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ZL1ABS > HELP 08.08.07 04:33l 31 Lines 1396 Bytes #999 (0) @ WW
BID : E20818ZL1ABS
Read: GUEST
Subj: Re: MAGNUM FOUR TRANSVERTER
Path: DB0FHN<DB0MRW<DK0WUE<DB0RES<ON0AR<ZL2BAU<ZL1AB
Sent: 070808/0122Z @:ZL1AB.#06.NZL.OC #:64485 [AUCKLAND] FBB7.00i $:E20818ZL1AB
From: ZL1ABS@ZL1AB.#06.NZL.OC
To : HELP@WW
Hi Martin,
I agree, a QQVO6/40 will not stand 900 Volts on the plates. According to
my trusty copy of the ARRL handbook 1978, a QQV06/40 or 829 tube/valve can
run with 600 Volts on the plates. The max plate voltage is 750 Volts DC.
Making your own plate supply need not be difficult.
For example there can be a supply of used 230:230 Volt isolating
transformers at the local auction house or pawn shop (local builder or
DIYer down on his luck pawns his tools etc). Two such transformers with
secondaries in series will give 460 VAC RMS at an Ampere or two (more than
enough for a QQV06/40). Hugely better than using old radio RX
transformers. When bridge rectified & capacitively filtered the HT is
bound to be in the range of 550 to 650 Volts DC. The screen supply can be
done with a dropper resistor or regulator tubes per accepted practise in
the RSGB/ARRL/Mullard handbook. The filament/heater supply could come from
the FT101Z
It's been a while since I owned some PYE base station 2m Transmitters that
had QQV06/40 valves in the output. I have an unfinished homebrew 2m
transmitter with a QQE03/12 6360 tube/valve in the final. The PA was good,
just problems getting things to FM properly in the 8 MHz Oscillator &
enough drive for the multipliers. I went to homebrew solid state gear &
had more success back in 1978.
73 de Michael ZL1ABS
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