Hi Jim,
The fact that the amplifier still works at all suggests that the
amplifier did not get zapped bad enough to kill a tube. I would first
suspect something more sensitive such as a semiconductor in the bias
control circuitry has been damaged. Yes maybe a tube has been damaged,
however before putting in new ones I would be sure that the bias control
circuitry is functioning properly. You don't want to ruin a brand new
tube, and without the right bias you could do just that. How do the grid
and plate currents at zero drive power and full drive power compare to
what they were when the amplifier worked correctly? What about the
exciter? Is it still putting out full power? How about interconnecting
coax cables? Are you sure one of them has not partially failed? Or even
your power indicating device (external RF watt meter or built-in power
indicating function on the amplifier multimeter?) Maybe the amp is still
putting out full power and your watt meter is not reading correctly
after the lightning strike. More details should be ascertained before
dollars expended on new tubes.
DE N6KB
Jim Miller WB5OXQ wrote:
> I have a Centurion about 6 years old that has always made around 1200-1300
> watts on all hf bands except about 1000 on 10 meters. I recently had a
> lightning strike to my fiberglass dual band vhf uhf antenna on a different
> tower from my hf antennas and neither of my hf transceivers were damaged. I
> now find that I can only get about 700 watts on any band driving the amp with
> either transceiver. Could this have damaged the tubes? I don't mind a new
> pair of 3-500's if that will fix the problem. Should I buy the regular
> 3-500z tubes or the zg graphite models. Will I gain anything by using the
> graphite plate tubes? Any mods anyone can recommend that will improve the
> amp performance while I am in there? Suggestions please!
>
> Jim & Ella Miller
> WB5OXQ & KA5EPM
> Abby & Sparky
> Dalmatian Furbabies
> Waco, TX
> _______________________________________________
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> TenTec@contesting.com
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>
>
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