Re: PA question


I think its a good idea to start with the 10 ohm resistor in place.  You can always bypass it.   We probably need to start keeping track of all the modifications for different bands. Ill report in what i find optimal for 6M once I run all of the studies.  

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ


Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois


Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it:

email:  bill@...


On Feb 25, 2017, at 4:45 AM, Hans Summers <hans.summers@...> wrote:

Hi Patrick

I haven't tried the RD15HVF1 myself and tested it's performance in different scenarios. I did hear yesterday from one PA kit constructor who used the RD15HVF1 for a 6m transmitter and is getting 5W output on 6m. I didn't ask if he did the the 10 ohms mod or not. I would think that it is probably good practice to include it. In testing with the IRF510 I found that the 10 ohm resistor is mostly not necessary and does slightly reduce the power output. But at certain frequencies and supply voltages (or I should say, modulator output voltages) there was some instability, that the 10 ohm resistor cured. Hence my recommendation to include it.

73 Hans G0UPL 

On Feb 24, 2017 23:48, <patrick.nairne@...> wrote:

Hello all

I have completed the PA and have installed the RD15HVF1 instead of the supplied IRF510. Is it necessary to carry out the modification involving the 10 ohm resistor when using the RD15HVF1 ?


Patrick M0AFZ

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