All posts tagged eme



Well, last week was not a triumph! as I broke one of the mosfets in my 144mhz pa project.
I was hoping to receive the replacement before this weekend, but no such luck.

Did one qso by the moon last night @ 100 watts, but later I got some serious computer trouble and had to stop. Reason was me trying to do some upgrades at virtualized servers here, and it went bad, and things shut down. Been cleaning up all day and things are up and running again. Thankfully.

Also, one of my 4 bay NAS devices reported that it had a disk failure last night. So, now I have ordered new disks, larger ones as it was out of space anyway. Thanks to RAID no data was lost due to failure.

I am not motivated to turn to HF this evening, so Saturday night entertainment here is YouTube.

Temporary Yaesu Elevation Rotor Fix

Earlier I fried my elevation motor, and I was in need of a quick fix.
The plan is to eventually rewind the original 24VAC motor but this will take some time and materials I do not have for the time being.

The quick, non-destructive solution was to get a $7 worth 24VDC motor, and put that in to service.
All I had to do, besides the rectifier system, was to drill two new holes in the motor bracket and move the cogwheel over to the DC motor shaft.

The ZHENGKE ZGA25RP DC 24V 500RPM Micro Gear Box Motor have an unload speed at about 500 rpm, so the elevation is moving at about 1/5 of the original speed. However, this is more than sufficient when tracking the moon. The stall torque is also sufficient due to the low gearing.

I am considering to get a larger, faster and more powerful DC motor, but then I will have to ether do a non-reversal cogwheel modification or get hold of an another cogwheel that will fit.


Left: Original 24VAC motor.
Right: very small 24VDC motor fixed to the original bracket .


DC motor, rectifiers and relay in place.




The elevation on my old Yaesu G5400 failed last night. The load of winter with heavy snow freezing on to the EME antenna made it to heavy for the rotor, it stalled, then the elevation motor fried due to me not detecting what was going on.
The antenna is only a single antenna for 144mhz at 3wl length, a bit heavy balanced at the rear.
I think the G5x00 series I great for small SAT antennas, especially with its 180 degrees elevation movement. However, I think it is not sufficient to operate mid-size and up antennas in cold and snowy conditions. NOW! Tinkering about what to do next……..QRT for now, but will be back.


Will be participating in the ARRL EME 50 to 1296 MHz Contest this weekend. My band will be 144MHz in digital mode only. I have been working on giving my QRPp setup a 3dB boost for this weekend, but I had to abandon this due to mechanical difficulties. (Antenna staking hardware was not strong enough to hold the antennas straight, back to the drawing board I guess.) 🙂 My setup: Band: 144, mode: digital, antenna: 13,4dBd, power: 100-150w Good luck all!