That's right Bob, complex indeed. Such linearization and intermodulation distortion correction techniques are not the panacea they might first seem; their practical implementation in ham-radio gear i
Yes fully agreed Tom; my comment here had presupposed the use of a decent exciter! Amongst the poor and mediocre rigs there are some good ones in the commercial transceiver marketplace. Leigh VK5KLT
Ian, I'm sure you or I and a few others would willing criticise the sad state of poor to middling IMD performance in ham-radio Tx equipment in meaningful clinically objective technical reviews, but n
Before doing that Don they first need to rope the inimitable savvy wise owl Rich Measures AG6K into the troop. That dynamic trio ham amps road show would play to packed houses! Perhaps have Tom W8JI
Yes indeed Mike, that's the reality with these tubes. I like to think we can mitigate at least some of this tube life degradation through soft-start circuitry. My favourite means that has great merit
Yes those GE CL-60 NTC inrush limiting thermistors are helpful albeit still yield a fairly fast rise time constant in the filament voltage. The far gentler slow 3 to 4 second ramp up from the Triac c
Hi Chris, See the ON Semiconductor TDA1085C Data Sheet / App Note...all the needed info' is succinctly contained there. Leigh --Original Message-- From: Amps [mailto:amps-bounces@contesting.com] On B
Dick, there's no need to wait for such innovations in RF power semiconductors as such a long awaited low cost S.S. 1.5 kW HF amp can be economically homebrewed using a readily available multiplicity
Ah now Peter, those esoteric distortion correction linearization features will unfortunately take a considerable time for us to see filter down to the solid-state QRO amplifier systems used in the ha
A good place to start Jerry is having a look at the eBay store of Baruch Zilbershatz, 4Z4RB and some of his neat ideas and ham radio market targeted products for QRO HF amplifier pallets. The underly
Larry, the RF power MOSFETS to which I refer here are the VRF2933 devices from Microsemi. Sometimes one can find surplus and NOS ST Micro SD2933 FETS on eBay at low prices. 4 of these rugged 300 Watt
Dick, such reproducible cookbook reference designs will inevitably appear in the ARRL Handbook or a QEX article one day; already a capable 250 Watt SS amp with decent specs was published in a recent
Larry, the Microsemi VRF2933 has a 170 Volt VDD breakdown voltage and 648 Watt power dissipation, and when operated with a 48 V rail there's plenty of safety headroom for potentially damaging high vo
Yes, that's right Don. With a 9:1 xfmr the device load-line would be such that one will never achieve the potential power output capability of 4 x VRF2933 devices...it will flatten / max out at fewer
In answer to your question Jim, my favourite RF power MOSFET today for HF linear SSB amplifier use is the VRF2933 devices from Microsemi. They have a VDD drain breakdown rating of 170V which means op
That's right Alex. However my primary concern expressed in my original email was truncated...I would not consider schemes that directly rectify the mains to provide the DC supply rail to a QRO MOSFET
Well Alex an amateur / ham could consider doing such an abominable thing in a home brew project, but directly rectifying the AC mains would never pass regulatory approval for commercial equipment sal
I can in principle concur with your 3 salient points here Manfred. However, as I said in a recent post an amateur / ham could consider doing such an abominable thing in a one-off homebrew project; bu
Yes all that you mention below is correct Jim. That's why I commented in an earlier post that an individual QRO amp builder would get away with doing this questionable 3 kW power supply realization t
...or rather than conjecture one could simply ask the savvy RF application engineers at Microsemi whose role and raison d'être it is to ensure their MOSFET RF power products are properly and optimall