Overview of the MX-P50M
This is just a quick listing of various rig-to-amplifier keying connections for the MX-P50M amplifier. I have searched far and wide for info on how to do this with my QRP rig collection, but have never seen all this info in one place. I hope this helps some folks out there.
Others have written about this amp in more detail, but I thought I'd put together a page to help with answers on connecting the amp to a qrp rig.
Since the amp only has manual bandswitching, a simple ground-held connection keys the amp for transmissions. The amplifier comes in a nice extruded case. I have two of these amplifiers, both purchased used (one off Amazon believe it or not), and both put out the following roughly equal values using 1W input FM from my 818 using 13.4V. Values were measured using an MFJ-822 and dummy load:
- 80M 15W
- 40M 18W
- (did not measure 30M)
- 20M 20W
- 17M 10W
- 15M 18W
- 12M 9W
- 10M 4W
Most of these amps sold off the evil Internet auction site include a power cord and an 8-pin mini-DIN for connecting to the FT-817/8 ACC port. Hook up, as always, should be something like:
The normal procedure for using this amp with your QRP rig is:
- turn off the amp
- set your rig to 1W output
- either use a resonant antenna, adjust your antenna for resonance, or tune your antenna
- turn on amp
- SELECT BAND ON AMP!!!
- key your rig
Just be careful that your tuner can handle the RF from the amplifier. I only want a bit more punch, so I only use 1W output from my rigs and look for about 20-25W output. The amp is capable of more output via higher voltages and RF, but I like to avoid heat issues and possible component damage.
Connecting the MX-P50M to a Yaesu FT-817/8
As most of these amps come with a cable, simply plug the mini-DIN into your 817/8's ACC port, then connect the two-pin wire to the amp. Polarization doesn't matter!
If on the off-chance you did not get a cable for your Yazoo, you'll need an 8-pin mini-DIN for the ACC port. Connect GND and TX GND to the mini-DIN:
Here's my setup with an LDG Z11, which is a perfect match for this amp, as it can handle up to 60W, though as mentioned previously tuning is done at 1W with the amplifier off.
Connecting the MX-P50M to an Elecraft KX2
Connecting the MX-P50M to a Ten Tec Argonaut VI
Connecting the MX-P50M to an Elad FDM Duo
Connection for triggering the MX-P50M from an Elad Duo is just as easy as soldering the GND (sleeve) and PTT (tip) of a 3.5mm stereo plug to the two keying lines of the amp.
Then insert the 3.5mm plug into the PTT out port on the back of the FDM Duo:
I set my FDM Duo to 2W output to get about 25W out on 40M. I have not run extensive tests yet, but will as some time in the future. Here's the setup with the amp, tuner, and FDM DUO (while listening to BCB MW):
Connecting the MX-P50M to a Xiegu X5105
The X5105 and CE-19 make for a quick PTT
connection for the amp. Amperage
draw is ~6A @1W input. To connect the amp, use the CE-19 PTT port, and solder a 3.5mm stereo cable and plug with sleeve
and ring connection per the diagram on the top of the CE-19. Then connect the X5105 port of the CE-19 to the X5105's ACC port. Turn off your X5105's tuner!
The X5105's SWR sweep function is especially handy with the Z11 tuner, as you can 'fine tune' using the tuner's inductor and capitance switches and watch changes to SWR in real time. Once your SWR is satisfactory, turn on your amp, first making sure that the proper band is selected, and then fire away!
Connecting the MX-P50M to a Xiegu G90
Connection is exactly the same as for the X5015 since the two rigs use the CE-19. Make sure to turn off your G90's tuner. If you want more output than the G90's 20W, use 2W or 3W input to the amp - NOT 20W!!!!
Connecting the MX-P50M to an ICOM IC-703
Apparently it is a pain in the ass to hook up an amplifier to the IC-703 without PTT isolation, separate circuity and custom cabling. The easiest way to accomplish this may be to buy one of W2ENY's IC-703 amplifier keying cables, which has the transistors and other components inside the hood of the 13-pin DIN ACC plug for the back of the IC-703. I may buy one at some point, but since I don't use the IC-703 in the shack and since the rig works fine at 10W for /P, i may not.
Connecting the MX-P50M to a Commradio CTX-10
The Commradio CTX-10 is one of the newest QRP kids on the block. It has 1-, 5-, and 10-W output and an internal tuner (which should not be used!). To connect the amp to the CTX-10, connect either end of the amp's keying lines to pin 2 and pin 6 of the CTX-10 6-pin mini-DIN accessory port: