Re: RD16HHF1 power curve flattening...some

K9HZ <bill@...>

Oh yeah, one more thing…  Those RD16HHF1s should draw about 500ma per part (1A total) to put them nicely into the class AB2 operating band for SSB.


I guess we better all get our heads together and write this up and a concerted effort so others can do it too…


I also ordered a pair of RD70HHF1s tonight to try as an add-in amplifier board at some point.  While these parts are not exactly spirit QRP,  I do like the idea of having 100W available when I want it… maybe with the flip of a switch.



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email:  bill@...



From: [] On Behalf Of John
Sent: Tuesday, March 20, 2018 10:39 PM
Subject: Re: [BITX20] RD16HHF1 power curve flattening...some


Impressive, Bill.

I just tried 180pf across the primary of the output transformer, as opposed to the 33pf I had initially and as you mentioned from your simulations before it raises the power lower down to the point where I don't have the dip at 21Mhz anymore. With RV1 at 60%, 13,8V supply I get 22W at 80M, 20 at 40M, then tapering down to 12W at 15M then flat up to 10M. 

So I have wound down my RV1 to get 9 to 10W on the higher frequencies and I get 18-16W on the lower ones. As I wanted. I am now happy with the power curve, especially when compared to the initial one with the IRF510s (17W to less than 2W from memory).

73, John (VK2ETA)


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