OT: K3 and TT QSK amps: credit where credit is due

[DOUGLAS ZWIEBEL]

Well, maybe Al was a cw guy, but the Titan was designed by Dick, K4XU,
which for me, is a lot more meaningful!

If you don't know Dick personally, try his QRZ.com profile:

RF power MOSFET development and applications engineer. 30 years RF
design experience at Ten-Tec, ETO and Harris Broadcast

de Doug KR2Q
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[P.B. Christensen]

> Well, maybe Al was a cw guy, but the Titan was designed by Dick, K4XU,
> which for me, is a lot more meaningful!

I didn't realize that Dick had designed some of the Alpha and Ten Tec amps.
I do know that he is a solid RF engineer with the wherewithal to solve
difficult RF problems when some of the best fail.

Back in my pre-law life, I was Assistant Chief Engineer for RKO Radio's
WFYR-FM in Chicago.  In the mid '80s, a bandpass filter was added to the
output of our Harris FM-25K transmitters at Sears Tower to minimize Tx-to-Tx
IMD interaction between close-spaced stations.  However, the addition of the
filter was causing PA instability under conditions that would otherwise
optimize PA tuning by establishing minimum AM noise content.  Under optimum
PA tuning, the transmitter would become unstable and go into a VSWR fault
condition.

To make a very long story short, while Dick was with Harris, he ended up
adding a line stretcher between the output of the Harris Tx and the BPF.
That solved the instability problem.  The issue was long-standing until Dick
rationalized the effect of the BPF on the wide-Q quarter-wave cavity of the
Harris FM transmitter.

I would take one of his designs any day.

Paul, W9AC

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[Jim Brown-10]

On Fri, 21 Nov 2008 10:10:06 -0500, DOUGLAS ZWIEBEL wrote:

>Well, maybe Al was a cw guy, but the Titan was designed by Dick, K4XU,
>which for me, is a lot more meaningful!

Thanks Doug. The fact that a guy of Dick's quality was working for Ten
Tec is a reflection on Al's priorities and management. Good people hire
good people. The 425 is a nice amp, especially considering when it was
designed and what it cost. Think about it -- nearly a 30-year old design,
lots of them around, working fine, reasonably easy to work on, and
changing hands 30 years later for a decent price. I've got three of them!

73,

Jim K9YC


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