MX-P50M HF Amplifier For QRP Radios

[@loughkb]

I have one of these also. After a viewer complained about it's lack of linearity from my review, I did some testing for another video. I found that it's amplification falls off above 3 watts of drive and it starts to splatter from the compression in the amplifier. Not terrible, but it was splattering into the suppressed side band. So I never drive it with more than 3 watts, and I still get a bit over 30 out of it. I also did a single transistor mod on it to make it work with more radios. By default, the keying line on the amp is actually directly connected to the two relays that put it into TX mode. The keying line requires your radio to sink over 30ma of current to key the amp. It won't key with some radios, including the Icom 705. I add a single PNP transistor, one resistor, and one diode as a relay driver. Now it only takes about 1ma of current for the radio to key the amp. You can find the vids on my channel by searching for my call and MX-P50. 73 DE KB9LRW

[@TechMindsOfficial]

I’ve watched your video on this, definitely worth a watch if you need to modify the PTT! Thanks 🙏

[@stevejones8665]

@@TechMindsOfficial Nice to see Kevin and Rodney bumping into eat other and having a chat, or is it Dave 😉😊👍👍. I remember having a similar problem with splatter many moons ago not long after I was 1st licenced, i was using an FT290R into a Microwave Modules 100Watt linear and found the splatter completely disappeared when using vox TX switching rather than the hard wired ptt. Obviously it was due to RF pickup from the ptt lead. I was operating from my QTH in Hemel Hempstead at the time and used to work for Lucas Aerospace (sadly long since knocked down)😔😭. Really interesting video 👍👍.

[@aw7425]

Both of you gentlemen are very helpful. 73

[@youtube.youtube.01]

Matt - This is the way all videos should be! Highest praises for your excellent work! Your advancement of the art of radio is well done and worthy of subscription.

[@RyanHannaProductions]

Glad to see someone putting this to the test! I've seen some other reviews but I'm ready to see this one!

[@RobMacKendrick]

Thanks for this! Now that I'm 100% QRP, and frequently use monobanders on various bands, I really need an affordable multiband amp for use at home. ~40w forward is ample for me. This one has everything I want, in theory. Nice to have your expert opinion.

[@laverdanick]

Well that’s a first, I actually heard that QSO while testing out a half wave kite antenna. I called Doug after you had signed with him, but the wind dropped and my antenna ended up on the ground. Still at least I know what wind it won’t fly in. Nick G0OQK.

[@Vichardhara303]

Prominent and clear audio super impressive voice ..very nice I liked it ..

[@Gm1vla]

Excellent as always Mat

[@CustomVideoProductionsNYCNJ]

Clean, and well done, with no drama, love it!

[@adi-hg2zt]

He could have called you Rodney I love only fools and horses reminds me of when I was a kid thanks for the laugh.have a great day and all the best to you and your family.

[@TechMindsOfficial]

Thanks Adi !! I find the most mundane things funny lolol

[@eduardogarciamontesdeoca5935]

This little amp works fantastic. However is not intended to heavy usage. The small heath spreader is made out of aluminum and does not do a fantastic job. On the other hand, the output transformer didn’t convinced me. While I was doing FT8 @30w it failed, and I found out that the transformer failed and fried the original transistor. Not a super hard work to replace the faulty transistor and transformer, but definitely it have some details that can be improved. I also tested a MRF9120 on it (got fried because of the transformer issue) and gives 60w with just 1w drive signal. That’s enough to drive my SB201…

[@lpark8]

Great video thanks! Just ordered one on Amazon

[@aureliusprimus]

Fine ! does it also work on 11 meter band ? Regards 😀

[@W4TRI_Ronny]

Would love to see a follow up on the PTT connection. Say for the 817.

[@TechMindsOfficial]

I’m pretty sure this amp comes with a FT817 cable as standard. However, connecting to other radios is really easy, as long as there is a port on the radio which has a PTT line which goes “low” to ground, when the radio is keyed.

