Hi Jim, A quiescent power dissipation of circa 1.1 kW in an amplifier is insane; an energy wasteful desk-top blast furnace! Such a design also places undue stress on the tube(s) and reduced service l
That's right Peter; horses for courses / no free lunches concisely sums up the tube comparison quite well. The choice is largely a personal preference one with diehard aficionados in both camps. If h
Good point Peter. That higher ZSAC is completely subsumed and absorbed into the total plate current when the amp is producing RF output. An EBS controlled amp provides its best efficacy in standard P
It's a pity vendors of solid-state QRO amplifiers don't offer purchasers an accompanying low-cost insurance policy to cover them against the inevitable day when the finals blow up for whatever reason
I agree Rob; a fraction of that massive HV PS capacitance would create an unperceivable difference in the Tx performance and signal at a distant Rx station :-) Leigh VK5KLT --Original Message-- From:
Hi Jim, There are two aspects to consider here; the static and dynamic voltage regulation, and the amount of ripple on the B+ plate supply. In CW and SSB amplifier service the keyed and syllabic fluc
Yes indeed Dave; linearity will be lost if the B+ plate supply varies due to excess ripple superimposed on the DC. The degree of that loss depends on whether the tube is operating in Class C, AB2, AB
Yes indeed Peter, 3-phase HV power supplies are very nice from several points of view. However, the discussion here started out in the context of a traditional single-phase scenario with a simple res
Fully agreed Carl. Cheers, Leigh VK5KLT ________________________________________ From: ham_amplifiers@yahoogroups.com [mailto:ham_amplifiers@yahoogroups.com] On Behalf Of Carl Sent: Friday, 11 May 20
All good points Ron. In seriously HV broadcast Tx systems damaging arcs are an important design consideration and reason to restrict stored energy. However, the discussion here started out in the con
N.B. should be 6X not 3X the AC frequency as wrongly stated below. Leigh ________________________________________ From: ham_amplifiers@yahoogroups.com [mailto:ham_amplifiers@yahoogroups.com] On Behal
Hi Gary, The GU74B tube has a rated maximum screen dissipation of 15W, and a typical operating screen current of circa 20 to 30 mA @ 350 Volts, equating to less than 10 Watts. Under normal amplifier
Hi Jim, You've made a good summary below; it's indeed a fruitless exercise to attempt to improve the PF of a big SSB linear RF tube amplifier. At least your utility Watt-hour meter is billing you for
Yes Peter, you won't go astray if you take your clues from what the leading commercial and professional vendors of the tube amplifier era did in their power supply designs; all based on pragmatic tim
All good points Carl. When I use my RF speech processor the Po and Ip come up to almost static values and represent a roughly steady load on the HV power supply. As for residual ripple, tube amps hav
Hi Jim, I agree with most of your comments here; just to clarify I was referring to the context of Peter's older boat anchor amp equipment and the constraints in power supply design and component acc
Nah Jim; although 60 uF is plenty adequate to achieve more than ample regulation and low ripple on the B+ plate supply, a 116 uF reservoir capacitance is at the upper limit of what I reckon is sensib
Well Lou, if by way of comparison one considers the current cost of a fully optioned Ameritron AL-82 amp for circa $3000, then perhaps a fully mod'd L4B in such apparently pristine condition for the
Charles, I reckon the best thing you can do to ensure tube longevity in your amplifier is check with an accurate RMS calibrated AC voltmeter to see whether or not the filament voltage measured right