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.

Saturday, April 21, 2018

6M Yagi Rebuild, 3rd evening...

I got a little more done today, almost ready to attach the elements to the boom and tune it. I mounted the boom on the test tower section, adjusted the element lengths per the manual, painted the repairs/splices in the elements, drilled the repaired elements for the boom mounts, and capped off the ends of the elements to keep water / insects out. Here's a few pics...

 The repaired boom is now attached to a short section of tower in the back yard for testing....

 Drilling the repaired element centers for assembly onto the boom mounts...

 Lengths of the elements are now adjusted per the mfg specs...

 Element splices / repairs now painted...

The ends of the elements are now capped off to keep insects and water out...


Dave WB4IUY
http://www.WB4IUY.net













Tuesday, April 17, 2018

6M Yagi Rebuild, 2nd Evening...

I got in from work a little before dark today, and decided to work on the 6M yagi project a bit more. I spliced the broken sections with 1/2" type M hard copper from the hardware store... This stuff is stronger than the aluminum it's repairing, the short sections won't add much weight to the yagi, and it's CHEAP :-)  I've repaired antennas like this that held up 20+ years and are still working.

The center sections of the elements were supposed to be 48" long, each. They were mostly broken right around the boom attachment point. I cut out the crimped sections, cut the copper long enough to extend into the aluminum 3" on each end, and restored the center sections to 48" long. I drilled the tubing and secured it with 1/8" pop rivets, then used the low temp flux core aluminum brazing rod to solder the parts together securely for a continued good electrical connection. The brazing rod comes from Home Depot, and is the type that melts about 700 degrees F... This allows the use of a small torch to handle the job. 

After the elements were repaired, I did a quick mock up in the yard... see the last pic. Day 3 should allow me to get the boom mounted on my test tower, and get it marked up for test assembly. Here's a few pics...

Installing the splice sections, drilling, and pop riveting.  
 
Checking for straightness, after returning from the redneck tubing straightener, described in my previous blog...
 
Cutting out the damaged sections...

Checking more elements for straightness...

The matching section is in pretty foul condition...

 I soldered the copper splices into the aluminum elements for continued good electrical contact...

Propane Torch and low temp aluminum flux core rods...

Another element after soldering the copper splice to the aluminum element. 

A quick mock up in the back yard to get a feel for the element layout. It's beginning to look like a yagi, again :-)


Dave WB4IUY
http://www.WB4IUY.net
















Monday, April 16, 2018

Beginning the repairs on my 6 Meter Yagi...

This is a Cushcraft 5 element 6 meter yagi, another fatality of my tower crash back in April 2016. I'm getting things repaired and reinstalled, slowly but surely. We joked around on the air and called all of my Cushcraft antennas... Crushcraft, since they were all crushed in the tower failure. 

Today I pulled all of the parts of the 6m yagi from the antenna wreckage pile, and began disassembling everything. Some stuff was bent, so I straightened those items and put them to the side. One of the elements (1st director) was actually straight... I couldn't believe it, considering the condition of everything else. Here are a few pics of the first evening's work... 

 This is pile, after it was pulled from the tree and tower wreckage about 2 years ago...

I laid it out in the back yard to figure out the component layout prior to complete disassembly...

 Broken stuff...

 ...more broken stuff...

..and more broken stuff.

The driven element is in foul condition...


The boom mount and element supports were twisted and/or broken along the length of the boom...
 

I began work on the boom...it was bent up pretty good...

I employed my red neck tubing straightener that I've used before... a pair of twin trees in the woods behind my house. Trees work pretty good for this, their surface is soft and doesn't tend to wrinkle or crimp the tubing at the points of contact while straightening it. I first straightened a motorcycle crash bar in those trees about 15 years ago...

Here's the boom...nice and straight!

The 1st director was warped up a bit, so off to the red neck tubing straightener it goes...

...and it comes out nice and straight! Next, I have to pick up a short piece of tubing to make splices for the broken elements. More on that in the next blog update...


Dave WB4IUY
http://www.WB4IUY.net







Monday, December 11, 2017

Aftermarket Stepper Motors for Icom IC-756 Auto-tuner

This may be old news, but just in case, here it is... I just repaired the auto-tuner in my IC-756 (not a pro version). One of the motors failed. I found a procedure online for repairing the motor, but also decided to try an aftermarket replacement motor. The OEM part number from Icom was MP28GA, and their new # for their replacements is MP24ZA. This happens to be the same replacement part used in some Yaesu auto-tuners, their part # is M2190023. The Icom part costs about $35 + shipping, the aftermarket part is $4.95 + shipping. Looks to be the same part, except that the aftermarket part has a brass output shaft vs. plastic on the OEM. 

This looks to be the same motor used in several Icom HF rigs as well as Yaesu.
I bought the aftermarket motor from https://www.adafruit.com , and it is their item #918 and cost $4.95 each. The plug is slightly different, but I was able to slice off a piece of the plastic clip from the socket on the tuner PC board and it snapped right on, but you could simply replace the connector from the original tuner motor...the wiring colors match perfectly. 

There's a great Youtube tutorial on how to repair the original stepper at:

http://youtu.be/UdY6RhNOCWg

 
 Comparison of back side of stepper motors...

 Comparison of front side of motors...

 
 Tuner is under this board...

 Board remove, exposing metal cover on tuner...

 Metal cover removed, stepper motors seen in lower RH side of pic. Remove screws from tuner, lift it up, loosen screws on motor coupling, and replace the motor. Very easy!
 




Dave WB4IUY
http://www.WB4IUY.net





Display Transplant into an Icom IC-756 (non-pro)


 Before...

 After!!

