Yes again on your comments below Jim. I use a commercial Taiwanese MeanWell 3.3 kW PF corrected switcher for my 8 x VRF2933 HF S.S. amplifier. It's a very compact unit and runs cool and is EMI / EMC
This replacement bandswitch looks very well made Hsu! It should do well in the marketplace. 73 Leigh VK5KLT --Original Message-- From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Hsu Sent:
Yes, those numbers are about right Peter. On that much larger allowable linear plate swing on the tetrode, that characteristic and efficiency difference is also evident on my valve HiFi amplifier usi
Yes, I too prefer the graphical load line design approach. The old RCA tube publications were great, as were the Mullard/Philips and STC tube guidelines back in the era when tubes ruled the day; and
Hi Bill, A good informative site for practical two-tone based IMD measurement on ham amplifiers is that of Larry W0QE...see his URL below: http://www.w0qe.com/Technical_Topics/imd_testing_of_amplifie
Good comments and analogy here Peter...many homebrew tube amplifier hams (and the occasional commercial amp designer) often deploy inadequate plate choke RF bypassing / decoupling on the B+ line...es
Yes that's correct; the GU84B tube has heater activated getters so running the filament/heater for 24 hours should be fine to burn-in and stabilize the vacuum quality prior to RF amplifier service. Y
For just a small number of extra dollars one can readily find reputable brand and quality built Cornell Dubilier / CDE high-voltage /low ESR / high ripple current rated 105 deg C electrolytic surplus
Excellent figuring Peter! An additional choke and bypass cap is almost essential to prevent deleterious 1.8 MHz RF blow-by into the HV power supply electrolytics. Mind you the HV "glitch" resistor al
Hi Chris, such poking and probing lethal HV power supplies to measure their AC ripple and / or any superimposed RF blow-by leakage is fraught with danger for the unwary. I am fortunate to have an old
John, Had it been 10 years ago, the logical replacement for the 4CX1600B tube was the mil-spec GU-84B with its larger 2500 Watt plate dissipation and prodigious power output capability that would res
Yes, certain doorknob caps are fine for QRO filters, at least at HF. I have used low-cost Russian mil-surplus NOS ceramic NPO doorknob capacitors in LPF circuits for QRO solid-state amplifiers at the
Yes; excellent practical suggestion Peter...this will work well and the Duroid substrate is easy to guillotine to precise dimensions to get the readily calculable target C values. Leigh VK5KLT Rogers
Yes considering the risk of dire consequences for expensive failure and repairs it would be wise to take precautions and guard against exceeding the Quadra's narrow rated spec for AC mains input volt
Well Ian that's still a ridiculous situation is it not? One would hope then that things go bang in the warranty period when the manufacturer has to wear the consequences of their design folly... Leig
Yes, surprising indeed Peter. I'm not sure about UK consumer law, but here in Australia the equipment vendor at the point of retail purchase has an overarching obligation to market goods that are "fi
Manfred, you have made some most excellent riposte comments here...bravo! I concur with them, and your pragmatic no-nonsense engineering design philosophical outlook. Your savvy and insightful posts
Indeed Peter. And high plate bias current and associated low efficiency is part and parcel of achieving high linearity and low intermod from AB1 tetrodes. Low plate idle current and low IMD are mutua
Hi Paul, These proposed EBS techniques you advocate using a short delay line on the audio would work a treat...completely benign bias transitioning operation that yields a useful dissipation / heat r
Yes Jim, the maximum impact bang of course comes from PTT operation... Leigh VK5KLT Indeed Peter. And high plate bias current and associated low efficiency is part and parcel of achieving high linear