[@paulkinas7926]

@@TechMindsOfficial I have run one of these amps for several years now, and it comes with a cable to attach into the FT817 data jack on the back of the rig. Works well with the FT817 when QRP doesn't quite make it... 73 Paul NA9M

[@mscir]

Looking forward to the XPA125B review, esp. the antenna tuning part. Thx.

[@geirha75]

how to attenuate a qrp radio trasmitting 7 w so I can use it with this amp?

[@geofham8332]

Hi, thanks for the test as I am interested in this amp. Again many thanks looking forward to other tests.

[@TubeRadiosRule]

I use one with my Yaesu FT817ND and I love it!

[@TechMindsOfficial]

Great little amps these are!

[@vk2yi81]

I'm curious on what the minimum output of a HL2 is and what the output of the amp would be at that level. I'm really just needing around 10w-15w to drive an tube amp. Thanks

[@frankwc0o]

I use the IC705 with this amp. I noticed yesterday with my 1/4 wave ground plane antenna for 20meters that my IC705 states that the SWR is below 1.5 for 40 meters! I don't believe it. So I tried it and I was talking to someone 30 miles away. Have you noticed that on the IC705, you will read a low SWR on bands that the antenna doesn't support?

[@bwilkins26]

I had this one and it went bad when I tried to key up while connected to a tuner. Don’t run more than 1w with the 817 thru this when connected to a tuner. It doesn’t have protection

[@benc5464]

Love this video! I'm thinking of buying this amp for my QRP rig and I was hoping you or anyone else could explain a little more about the difference between the two power connectors on the back of the amp. I am new to HF (currently studying for my General) and am trying to do all the research I can before building a station. Thanks in advance!

[@merlinonline67]

Mine has started blowing fuses, I have been told that it may be a zener diode?

[@dxscotland5901]

I like the look of the Hermes lite Mat,can you buy them ready built or is it kit only? Thanks Gm4zji Chris

[@TechMindsOfficial]

Hey Chris, there are three parts you need. The main board, the filter board and then the case. Did you see my build video on the HL2? Also, you can get regular updates on stock from the Hermes Lite google group. :) 73

[@dxscotland5901]

@@TechMindsOfficial yes watched the build so think I should manage that ok Mat,I’ll check Hermes Site for availability thanks 👍

[@brucesteele3052]

For me, 5 watts is the point. If I want more power, I will have a radio that delivers adjustable power from 10 to 100 watts.

[@chublez]

Pretty hard to get that for the same cost as adding this little amp to yer existing kits if all you want is to get 30-40w which tbh Is what I often run my 100w rig at for FT8 etc. So this behind say a qdx with a nice efhw would be a pretty rad and very portable and cost effective digital mode toy.

[@languagetruthandlogic3556]

Just what I was thinking! Use a radio designed for the extra power.

[@j204ever5]

What ist the minimum Input Power to drive the MX-P50M?

[@news_internationale2035]

Do you absolutely have to use that PTT connector?

[@SirsenduGhosh1989]

Can you suggest any VHF UHF power amplifier for SDR like Adlam Pluto? This may help us to work satellites or conduct moon bouncing. 73

[@F5VMJ]

Nicely nicely... always look forward to your vids 👍

[@ryanpunter1]

Had my HL2 for a year now, amazing radio. Will look forward to seeing more suitable amplifiers to boost that 5w's before pulling the trigger to purchase one myself. Keep up the great work! Once you've finished doing the hf amplifiers, any chance of looking at transverters for the HL2? A bit spoilt with a FT847 sat next to the HL2.

[@ON8EI]

Hello Peter, did you get the amp for the HL 2?

