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70 MHz PA for Flex-6700

Peter BaconPeter Bacon Member
If anyone is looking for a 70 MHz PA to go with the 6700, then I would recommend looking at the OZ2M kit http://www.rudius.net/oz2m/70mhz/pmpa.htm It was quite simple to put together and gives me about 20 watts output.  Surprisingly, I have found that if I can hear anyone on 4m then 99% of the time they can hear my 20 watts.  In my first week of operation I have worked 15 DXCC countries on 4m - a lot of fun, and a change from 6m.
73 Peter G3ZSS


  • EA4GLIEA4GLI Salvador Member ✭✭
    edited November 2016
    Thanks for this. I just show it doing a search. Interesting.
    Do we know if there is a non kit version for a 70Mhz amp for the 6000s? 
  • Paul BradbeerPaul Bradbeer Member
    edited June 2016
    I'm also branching out to 4m, Peter. I found a Dutch website (www.fmbroadcastparts.com) with a nice range of 4m modules. Including one with 65w output. I should be getting it by the end of this week....figured I could run it well in its linear region up to 50w. Will post photos when it arrives but it looks a perfect match for my 6500
  • philip.theisphilip.theis Member
    edited June 2016
    Peter, listen for us from the 20-25 of June; we will be operating from HH2 as 4V1G and will have a 7 el beam pointed to EU. Wish we could have taken a Flex, but not ready for power on 4m yet.
    Phil HH2/K3TUF
  • Peter BaconPeter Bacon Member
    edited June 2016
    We will all be listening on 4m with interest!  Only downside is that we have not even had any openings on 6m so far this year across to the Caribbean!  But you never know!  73 Peter G3ZSS
  • philip.theisphilip.theis Member
    edited June 2016
    Openings may have begun. We will beacon on 70.190; listening in between
    This will start June 20 from FK38
  • David G4NRT / Z21NRTDavid G4NRT / Z21NRT Member ✭✭
    edited January 2018
    Interesting discussion fellows!  

    I am awaiting the return of my 25w Spectrum Communications 4m transverter.  I sent it to Tony for rework and re-calibration and it is on the way back to me.  

    Antenna-wise, I have a 4m vertical ring antenna from Nevada which I will be using initially and also a 50MHz/70MHz dual band yogi which I have just received from InnovAntennas and which I need to assemble and mount for SSB and CW.

    David G4NRT
  • edited July 2016

    I have a Kalmus 172F 200W linear amp. The spec. sheet states that It's a 50 dB amp, so if my calculations are correct it needs 0.5 mW drive to get the 200W out. I understand that the transverter TX port on my 6500 outputs 1mW? so that's in the ballpark with some attenuation between the port and the amp.
    I also have a BER 4 Metre amp. that I could **** the PA from, and fit the Kalmus in the case, making use of the substantial heat sink and RF relay switching.
    Can anyone see any problems with this set-up? and are my figures correct?

  • Graham SmithGraham Smith Member
    edited December 2016
    Stewart, the 6500 puts out 35mW from the transverter skt. My FM Broadcast parts linear gives 70 watts out when fed this way.
  • edited July 2016

    Thanks for your reply Graham. Is the output variable or fixed?
    The Kalmus has an attenuator at the input, but I'm unable to read the values of the resistors. I'll remove them and measure.

  • Trevor-EI2GLBTrevor-EI2GLB Member
    edited June 2019
    Sorry for the old thread revival can anyone show some examples how these PA units are connected to the Flex and work, I assume you need a relay to drop it out of the RX loop

  • EA4GLIEA4GLI Salvador Member ✭✭
    edited June 2019
    70mhz out of the xvtr port into the amp. Rx either the same xvtr port or any of the 2 antenna ports.

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