Micro PA50 Plus HF Amplifier First Thoughts

Adding a 50 Watt amplifier to my ICOM-705. Today I connect and test a Micro PA-50+ amplifier from AliExpress. Probably the best lower cost QRP Amplifier available.

[@loraz0]

It auto switches bands. My routine is to change band on radio, turn off amp to tune new band, it will switch then as you tune. Turn amp on and transmit. If your tuner has memories, just change bands, the amp will switch almost immediately. They are solid amps, I think you will like it.

[@barrykery1175]

Can't beat it for the price. Neat little amp. Barry

[@jayd8935]

I look forward to your further testing (and videos on how it sounds on the other side) with great interest!

[@HamRadioRocks]

Thank you for checking my videos out. I especially enjoy A/Bing antennas! Playing with antennas and radios keeps me out of trouble. 😂

[@amnchode]

As a few have stated, it is frequency sensing, so all that is truly needed is to have it installed inline with the antenna. That said, I really like mine. It pairs very nicely with my X6100 & Antuner AT-100M ATU, as everything is very compact and easily packable. It works rather well with my DX Commander Signature 9 (w/80m inverted L element swap), and I was able to 6 band both of the recent A25R and W8S DXpeditions, including an 80M QSO to W8S from South TX.

[@kenharvey9714]

I have recently bought this amp to use with my Xiegu X6100. All I did was connect the rig to the amp through the antenna socket, and antenna to the amp, then the amp automatically switches bands. This should also work with your Icom.

[@HamRadioRocks]

I’ll have to check that out, I’ve been manually switching it.

[@a.v.stechs9398]

Dear sir it's working with usdx 8band qrp chinese radio

[@alexjh47]

How sensitive is it to SWR? I hear the original versions would shut down even on an SWR of 1.7

[@jameslee522]

Need to try this with a trusdx

[@DutchmanRadio]

I have a TruSDX now and this amp coming in now, I might give it a shot and let you know

[@jonhult5027]

I have one of these. Good amp but watch for random SWR spikes in CW. I modified mine to key via the key line from the radio. The frequency/band switches automatically.

[@mrtechie6810]

What do you mean, watch for random spikes?

[@jonhult5027]

@@mrtechie6810 , when in CW and transmitting, a random “open” will occur in the amp which causes a full deflection SWR spike as seen by the ICOM 705. TX delay settings had little effect. Root cause: the TX relay is tied to the “RF sense” feature; it was missing a relay closure randomly. Fix action: I pulled the keying relay from the board, reassigned the 1/8” socket to the relay via wire, pulled 5VDC from the the board, and then resoldered the relay to the board standing on its own leads. As the 1/8” jack never worked as designed (it was supposed to sense the 705 or the Xeigu radios when selected), it is now plugged into the 705 key line. When the radio keys and drops the key line to zero volts, the relay sees a difference in potential on one side of the coil and closes. Now I have perfect CW with no spurious SWR spikes. I now use a cable to control amp keying…. Also did the firmware update to 2.6. See KZbin or Google about the update.

[@migalito1955]

I have recently picked up the less expensive OGS-50. Only tested it using 0.8 watts as input & it output 25 watts. I heard the OGS-50 does not necessarily have a good impedance match between the source rig and the amp's input. I am waiting on a soon to be published easy fix for this before I use the amp much. This leads me to wonder if your amp has a similar issue. If so, I suppose the reflected power could damage our PA on our rig.

[@mrtechie6810]

The Micro PA50(+) is supposed to be higher quality. It's worth the price difference.

[@honeybadger6127]

any new updates on this amp? Is it still working ok?

[@HamRadioRocks]

I haven’t used it in a while as my antennas are down temporarily at the QTH. I should have everything back in a few weeks. I’ve been looking forward to testing it more. 73

[@godfreydebouillon8807]

Can this be used with XIEGU G90 using SSB? Thanks!

[@HamRadioRocks]

I’m pretty sure you’d be ok. Although I believe the G90 puts out 20 watts stock, so I’m not so sure it would be of much of an s-unit benefit to get 30 more watts. I was really on the border picking this up knowing the 705 on battery does 10 watts.

[@pnwgeek]

My PA 50+ does not work on 30m or 15m. Says "BYP" in the upper right. Is running 2.8.5. Anyone else experience this or have a fix?

[@pnwgeek]

Figured it out, There is a multi-click option that is missing from every manual I can find, that is for "30/15m Open/Close". This comes up after 8 clicks. Do the 8 clicks until it says "open". Then power the amp off and back on. This seems to enable/disable 30m and 15m operation. Same as for the 7 click menu option for "17m/15m SWR On/Off". No mention in the manuals, but turns the SWR meter on and off for 17 and 15m (no power cycle needed).

[@michaelr5164]

I have the same problem...glad you found a fix...but doesnt 8 clicks set unlimited mode?@@pnwgeek

[@michaelr5164]

I have the same problem and have the same 2.8.5 firmware. I like your fix but I thought 8 clicks puts the amp in unlimited mode.... Update:. I just tried your fix and it works perfectly, thank you. Apparently in this version, 8 clicks do not put the unit into unlimited mode but in fact does exactly as you stated. So either they eliminated the unlimited choice or maybe its something else like 4 clicks or 9. There has to be an updated manual out there, finding it is the problem. Thanks again, I have been searching for weeks just to find anyone who had the same issue until I found your comment.

[@jsieb]

​@@pnwgeek It probably comes disabled because the amp has third harmonics on 30/15 that don't meet the spurious emission requirements in the US.