Hy-Gain HDR-300A Conversion, pt2

 The previous blog demonstrated the ability of this satellite dish elevation controller to be converted to a 360° azimuth rotator controller. 

I mapped the HDR-300A wiring to the rear receptacle, changed the receptacle to screw-type terminal strips, installed a pot for "zero" calibration, and tested this setup on another HD-73 rotator motor. So far, so good! Here's a few pics and video...

First, I mapped the various terminals and their function...

Here, I made a chart of the internal wiring colors to the output connector, and their function.

I installed a 300 ohm pot for "zero" position calibration...

Down below is the output connector location, when it was removed.

I installed to terminal blocks...a small block for feedback pot connections, and a larger block for the higher current motor and brake connections.

I mapped the original Alliance rotor controller connections and their motor functions.

More mapping the old vs. new controller cross reference...

Feedback pot not yet connected, while sorting the motor control functions.

The gearmotor and feedback pot assy from the Alliance HD-73 antenna rotator.

The motor run capacitor that must be used, the HyGain controller originally connected to a basic ac motor that required no capacitor.

Hy-Gain HDR-300A Conversion, pt1

This was is an old Hy-Gain HDR-300A 180° satellite elevation positioner I got from a friend. It was kinda cool looking, and I wondered if I could mod it to use as a conventional 360° azimuth controller for my tower mounted antenna stack and HD-73 antenna rotator. It was kinda beat up, the bottom was damaged from being dropped (it has a large transformer and is kinda heavy), the case was scraped and scratched, and it was pretty dirty.

The most important step was to see if it could be modded for 360 operation, and be interfaced with the 75 ohm feedback pot in my HD-73 rotator assembly. 

Here's a few  pics and video...

I used external pots to simulate my 75 ohm rotator feedback pot. This unit places 5vdc across the rotator feedback pot, and looks for a 0-5vdc return signal to translate to 0-180° of movement. Calibration would allow for a negative position of -90ish degrees, instead of displaying a positive declining value of 359° or less, when rotated below North via West. However, I could change range on the digital converter, and display to over 600° positive. I decided to set the controller up to rotate North to North to manage this issue, as opposed to South to South as in most typical rotator controllers. 

Once I settled on the rotator stop point as being North (0 degrees), I calibrated the digital display to range from 0 to 360 degrees (0 to 5 volts in). I did, however, need a variable 0-300 ohm pot to tweak the 0° reading when the rotator was at North via East (full ccw). Once that was done, it displayed properly and was amazingly linear! Above is my chicken scratch drawing of the electrical mods to the display circuit...

More on the conversion in the next post...

Johnson 323A Messenger Repairs

 This is a Johnson Messenger 323A. A friend had this stored away, then wanted it repaired after a long break from use. It was unbelievably clean, in the original box, was in the original plastic bag with no scratches, etc. The mic head had been removed for some reason, and there was no rf output. 

I repaired the mic, troubleshot and replaced the RF final, reconnected the modulation limiter, and gave it a full alignment. This is like a new radio, a time capsule back to about 1976 :-)

Award Tracker 3.3.3

 I last mentioned this back in 2011, and am still using it. It's a cool program to help with Awards hunting, and it's free. It was written by David W5DJT, and still being updated and maintained by him. It's super handy and easy to use for WAS, WAC, DXCC, County Hunting, 10-10, RAC, etc. If you have any issues, want something added, etc, you'll find David at his email listed on QRZ. His website is W5DJT.com . Here's a short video...

Zenith 7H02Z Restoration

 This is a 1951 Zenith 7H02Z table radio I restored for a friend. It was cosmetically a bit rough, and had numerous electrical issues: intermittent I.F. transformer, bad electrolytics, several out of tolerance resistors, dirty tube pins, 1 bad tube, bad chassis grounds, etc. Once that was all resolved, it was brought up on a variac, a full alignment, and was playing nicely. 

Cleaning all the nicotine from the cabinet was a task, but that and polishing turned out great. I had to paint the speaker grill and polish the Zenith badge. Overall, this restoration was a success. Here's some pics and a few videos...