WB4IUY's Random Blog

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 is a blog of various info about my Ham Radio operations and activities, projects, and opinions. Visit www.WB4IUY.net for the lowdown at WB4IUY.

Sunday, June 17, 2018

Rebuilding the old Diamond X-500 Antenna...

The old Diamond X-500 2m/70cm vertical is finished, reassembled, and up on the test mount. This one had a rough life... Back in 2016, the antenna had quit working. When the tower fell in April '16, the fiberglass portion also got snapped off just above the aluminum mount. I tossed it in the scrap antenna pile until a later date. Fast forward to May of 2018, I finally got to it while rebuilding all the damaged antennas,

The metal base had to be cut away with tubing cutters to gain access to the base loading coil, as the threaded section had become seized. During disassembly, I discovered the series and shunt capacitors in the base were toasted. Closer examination revealed the top part of the fiberglass enclosure was split and the metal cap was smutty black...I'm guessing it had taken a lightning strike. The condensate drain hole was also plugged up with _stuff_, so that was cleaned out for proper drainage. 

The capacitors were originally some low voltage style. I replaced the series cap in the feed with a nice 10pf 2.5 kv version, and fabricated the 1.5pf shunt cap by twisting two pieces of wire with 600v insulation, while reading the value with a capacitance meter. It was all cleaned up, the contaminated foam removed from the coils, the stacking couplers were sanded to remove crud, the top fiberglass section was repaired with fiberglass resin, a pvc sleeve / splice was installed over the broken section at the bottom of the fiberglass enclosure (radome) and 'glassed, and the bottom aluminum section was brazed back together with low temp aluminum brazing rod and a propane torch.

I got it up on the test tower this morning and ran some tests, and all was well. SWR match is good, and some on the air tests proved that it was working pretty good. I'm ready to install the decoupling elements, and get it up on the tower on a sidearm (I'm not top mounting it, these things seem to be lightning magnets when put on top of tall towers!).

 Parts of the antenna are in this pile of scraps...

  Internals out of the radome, partially cleaned up...

 Nasty couplers...

 Damp contaminated foam on the coils had to be removed...

 
 Had to use a tubing cutter to cut the bottom off, to gain access to the base loading coil.

 Yuk... corrosion and ratty looking caps...

 Shunt cap blown apart...

 Shunt cap...

 I split a piece of pvc pipe to stretch over the fiberglass tubing, made clean cuts on the broken fiberglass, wetted the parts with fiberglass resin, and assembled...

 Fiberglass resin applied to all parts...
 
  Fiberglass cloth laid over the splice...

 Fiberglass CSM (chopped strand matte)

  Base cleaned up, ready for reassembly...

 1.5pf cap (dicky) fabricated and installed (in red).

 
  10pf series cap installed... I slipped a piece of thick heat shrink over this assy, before reinserting it into the aluminum housing...

 All reassembled, I used GE silicone caulking to seal all of the joints, and bolted it to the top of the test stand in my back yard. SWR was good, and it seem to work OK. Another antenna resurrected from the scrap pile


Dave WB4IUY
http://www.WB4IUY.net



Repairing the Vizio 42" TV...

This isn't ham radio, but it is electronics related. The Vizio LED TV in the living room started having trouble with a dark band at the top of the screen, and progressed until it was difficult to watch. It looked as if the back lights were failing. I sourced the parts online for $29, and broke into the TV tonight after dinner. Took about 2 hours to repair and reinstall, much cheaper than a new TV!

 The dark band has almost moved all the way down the screen, making it difficult to watch.

 TV laying face down on a blanket toss on the bed to protect it while working...

 Rear cover removed, exposing the two boards and a zillion screws around the perimeter...

Back, face trim, and the LED screen removed and propped up against the wall...

 White backlight diffuser exposed, after the face trim and LED screen removed...

 Backlight frame exposed, with the old back lights removed. Note the wiring harness on the RH side...

 New back lights, ready for installation...

 New back lights installed. I powered the TV up to check them out... The bottom strip of the old back lights is all that was working when I checked them!

 Everything going back together...

 About to reinstall the back...

 Old back lights and harness heading to the waste bin!

 Only took about 2 hours, and it's all back in operation. I got the lights from www.ShopJimmy.com

Dave WB4IUY
http://www.WB4IUY.net











Wednesday, May 30, 2018

Repairing the IC-211 Receiver, again...

This isn't my first rodeo with this 40+ year old rig from the mid-70's. It uses a dual gate N-Channel FET for the 1st RF amp... It's very sensitive (single tone detectable down below .01uV!), but it is also easily blown. I think this was knocked out when lightning struck a tree about 100' away. I repaired it last back in 2015, when I fried it while operating full tap on the 160 m band, when the 160m antenna was only about 10' away from the 2m SSB yagi :-)





I snatched the case off of it to have a look...it was only hearing about 3uV minimum, but when I injected a signal on the output of Q47, it came alive. Yep, bad FET.

This is Q47 after I removed it. I dug around in the junk box a bit, but didn't have any more of those. This was a ELM222, but the original was a 3SK40. 

 



Well, I scratched around in my spare parts and found a RCA 148085, similar to a NTE222, and decided to give it a try. Sure enough, the receiver sprang to life and has a really sensitive front end, now.




Q47 as seen on the schematic...




This is the bag of the one FET I found in the workshop with a suitable operating frequency range.




Here's the IC-211, back in it's operating position and ready to go. I was able to work Alex KC4PHJ over in Apex and was hearing him fine, so combined with the rebuilt 2M SSB antenna I put up last weekend, my 2M SSB station is back on the air!

Dave WB4IUY
http://www.WB4IUY.net









Sunday, May 27, 2018

More of the yagi's back up on the tower...

It was a long, tiring day, but what a great feeling to look up and see it all beginning to come back together. It's been over 2 years since the storm took my antennas and tower down. Today we got more antenna work finished, and it's much closer to being completed. 
 

The 5 element yagi for 6 meters and 13 element yagi for 2 meters SSB (horizontal) are now installed at 108' and 111' respectively, feedlines installed & terminated, and other tower maintenance done. Still have to install stuff for 2m / 220 / 440 FM, and raise the 160, 80, & 40 meter antennas from 65' to abt 100', and 30 meters to about 90'.

 The 13 element 2M SSB yagi propped up against the house, waiting to be pulled up the tower.

 Looking to the NW at about 80'. You can see the top guy wire coming down from above in the photo.
 
 The view as I was climbing up the tower. The work / tool bucket was already tied to the tower near the top...

  Looking down from the rotator shelf at about 100', at the 2m SSB yagi to be installed with horizontal polarization at about 111' on the tower.

 Looking up at the mast where the yagi's will be installed...

 Looking to the west from under the 2M SSB yagi at about 111'.

 Looking up through the HF, 6m, and 2m yagis while on the tower.

 Looking to the west at about 105', just below the Force-12 HF Yagi...

 View to the east at about 105', under the Force 12 HF yagi


 
 Looking straight up the tower at the yagi stack. More antennas coming to fill that space :-)

 An opening in the trees frames the view of the new yagi stack from the back yard.

 Looking up at the tower and yagi stack from the rear deck.. More tower work coming soon!


Dave WB4IUY
http://www.WB4IUY.net