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uniden Washington Key Up Noise

I see this a lot on the 858 chassis radios. Trc457 458 138 Washington etc. Sometimes a quick chirp sometimes a slight fart. Only the person on the other end can hear it. Never could figure out what it was. But a lot of people have said give the VCO a little turn. Never tried it.
 
We found this became a common problem in the 1990s-era Washington when the modulation limiter is opened up.

Fix is to remove a mute transistor. It serves to shut down the receiver audio when the PLL loses its lock on the channel frequency.

3KowIZ.jpg


It's marked TR45 in the late version schematic, but the screen print on the top side of the board does not have a callout for it.

73
 
I was asked to chime in on this, but i couldn't log on to the forum last night for some reason.
Looks like Nomad has it nailed anyway.

the added benefit of removing this transistor is that your receiver will no longer mute when changing channels.

you know how when you spin the channel knob a bunch of clicks like trying to go from channel 1 to channel 30 in an instant, and your receiver goes quiet until you get to channel 30?

well that won't happen anymore once you remove that transistor.
you can now spin the dial around looking for open channels without clunking through them slowly.

the equivalent transistor in a dual conversion MB8719 like the 148/2000 would be TR47.
LC
 
I remember reading something about bridging mic pins. The above info will be interesting. There was a local with a Washington couple days ago. He was trying to sell it. He claimed it was brand new and unused. Said he bought it from the widow of an old operator that died years ago, just after he bought it

I asked him if he has tested it and did it fart on keyup. He said: yeah, they all do. It's normal. I'm like: no, it isn't normal. Miffed him off. There's a local amatur hack that told him he can fix it. I'll just wait and see. It's funny how many I have heard over the years, not to mention the ones lately.

As I mentioned earlier, a friend of mine had a tech in Circleville, OH fix his fart. I just can't recall the details.
 
TR45 fixed the fart. Thank you! I was just about to let it keep farting till you posted this. Thank you again..
The popping between channels was the next issue to be looked at and TR45 took care of that also. Killed two birds with one stone.
Thank you all for your help.
 
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Loosecannon, That looks like a 23 channel Regency CR-186 mobile in your avatar. That was the first radio i played on years ago. Had it on a power supply and a 1/4 wave Radio Shack ground plane. It was also the first radio i figured out how to put channel 24 in. That was back when Red Skelton was popular. LOL
 
Loosecannon, That looks like a 23 channel Regency CR-186 mobile in your avatar. That was the first radio i played on years ago. Had it on a power supply and a 1/4 wave Radio Shack ground plane. It was also the first radio i figured out how to put channel 24 in. That was back when Red Skelton was popular. LOL

23A was taboo in my area. The local fire departments used it to conduct their fire department dispatch and chatter. Anytime we keyed up on 23A, they'd get in there all official like and try to run us off, didn't work. I took an old Radio Shack GP down about 10 years ago. We put it up in 1971. It was still working the day I swapped it out. Still had original Rat Shack RG-58.
 
We found this became a common problem in the 1990s-era Washington when the modulation limiter is opened up.

Fix is to remove a mute transistor. It serves to shut down the receiver audio when the PLL loses its lock on the channel frequency.

3KowIZ.jpg


It's marked TR45 in the late version schematic, but the screen print on the top side of the board does not have a callout for it.

73
I have same year or close radio so your saying if the modulation limiter is cut you have to remove tr45?
 
You don't have to.... it just stops the "BOOP" sound when the channel selector is changing. Maybe you like that sound and want to keep it in lol... It's up to you.
 

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