I've been in Amateur Radio since 1974, and still find new and interesting things to do. I like to build, restore, and operate on the air. This blog has been running for many years, so be sure to check out "Jump to Posts on Specific Topics" in the RH column to drill down and find lots of stuff. Visit www.WB4IUY.net, email to wb4iuy@gmail.com, or leave comments here directly on my blogs.
This is a Dentron Clipperton-L I converted to 3ea GI7B ceramic triodes. It was originally 4ea 572 tubes. Those are very expensive, and its difficult to get good 572B tubes, any more. The end result of this conversion was very nice, and GI7B tubes are plentiful and cheap.
The original filaments were 6v @ 16 a, the GI7Bs are 12v @ abt 4a total. I repurposed the 12v control power winding (good for abt 5a) in the xfmr for the new tube fils, and build a doubler for the old 6v fil winding to provide 12vdc for the controls.
Here's some vids, pics, and explanations...
Vid 1...
Vid 2...
Vid 3...
Finished conversion...
Rear panel, pre-conv...
Front panel, pre-conv...
Interior, pre-conv...
Gutting begins...
More parts coming out...
With this area gutted, I'll cut the perforated floor out to build a raised sub-chassis...
Will use this space for a lv doubler...
Filament current test... 2.7a total. The original was 16A!!!
Testing 12v winding loading...
Mockup of matl for raised sub-chassis...
Amp chassis now cut...
New sub-chassis cut and prepped...
Fabricating new tube mounts. The control grid flange of the tubes will be bolted directly to the new sub-chassis...
Tube mounts being fab'd...
Plenty of clearance for tubes...
Tubes modified for plate connections...
Tubes mounted...
Plate choke and parasitic chokes mounted...
Filament and cathode connection clamps...
Plating removed and clamps tinned for connection...
Fan speed dropping resistors in place...
Fan recounted to blow in across plates and Filament connections...
Plate glitch resistors installed...
Lower compartment wired...
Total Filament current, when installed with lower resistance, 3.5a. Much better than the OEM 16 amps!
A friend got this little amp in an eBay find and gifted it to me. It's a cool, 2-tube amp, from around 1966. I tapped the tank coil for 10m and it runs in my workshop (Studio B) with my converted Midland CB on 29.000 AM, daily. It boosts the little Midland to about 50 watts, and it piped up to a 6el Force 12 at 110'. These can operate on 15, 12, 10, and 6m. Here's a few pics...
I've had this tough old girl for over 30 years. It was time to do a little work, she had noisy controls and needed a few lamps replaced. This was an easy refresher, here's a few pics...
A friend lost the ability to raise and lower the anchor on his 44' Sailboat, due to a failed remote control. It had been stored in the anchor chain locker in the bow, and had been very wet, for a long time. The controller has been out of production for many years, and he was worried about how to replace it. I cracked it open and found the membrane switch pad to be destroyed by oxidation. With a little reverse engineering, I was able to figure out the interface with the membrane pad, installed a mechanical "on" pushbutton, and a "center off" spring loaded switch for anchor up and down. While not as pretty as the original, it got his anchor running without having to replace his Windlass control system. Here are a few pics...
Rough pinout of the chain locker connections for future reference.
This started as a barn find. Over the years, I've had a few of these, and found them to be pretty accurate when calibrated against a known good meter. It's also easy to add a 2000 watt range, but I didn't do it to this one. I decided to modify this one to be a passive peak reading meter, and here's the scoop...
Remote sensor make for easy installation in the shack...
It started as this dirty beast from storage in a barn...
Pin diodes and 1uF cap added...
220k resistor added in place of 20k...
Blue 500k pot installed in 10w position, 100k resistors placed in series with the 100w and 1000w cal pots.
This is the unmodified schematic...
...and this is the schematic with the component changes.
Basic peak reading mods for meters with movements of 1ma or less (200uA or less is better for response).