[@ErnestGWilsonII]

Nicely done! Thank you for making these videos and sharing them with all of us! Question: How much current does the Hermes radio draw and how much does the amplifier draw? You said you were running them both off the same supply at 13.8 volts and I was wondering the current draw of each and the maximum combined as well. I am of course subscribed with notifications turned on and thumbs up! 73 W3GUY

[@merlinonline67]

I've been thinking of getting one to go with my FT-818, its the cable that is putting me to be honest, would like to see how this is set up

[@TechMindsOfficial]

If the 818 is the same as the 817 then there is a cable with it, it just plugs into the back of the 818 and then connects to the PTT cables. Super easy!

[@ONYXRCR73]

Love your channel. Thanks for the time you spend to share on KZbin! I need your help, I have a Herme Lite 2 full kit coming should be here in USA in a bout 4-5 days My plan or wish, is to add a AMP in-line from the Herme Lite 2 to get somewhere around 40-50 Watts then Feed that output into my Ameritron 80B for 800-ish output into my Hexbeam. How or what would you suggest I get to do this. And is there any known issues doing this with two amps. One day I will purchase a nice ANON and this issue will be gone but I want to try this out before moving to that level of expense. You seem to know everything about amps for the Herme lite 2 and would like to thank you for your input to help me out. Million thanks and I hope to work you on the bands, Im in California so a bit harder for us west coast hams to get to UK on a normal day hihi. Steve N6OIX

[@TechMindsOfficial]

Hey Steve! I've tried a few amps with the HL2. The MX-P50 could be used, but I would perform the switching mod, I think @hamradiotube done a video on the modification. I have tested the 125B from Xiegu, which worked well for me. But the best in terms of quality was the HobbyPCB Hardrock 50, but you will need to build it from a kit unless you can find a second hand one. I have never used an amp to driver another amp, but above is my experience :-) Thanks for watching.

[@stridermt2k]

Looking to see your take on this one. Cool in advance.

[@johnluengosalcedo2522]

Hello, congratulations on your videos, I love them What configuration is needed to use it with Hermes Lite 2? Thanks John CE6UBP

[@Linas_LY2H]

Very useful review, thanks! I’m testing now something similar :), the MiniPa50 in combo with my IC-705, so it will be interesting to compare the in/out results. 73! Linas LY2H

[@stevenwright9764]

Any update on the Mini pa50 and 705?

[@Linas_LY2H]

@@stevenwright9764 It's on the way , waiting for better weather conditions to make some field experiments outdoorsy :) 73! Linas LY2H

[@DAVIDGREGORYKERR]

Would it hurt to change the RF power devices out for the proper Motorola Power devices.

[@TechMindsOfficial]

I had also questioned this myself, whether higher power devices could be used. I havnt investigated this yet, but first thoughts are whether or not the other components or even the tracks on the PCB, could handle the extra current.

[@G0ogs]

Also good the intermediate license holders 😏 Dave 😬

[@KC1PSK]

Would this work with a X6100?

[@MarkPentler]

What are the harmonics like? Anyone had one on an analyser?

[@radiotec76]

The manufacturer should have been more honest and advertised the linear amplifier as a 40 watt amplifier. That being said, on the receive side, the S meter will hardly be able to tell 40 watts from 45 watts. It takes an increase of 10 times the output power at the linear amplifier over the input power from the rig to just barely be shy of 2 s units on the S meter on the receive side.

[@alzeNL]

Very nice, whats the current draw like on the amp ? something you could use portable ? great video. 73 2E0FWE

[@TechMindsOfficial]

It’s about 8amps when driving full 5 Watts into it. I would imagine it’s a great portable amp! Cheers!

[@mscir]

Nice Watt meter. Great price.

[@markg6jvy135]

Great video 👍👏👏

[@RajithaPrabath]

Thanks you very much for the valuable video. 73s 4S6RSP

[@TechMindsOfficial]

You’re welcome sir!

[@merlinonline67]

I've done a bit of research and this amp needs a mod if it is to be used without potentially causing damage to the radio, see here: kzbin.info/www/bejne/aXLdiaONp7mYf9E

[@jaimieboy999]

Can i power this with a lithium battery so i can still take it qrp?