 The display has a more brilliant color than this, my phone cam just doesn't do it justice!



This blog is about replacing the LCD display in a Icom IC-756 classic. The displays in these radios haven't been supported by Icom in several years. This is an attempt to archive info & notes from myself and others about different displays used. I'll probably add to / edit this blog as I continue to test & install more displays.

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Winstar WG320240D-TMI-TZ# display: When installing this model, I had tried to drive the display contrast input (display pin 13) from the 756 contrast output (DV0, radio pin 1). It works, but over the period of an hour or so, one has to go into the radio menu and readjust the contrast setting. It seemed to be a thermal drift of some sort in that circuit. After working with the mfg, I discovered a few things:

1- The display generates it's own -25vdc and outputs it to pin display 12. The -30vdc from the radio pin 2 should not be connected to the display. The display is temperature compensated and it varies the -25vdc output at display pin 12 accordingly.

2- When driving display pin 13 from the radio, it ignores the display's temp compensation, thus causing the contrast "drift" or instability. Installing a linear potentiometer of 15k, high side to pin 12, low side to pin 14, and wiper to pin 13 allows the display contrast input to reference the temperature compensated internal -25vdc supply of the display, and I've found the contrast to be perfectly stable. Keep the pot as close to the display as possible, leads short...

3- I prefer to have the contrast adjustment where it can be easily reached, as contrast is somewhat subjective and based partially on the viewing angle. An internal pot is fine, but I like to be able to adjust it easily. I found the lower LH side of the cabinet (just below the handle) to be a good, easy-to-reach location for this. When mounting the pot somewhere that requires a few inches of wire to make the connection, install a 100pf capacitor across the high and low connections to the pot. The -25vdc output of the display acts like a nice antenna to radiate processor noise to the rest of your rig, and I found 100pf seems to be adequate to resolve the issue.

 
 100pf cap across high and low terminals of the remote contrast pot I installed in this radio...


4- Source a +12vdc switched point to build the 5vdc regulator for the LED back light. I use the point from the 4-pin rear panel  accessory port. Use a 7805 regulator and heat sink to chassis, and a 33 ohm 1/2 watt resistor in series with the output to the back light, to limit the backlight current. Open coil L103 along side of the HV compartment to shut the CCFL HV supply off when using displays with LED back lights.










5- If you plan to buy a Winstar display, try to locate the WG320240D-TML-TZ# instead of the WG320240D-TMI-TZ#, it is more easily viewed from above the radio.

6-  APlus Displays: AG320240D-TTI-TZ# seems to be the same as the Winstar display

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Stanley GMF32024ABTW1X: The Stanley display found by Rick K4PQ is by far the easiest to install electrically (no back light mods required and seems to be temp compensated in some other way) .

1- Contrast setting is very stable, the current requirement at display pin 13 is only a few MA (contributing to stability).  Connect the -30vdc supply from the radio to display pin 12 via 2k 1/2 watt resistor. Be sure to turn the trimmer down on the sub-logic board to about the 9 O'Clock position.


2- The back light is directly driven from the radio CCFL HV supply with no mods. This is not a polarized connection and polarity is not important.

3- This display has the best viewing angle of any of the displays I've tested / installed. It is viewed from above the radio easily, best of all the displays I've tested in this blog.

Can anyone find another source of the Stanley display GMF32024ABTW1X ??
 
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I'm waiting on a East Rising ERM320240SBS-1 to test now. It also looks like the New Haven NHD-320240WG-BxTGH-VZ#-3VR will work, but much more expensive.

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Folks have physically installed these various displays in the metal sub-chassis a number of ways from building brackets, re-drilling holes, etc. I prefer the Hot glue method recommended by Rick K4PQ...quick, easy, and very solid.

I use the Dremel tool to remove the little folded edge from the sub-chassis for best fitment...


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When disassembling the face of the radio from the sub-chassis, I've found cutting small cardboard tabs and inserting under the clips around the perimeter makes removal much easier.



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Using the original display as a donor, cut the plug for the ribbon cable and a piece of the board away, and stick it to the new board with thick double-side tape as a sort of "break-out" board to help with assembly. The numbers are backwards on the cut-away board from the actual ribbon cable and socket on the radio main board...makes no sense, but the cross reference chart takes this into consideration. Mark the ribbon cable TOP surfaces and make sure to not get the cable reversed during re-assembly.








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When removing the front panel from the sub-chassis, slip the rubber cover off of the main VFO knob, loosen the set screw found below it, and remove the long silver screw from the VFO brake.




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When removing the sub-logic board, be sure to unsolder the S-Meter connections to allow the boards to separate.


Dave WB4IUY
http://www.WB4IUY.net














Sunday, November 26, 2017

Antenna work - 11/26/17

Finally had a little time to get back on my tower and get more antennas pulled up. I broke my Force-12 6 element HF yagi into 3 sections, pulled it up the tower, and reassembled it from up top. The assembly went well and it was an easy one-man job. Once in place, I got the feed line and rotator cable pulled up and connected. Here's a few pics from the work...

 A shot down the tower as I pulled up part of the yagi...


 Looking south at the reflectors...


 Looking north at the driven elements...


 Looking at the horizon to the west from about 105' up...


 A pic from the front yard, the yagi sits at about 105' up now...


 Looking north, over the boom, cam at about 107'...


 Looking down the tower, my feet are perched on the rotator plate...



 The view to the west is awesome from this height...


 Looking up from my driveway, things are beginning to come back together, finally.


 Looking up from the northern part of my front yard...



Time to build the next antenna for the stack and get it in position #2!


Dave WB4IUY
http://www.WB4IUY.net