
• Frequency Counter - 0 to 30 MHz
• Digital voltmeter or Multimeter.
• Audio Generator
• FM Signal Generator
• SINAD Meter
• RF Wattmetter ( 25~60 MHz, 100W )

If you don't have those you shouldn't be altering anything.

I suggest that before you continue to screwdriver it into a useless lump of metal you find someone who has the right equipment and knows what they're doing.

 

[Captain Kilowatt]

If you cannot tune in an SSB signal precisely regardless of how much you try it sounds like the signal is not centered in the filter's passband. I doubt the filter is bad but it does sound like it needs a proper alignment regardless of who did it before or how long ago it was done.

 

[KD2GOE]

Well all bets are off then. Might be an idea to find a proper workshop and get them to undo what has been done and return it to spec.



Not according to the alignment procedures from Ranger...

Alignment procedure for 2950DX

Alignment procedure for non-DX versions.

Notice the equipment required.

DC Power Supply ( 13.8 Vdc, 20A )
• Oscilloscope (50 MHz), with X10 probe
• 50 W dummy load
• Frequency Counter - 0 to 30 MHz
• Digital voltmeter or Multimeter.
• Audio Generator
• FM Signal Generator
• SINAD Meter
• RF Wattmetter ( 25~60 MHz, 100W )

If you don't have those you shouldn't be altering anything.

I suggest that before you continue to screwdriver it into a useless lump of metal you find someone who has the right equipment and knows what they're doing.

thanks for the replay but...

Yes thanks I have 90% of the tools you listed.. I did take this to a shop I told them just do a alignment... I am trying to understand what is going on with this radio posts like this are not helping me understand why the radio is not working right. I have narrowed it down to may be a crystal problem.

It works grate on AM/FM and TXing grate on side band just not receiving on side band the single is grate just has a little talking through a fan sound...

At some point I want to be able to do this all myself I have been reading books and book on radio repair so just taking it to a shop is not helping me..


So back to my main question What are the symptoms of a bad side band filter? FL3 10.695 Mhz Crystal..

 

[KD2GOE]

If you cannot tune in an SSB signal precisely regardless of how much you try it sounds like the signal is not centered in the filter's passband. I doubt the filter is bad but it does sound like it needs a proper alignment regardless of who did it before or how long ago it was done.

Thanks MR. Kilowatt That sounds about right I can get people in but they always just seem to be off a little. and i'll look into that direction..

I was thinking the filter was letting to much bandwidth through and overwhelming the receive...

As a note I am not touching any other adjustments I am just probing around on it.


if it comes up I did touchup every solder joint on the radio with 60/40 solder

 

[M0GVZ]

At some point I want to be able to do this all myself I have been reading books and book on radio repair so just taking it to a shop is not helping me..

Whilst I fully support what you're wanting to do I think I'd be learning on simpler and cheaper sets. Start off with 40Ch AM sets, maybe get a junker from Ebay and get it going again and then move up gradually.

Learning to walk before running as it were.

Radio, both amateur and CB, are in dire need of decent repair shops and not just another screwdriver jockey so take your time to get a good understanding and give the hobby what it needs. Start with concentrating on realigning to spec and getting that right 100% of the time before then starting to "blueprint" tuneup radios.

 

[KD2GOE]

Whilst I fully support what you're wanting to do I think I'd be learning on simpler and cheaper sets. Start off with 40Ch AM sets, maybe get a junker from Ebay and get it going again and then move up gradually.

Learning to walk before running as it were.

Radio, both amateur and CB, are in dire need of decent repair shops and not just another screwdriver jockey so take your time to get a good understanding and give the hobby what it needs. Start with concentrating on realigning to spec and getting that right 100% of the time before then starting to "blueprint" tuneup radios.

Thanks for the support. I have so far fixed 2 142gtl sofar .
I am not for cutting or clipping radios as I feal they put all the R&D in to making them unless it is for unlocking a Clarifier.

 

[Onelasttime]

I have had a SSB mechanical filter go bad on a 2950 and it kept drifting off freq. So the radio went from being the most stable SSB radio ever to drift city. I also found that my voltage regulator was bad as well and was allowing for some wild voltage fluctuations which is also not good for stability barring all the other stuff it can damage. The radio was about 3-4 years old at the time this happened. I used every night after school and work.

You can either have a custom filter made by using off the shelf crystals and caps kind of like how Uniden does for their older cb radio that did not use a shielded metal can. You can look for vintage SSB filters in that freq. that have more poles and tighter band width then show horn it in on a piece of bread board. You can replace it with an OEM part than use additional single crystals in the 1st and 2nd parts of the IF chain. You could build something like the old Channel Guard tha CBC used to sell. I have not had to work on a 2950DX so I have no clue how hard it is to use discrete parts on SMD board in that area.

Do it use two crystal? Usually you will have two one 455Mhz and the other one will be something like 10.695 or 7.8Mhz on non-ham radio so CB's and Exports and such. When you get into ham radio's the 455 is still fairly common but you also start seeing all kinds of odd stuff like 8.832Mhz, 500Mhz, 10.7Mhz, 23.674Mhz and you start to see one crystal for USB, one for LSB and a Sym one for AM sometimes specific crystals for FM and CW etc....That is not even counting optional narrow filters that a radio might have that are user selectable. It is mission impossible to find a 15 pole 2.4Mhz wide 10.695Mhz Center Freq. mechanical filter. I can find them all day long for 455Mhz because those are used in high end Ham gear but 10.695 and 7.8Mhz are basically for (CB Trash Talking) radio's and that is the problem. I have been looking for something like that for 10.695 and 7.8 for a while. The best I can find are 4 pole units and they always have some insaely wide band width like 16-18- or 20Mhz wide.

For the record anyone wondering why today's radios(cb and export) are so noisy it is the tiny cheapo wide bandwidth filters being used. If they get any smaller or wider we might be able to hear 12m and 6m on CB.

Look up channel guard you can make something like it on bread board no problem! I would still put an OEM filter back in. Some crystal filters have a capacitor built in that you can not see some do not. Some have matching transformers some do not. You want to make sure the impedance is right for the circuit as well. You do get some signal loss when inserting more filters into the circuit and some people like to add a higher s/n transistors to the mix. You normally will insert into a cap feeding into out out of the OEM filter. Just know you can not just lose the cap it has to go back into the circuit in the same relative position to the chain before or after the additional filtering you installed.

I know this is not a new thread. I am getting ready to do this one some radio's though and have been shopping for parts. So I found this thread while looking for parts and thought I would toss this in and see what comes up.