What's wrong with the Micro PA 50?
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- Опубликовано: 24 июл 2024
- In this video I show how I reworked the SWR sensing to be a little less sensitive. Remember make sure to do your own findings and if you decide to do this mod do at your own risk. Make sure to check your antenna's SWR before using this amp! I purchased my amp from Ebay and a U.S. seller.
***NOTE, I ended up changing the 33 ohm resistor to a 22 ohm resistor to keep the swr closer to actual swr as per my analyzer about .2-3 lower. ****
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**** NOTE: I changed the 33 ohm resistor to a 22 ohm to get it closer to actual swr, make sure and check your amp.
Nice fix - didn't look too difficult and it worked!
I have added an antuner AT-100M downstream of the amp. I can run short random wires in the field with the amp and a uSDX+ V2. I end up with 30w peak SSB and I am good with that. It all fits in a condor molle first aid kit. A 6ah battery keeps the amp happy for a long while. Radio and tuner have built in batteries.
Great and useful video Chuck
Nice! Glad it was a quick & easy fix for you.
The designer of the amp commented on another forum that the meter is accurate and to try RF chokes on the antenna before modifying it. RF feedback can make the meter report higher than actual swr
I did exactly that and my problems went away. Put a bunch of ferrites on the input and on the coax to the radio. Works great with my Xeigu 6100
Yes I saw that and I do have a choke in line. I will do more testing though.
I have not had any of those issues. Good fix Chuck. BTW, I have hit 72W on the amp before the protection kicked in.
Solid work Chuck 👍
Thanks Ape it really seems to be a good little amp!
@@KK6USYHamRadioAdventures David Trewren has a video showing the amp with a tuner on an X6100. I have the same set up and use it with both the Xiegu and a uSDX radio. I like it.
You may have covered this before, is it true that the input power can be internally adjusted on the PCB to 10W using the potentiometer?
I looked it up; it’s adjustable using the onboard potentiometer. Kinda cool feature
We installed this amp inside a big /p radio box. The IC705 does not provide enough drive for the 300W linear amp. Unfortunately, the PA50 did not work. Input VSWR was very high. Not sure why. Found a "manual" online but got no clue. My feeling is that a PTT line is needed. Manual says, it can run without a PTT but no idea how to set that up. Any help is most appreciated. 73
I bought a pa50 for my X6100 wanted a little more power for my CW POTA
I would check that VSWR across all frequencies and values to see if it really is consistent. I have not seen the schematic so it isn't clear where that resistor is going, but usually these types of detectors are quite accurate at HF and it is important that that resistor is 50 ohms. Putting a 22 across it pretty severe. I would also check the power indication, but that's the other resistor. Why not use an SMD resistor to reduce the gain across the bridge output? It would make a neater job.
This is what I had and I'm fine with it. I did check other freq. also and it seemed consistent.
@@KK6USYHamRadioAdventures Fair enough. As long as it works. That resistor might get a bit hot though in full carrier modes like FT8 as it looked like an 1/8 watt and the original looks like a 1/2 w. An easier fix is to put another 10k across the detector output, you would need an SMD and they are fairly small so would need a magnifier. I tried to link the reference but youtube deleted it. - it is on the sota web page, easy to find, with a nice picture.
@@mikewillis1592 The original is 1/4 and so is the one I added
you should recalibrate SWR bridge by serial console as described in the manual instead of "sculpturing"
I am not sure this is really needed. I have this amp and it works great. If you put a common mode choke on it, I think you will get better results. In any case... there is a firmware update that address the SWR measurement. I updated the firmware and use a common mode choke and do not have any issues.
My understanding is that there is a firmware update to correct this. Ape did a recent video on it. This fix looks easier though 😂
Yes but he didn't check to see if it fixed the problem mines works great now!
The firmware upgrade looks like a pain in the butt…this definitely looks easier. I don’t own one of these units yet. If the firmware addresses the issue I’ll buy an upgraded version if and when available. Nice addition to my KX2 I suspect
@@joen8joe231 Yea I have been using mine with the Hermes lite 2 and it does 50 watts with no problem and my swr reading is pretty close now.
The fan is a bit noise sitting in the shack
@@KK6USYHamRadioAdventures can you try with the slider of hermes to -7.5db ,drive closed i mean and tell me what the output is? i want it also for portable abut also to trigger another amp that needs 10 to 13w max (rm italy 300v plus ) Thanks
@@SV1RXI I will try it and get back to you. I have used to do that to my AL80B and at 50 watts get 500 out. Not sure it will be low enough to stay below 13w.
Manufacturer warns against this mod… there is a firmware update
Icom is due to announce the new IC-PA705 in March 2024 for April release
A nice easy fix for those who can see well.😊🥸
Ate they generally okay other than that Chuck?