So I recently bought an untested KLM 10-140BL amp at a hamfest, for $20. I finally got around to testing it today. It’s a 140w linear amp for the 2 meter amateur band, 144-148MHz. It does not have a preamp. It will take 10 watts of drive power and output 140 watts.
The front has just the IN/OUT switch to manually switch the amp in and out, and a lamp to indicate it is operating. It also has a pin on the back for automatic TX switching. It appears that even with the operate switch on, it is still in bypass until there is RF in it. When I transmit, I hear a relay click in the amp, the light comes on, and it outputs power.
The back has only the antenna ports and the power / PTT connector. It’s a 4 pin Cinch-Jones connector. The top two pins are for the 12v power supply. The bottom left pin is PTT, and the bottom right is GND.
I tested this amp with a Kenwood TS-700a, and MFJ 300w dummy load, and an MFJ-945E tuner, for measuring the output. It’s an HF meter so it will not give an accurate reading, but its enough to see if there is any power output.
I did not have the correct power cable, so I had to improvise. I used a T connector from a VHF radio and another flat connector which may or may not have a name.
I plugged everything in, put the radio in CW, hit TX, and nothing happened. Then I realized I am stupid and I had one of the radio’s memory channels selected, not the vfo. I fixed that, hit transmit, the light on the amp came on and I heard a relay click.
And heres what the power meter looks like:
It is amplifying! I don’t know if I am getting 140w, but it is definitely more than with no amp! I’ll have to get a power meter and measure the actual output. Note: the SWR is not actually infinite, thats just the meter. It may be slightly higher than 1:1 but since this dummy load is rated to 650MHz it should be good enough.
I now have an excuse to get a big yagi.