Category Archives: Repair

Here’s what $2.89 will buy…

If your’e going to own a Beofeng radio, you might as well have a cheap knockoff microphone to go with it. So, off to eBay we go.

And, surprisingly, for a Chinese purchase, it arrives in about 2 weeks.

This microphone cost $2.89 with free shipping.
After all, what else do you need, but an electret capsule, a tactile button and some plastic.

Works perfectly. It’s light – there’s nothing to it but the essentials. I have no idea if the Beofeng logo is ‘official’ or pirate. Cost: $2.89, free shipping.

This is great. Now I’d like another one to hack up, for other little radios I’ve built. My second order was placed during Chinese New Year, and it takes an additional week to arrive.

This one doesn’t work – no audio. And it has a small rattle inside. Well, whaddaya expect for $2.89? Out with a T9 Torx screwdriver. Turns out the electret capsule is soldered, but… somehow there’s no connection. Fixed it by soldering from the electret capsule to another exposed point.

But look at the PCB: the solder-mask is bubbly. It’s just poor quality. Heck, I don’t know how they can provide the plastic shell, the wire in the cable, the dual plug, the electret capsule, a tiny right-angle tactile button, and the screws — for $2.89, shipped.

Repairing VTVM Pilot Light

Lurid Red of the new Pilot Lamp
Lurid Red of the New Pilot Lamp

I found a great solution to old tape used in the Heathkit VTVMs for the RED pilot lamp. The lamp is just a #47 bulb, shining through a hole in the top of the meter face. The tape isn’t mentioned in the instructions, so perhaps it was pre-installed in the back of the meter face.

 

 

A Cheap Fix
Also Useful for Repairing Antique Pilot Lamp Film

 

In any case, this tape sometimes falls off or is nearly falling off after 50 years. It also fades and loses it’s reddish glow. An excellent solution was found in the form of a red-neck repair from the auto parts aisle of Walmart: Tail Light Repair Tape, US$2.00.

Tape replaces old, crinkly, peeling tape from this spot.

 

 

 

Above: Below the roll of red, translucent tape, the old pilot lamp film and the new piece cut to replace it.

Left: Adhesive is sticky and the new piece goes over the hole in the meter through which the pilot lamp shines.

Cosmic Stink

Last night, I turned on the Hallicrafters S-120 to catch some C&W music on AM.

Zortch! Followed by (smolder). And a great and unholy stench was unleashed.

It seems I’d left the old selenium rectifier in-circuit. Big mistake. I’d discounted the many comments by “The Elders” on Antiqueradios.com regarding the failure mode of these old rectifiers. Never again. After using it for several months in the office, then occasionally at home, I can now say this: it may have been sitting in storage for 30 years, mean-time-to-failure (MTTF) is about a year.

And if you don’t know what burnt selenium rectifier smells like… you don’t want to.

Replaced the old selenium rectifier (which made a satisfactory ‘clunk’ in trash can) with a 1N4007 diode. Also replaced R21, a 33 ohm Fuse-Resistor which… had done it’s job by going not quite open, but to over 100k-ohms, with a 5 watt, 100 ohm resistor. This value put the DC input voltages at almost the exact levels indicated on the schematic.

Now I’m on a hard-target search for any remaining selenium rectifiers in any of my test gear or tube radios.

TrueTone Portable

I took a part of my day off to do a quick redo of <a href=”http://mikeyancey.com/TrueTone_refurb.php”>a TrueTone Portable</a>. Many thanks to <a href=”http://mikestute.com” target=”_blank”>Mike Stute</a> for giving me this one a couple of years ago, when I casually mentioned that my mom had had one of these.

Zenith Transoceanic – Y-600

Finished the <a href=”TO-Y-600_refurb.php”>TransOceanic Y-600</a>. This is a magnificent radio and turned out nicer than I could’ve expected. A fortunate turn on this model was that the 1L6 tube is in good shape. Although in fairly ready supply, the tube has reached ‘unobtainium’ prices, even though solid-state substitutes are available. In any case the 50A1 was replaced with a solid-state replacement, which provides very stable current and voltage regulation, which is a good thing given the expense of the 1L6 tube.

Hallicrafters S-38B

Finished the <a href=”http://mikeyancey.com/S-38B_refurb.php”>Hallicrafters S-38B</a>; it’s seen some daily use in my office at work. This is my first run-in with the AC-DC power issue and I found a way to route the power cord ‘HOT’ through the switch to eliminate (unless the house wiring at the socket is reversed) shocks from a faulty cabinet insulator.