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Categories | Amplifiers: RF Power - HF & HF+6M | Elecraft KXPA100 Amplifier Help

Show all reviews of the Elecraft KXPA100 Amplifier

You can write your own review of the Elecraft KXPA100 Amplifier.

K5MF  Rating: 4/5 Mar 20, 2014 00:27  Send this review to a friend!
Works Pretty Well  Time owned: 0 to 3 months
This is a good little amp and it works pretty well. I am happy with it as I can get 110 watts out of it as measured on an external meter but I typically run it at about 80 watts. I rate it a 4 because there a couple of niggles everyone needs to know about. None are showstoppers but hey it is a pretty high priced amp.

The mechanical design is well a brick. It looks like the mirage 2m amps. I think they could have done better.

While the build from kit was easy, it is not easy to get back into the kit if needed. In fact you pretty much have to take out 32 little screws to get it open at all. I worked for a company that designed computers and servers, there could be no externally exposed screws and it had to open with one hidden knob, so it can be done - those guys were mechanical engineering geniuses!

The amp is designed to talk to the KX3 and computer through a serial interface, this means you daisy chain the KX3 to the amp to the computer. I have found this can cause comm problems with rig control and software programs.

The ATU on the amp is not as good as the internal ATU in the KX3. I find that the ATU in the amp stops .1 or .2 SWR units higher than the KX3 ATU. I've also noticed that in some instances the tuned SWR is lower than the operational SWR. I am not sure what is going on with that but I am working with Elecraft on it and am confident we will come up with an answer.

I've also noticed that when I stop transmitting, there is a significant delay in the response of the front panel LEDs. The 25W LED and the SWR LEDs will stay on for 1.5 to 2 seconds after key up.

Finally, when the ATU tunes, the firmware puts the amp in bypass mode so it is just the KX3 working with the ATU to tune. After tuning, there is a about a 1.5 second delay before the amp switches back in. So if you tune up and then try to transmit too quickly, you will be transmitting without the PA and at the lower tuning power.

Maybe I just have a problem with my ATU and I will continue to work with Elecraft to figure it out. I think the AMP is fine and does what it is suppose to do, but I may have an issue with my ATU.  
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