I have been hearing claims at the local flea markets here in South Africa that a single 4-250A valve is capable of between 800 - 900 watts in ham band amplifier application. Now I have used these mys
W. F. -- With its max peak emission of 1.3a and a 4500v anode supply using g-g config., my guess is that a 4-250A has enough stuff to do 1000w-out PEP in SSB service provided that it is tuned up with
Wynand & Rich, In an impractical application, a Kahn envelope elimination and restoration amplifier, the 4-250A is capable of a smidge over 2KW PEP just as in plate modulated AM operation. The max pl
was the plate/anode white hot? R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/l
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 2 Jul 2006 12:02:18 +0200 (CEST)
In Class C, they're rated at 900 watts input. The filament structure is the same as the 3-500, so I'd expect similar performance, just less plate dissipation. For speech without a processor, you'd pr
Thanks Peter. That is what I usually aim at when I construct ... about a kW out but I have gone to considerable trouble and expense acquiring spectrum analyzer/communication analyzer and other test e
<snip> Hi Rich, Not if the tube is operated at 90% efficiency. You may want to review Kahn's Envelope Restoration technique in the Proceedings of the IRE, Vol. 40, July 1952, pp 803-806 Some further
There is an intersting article in QEX this month where the author describes a 2KW PEP 80/40 meter output amplifier using 4 TV sweeps tubes with a switchmode power supply providing envelope restoratio
This is great! I can finally achieve my goal of getting 1 KW CW from my favorite tube, the 813. It does complicate bandswitching, though. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco ________
Reading the emails I have not seen one that states the obvious. The 4-250A is electrically identical to the 4-400A except for plate dissipation. They just added fins to the 4-250A to make the 4-400A.
That RCA rig was a single-frequency affair and that circuit is a bitch to tune. I wouldn't touch it for ham use unless I wanted to park it on, say, 3885 kHz. Been there. - Jim WB6BLD ________________
And if the 4-250A is operated at 110% efficiency in high humidity, frost will form on the envelope during lengthy transmissions? Seriously, Marv, after looking at the constant-current curves, I don't
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 10:06:29 +0200 (CEST)
Wynand - and this applies generally, I think - more than 400W so the last think we need is the regulator having to enforce the regulations< We need to bear in mind the spurious emission requirements
Most interesting discussion. Peter wrote: "On the other hand, if in a 10kHz wide band starting 6.75 kHz away, you aren't down 50dB, then you're somewhat antisocial anyway." It appears, from i.a. SM5B
Most interesting discussion. Peter wrote: "On the other hand, if in a 10kHz wide band starting 6.75 kHz away, you aren't down 50dB, then you're somewhat antisocial anyway." It appears, from i.a. SM5B
I think based on the work by SM5BSZ i think a good standard to aim for in ham transmitters would be the FCC's Part 80 maritime IMD mask standard. It requires 3rd order products to be down 30 db as re
At VHF the ETSI specs. I've been working to lately have changed from the old MPT ones and there's an absolute -36dBm on harmonics and spurious up to 1GHz, regardless of tx power level. At 100W it's a
I think based on the work by SM5BSZ i think a good standard to aim for in ham transmitters would be the FCC's Part 80 maritime IMD mask standard. It requires 3rd order products to be down 30 db as re
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 3 Jul 2006 15:37:19 +0200 (CEST)
bandwidth limit. If you are below such a signal level at 3kHz on SSB, you can be doing anything you want in that 3kHz.< You need a bit more of a spectral mask than just a bandwidth limit to ensure th
With a 3kHz limit, AM would be virtually banned. Should AM have 2x the limit of SSB? R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amp