Icom IC-211 PLL and Other Repairs...

 I've owned this Icom 211 for many years. I bought it from a friend back around 2008, and it's had a few issues over the last 13 years. To be fair, this is a mid-70's vintage rig, so some repairs are to be expected to a 45 year old radio :-)  

I leave this rig on 24/7, just so it's nice and stable when I get on 2m SSB. I came in the shack and realized it wouldn't transmit, and upon further inspection, I discovered it wouldn't receive, either. Oh well, off the table, and into the workshop it went. 

Once I got it on the bench, I realized the PLL wasn't locking up, so I began checking various voltages. I discovered the -9vdc supply was only about -7 volts, and by the time the -9vdc source made it to the PLL, it was only about -5.5vdc. I sub'd in a -9vdc source, and the rig fired up and ran. After a bit of poking around, I discovered a small choke that supplied 5vdc to the dc-to-dc converter that generates the -9vdc had failed and was only supplying about 3 volts to the converter. Once that was repaired, 5 vdc was supplied to the converter and it worked correctly. The 9vdc source was once again, as it should be. 

 The radio had been drifting more and more over the last year, and a quick thermal test with coolant and a heat gun revealed a small styrene capacitor in the PLL was failing, and once replace, it was solid and stable. Also, there was problems with the dial lights, and some noisy controls. 

On the bench, getting a good check-up.

I sampled the VCO to the freq counter via a .001 cap. Loading to the VCO wasn't too bad. 

This is where the 820pF styrene cap was located that caused all the drift...

This is the -9vdc dc-to-dc converter that caused the problem...

This is where I sampled the -9vdc that returned to the PLL...

While the radio was on the bench, I wanted to replace the meter lamps. I had some "warm white" LEDs to experiment with, from a string of LED Christmas lights. I discovered that 1000 ohms, 1/2 watt was about the right resistor value to bring the lamp to normal brilliance @ 20 mA or current, when powered from the 12vdc source. 

There's the Christmas lights I used. I'd break the clear part off, and the LED would slide right out. Easy to do, and you can buy a sting of these for $3-4 bucks. They're bright. You can see them in the meters of the radio, below. While the radio was on the workbench, it got a full alignment and is performing very well.