To: | "amps@contesting.com" <amps@contesting.com> |
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Subject: | Re: [Amps] Ten-Tec Centurion |
From: | Will Matney <craxd1@ezwv.com> |
Date: | Thu, 11 Nov 2004 14:22:40 -0500 |
List-post: | <mailto:amps@contesting.com> |
Ian put forth a very good point. If the amp could be switched to
transmit mode by RF sensing, it would be illegal under U.S. law and
could not be produced. This holds true for any amps yet or until the
rules are changed. To me, the amp should not be able to be keyed without
the switching jack connected to the transceiver. I could not find a
schematic for the Centurion on the internet to download to look at the
circuit. If someone knows where one is, let me know. The only way I have ever seen an amp run by itself is by self-oscillation caused by parasitics or no bias as Bill pointed out. One must remember, Tom said this problem only occurred when using the one transceiver to drive the amp, correct me if I'm wrong on this. If so, that would kill the idea about the bias being bad as it would do it with any transceiver wouldn't it? Next, if it's a parasitic oscillation, what is the difference between the one transceiver and the others that could trigger it? About the only hair brained idea I could think of is that the one transceiver had more drive going in the input jack, that something was sensing this, and maybe putting a small amount of RF on the cathodes of the tubes making them conduct, thus starting up an oscillation. This may, or may not, be from parasitics though. Without the relays pulled in, the RF should be bypassed from the cathodes and put across the load or antenna. I dont reckon that amp would have a faulty reed relay where the contacts are welded together allowing RF on the cathodes? The only other thing I could think of would be two unshielded conductors being side by side, one having the RF from the transceiver on it, and the other going to the cathodes. This would act like a strip line type wattmeter pickup, and put a small amount of RF on the cathodes. If it were over the tune C having a pitted plate allowing the B+ to arc, it would happen with any transceiver used. For an RF arc, the amp would have to be running for the RF to be across the tank circuit. Anyhow, before I can comment further, I'd have to see a schematic on this amp to see how the RF is being switched around. Best & 73's Will Matney Ian White, G3SEK wrote: R. Measures wrote:
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