To: | wlfuqu00@uky.edu, amps@contesting.com |
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Subject: | Re: [Amps] Centurion cooling improvement ideas for AM service |
From: | "Rob Atkinson, K5UJ" <k5uj@hotmail.com> |
Date: | Tue, 31 Aug 2004 13:13:55 +0000 |
List-post: | <mailto:amps@contesting.com> |
Thanks Bill, it sure makes sense to me and is probably one of the selling
points vacuum tube bc xmitter mfrs used. also, they need some headroom
because they go to around 120% positive. Rob/K5UJ From: Bill Fuqua <wlfuqu00@uky.edu> To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>, amps <amps@contesting.com> Subject: Re: [Amps] Centurion cooling improvement ideas for AM service Date: Fri, 27 Aug 2004 15:59:09 -0400 Sometimes that seems to be the case. Figure a transmitter using a 1000 watt Plate input triode class C push-pull amplifier. At 75% efficiency you would have 750 watts output power. But remember your class AB audio amplifier is really running about 60% to 65% efficiency so the same tubes would produce 650 or so watts output which is not much more than what you really need 500 watts. Also, if it is capable of 600 watts the modulator would produce less distortion at the needed 500 watts. And besides if you have a pair of 810s in the RF amplifier why not use 810s in the modulator. That way you would only have to stock 1 power tube type and not 2. 73 Bill wa4lav At 04:27 PM 8/27/2004 +0000, Rob Atkinson, K5UJ wrote: Okay Bill thanks. It seems like I have always seen broadcast tube AM transmitters with modulator tubes that are the equivalent of the rf lineup, i.e. 1 kw out from pair of 3-500s and pair of 3-500s in modulator to provide audio pwr equal to rf carrier and so I thought the audio power had to match the carrier limit for 100% high level plate modulation. _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today - it's FREE! hthttp://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps |
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