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Uniden Washington

silverstreak

Active Member
Jul 23, 2006
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Radio is all stock but has the normal clarifier mod done.no extra channels.The radio is one channel off.Your on 19 your really on 18 and so on.Tried to do a alignment and cant even get it close to normal channel.Anybody run into this before?And the only other thing wrong is the channel display some segments are out any help would be great the radio looks new.
 

Have you just got this radio recently?
If so, I'd have a look at this area:

More Slide?? Install a 5.6uH choke on the banded end (grounded end) of the varactor diode D37 or replace D37 with a super diode.

I had a Grant that had a super diode and choke added, and it was one channel off as you describe, I can't remember if the crystal frequency was changed also..

A "super diode" may appear to be factory, but the one I found looked odd.
 
Last edited:
Ah? Ok, Hey! - then if you are still "off" by one channel - the Clarifier mod you did - skipped a step.

The output wire? Where does it go, from the Pot to the board - to bypass the RX/TX "feeder" issue?

Because if you get power from the MB3756, and yet feed the Clarifier - does the RX frequency Track the TX frequency?

If not, look for R187...R187Washington.jpg

Remove it completely and APPLY (as in solder it) it ACROSS the Clarifier Source (from MB3756 chip) to Wiper (adjustable output)...

Ok, with that done...did you BYPASS the little board the Clarifier used? Then you're missing R415 - it needs to be from RETURN of the Clarifier to ground - so go back and make sure R415 is in the return side of the Clarifier pot it pushed the varactor tuning voltage up to bring it to center slot. just reroute your Clarifier return back to that CB/PA switchboard where R415 is - you'll be fine.

PA365g BoardTuningCenterning.jpg
 
I didnt do the clarifier mod so I will have to look to see what they did.Its the newer model 5 pin 8719 pll thanks to all that has replied
 
If all you want is to make the clarifier follow your receive frequency when you transmit, it's fairly simple. Makes the radio a lot easier to use on sideband, when everyone can line up his transmit frequency with everybody else. It amounts to pulling one end of a diode, one end of a resistor, and one end of a wire. The end of the wire that gets pulled out gets soldered to the 8-Volt supply that feeds the PLL chip.

I have a more-detailed version at work on the air-gapped computer. I can dig it out next time I'm there if you're interested.

This radio is not a good one for 'stretching' the clarifier to tune a wider range of adjustment. If you do that, it makes the clarifier control touchy, and hard to tune a sideband signal just right.

73
 
First thanks for the reply.I have been working alot so I havnt had time to look at the radio.Today I looked at it and it looks like they ran one wire to 8v and the other to ground.They didnt remove the resistor or diode.so either I will finish it or put it back to stock and see if its still one channel off.
 
This radio is not a good one for 'stretching' the clarifier to tune a wider range of adjustment. If you do that, it makes the clarifier control touchy, and hard to tune a sideband signal just right.

73

Washington Clarifier.jpg
8719 Washington Clarifier (single conversion chassis)

- vs -

148 Clarifier.jpg
8719 148 Clarifier (double conversion chassis)

There is an additional varactor diode circuit going to the emitter of the oscillator, this causes the double conversion 8719 chassis (148/2000/Grant/Madison) to have a wider range than the older single conversion 8719 chassis radios (140/142/Washington).
 
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Check pins16 and 17 on pll make sure no shorts or cut traces these 2 pins will give a 10kc jump in radio. Look to see if there are any wires connected to the 2 pins if so follow them and see if they go to the front of radio. Someone might of added a 10 kc jump switch.
 
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