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vk3pa
207 Posts |
 Posted - 01 Oct 2007 : 23:44:21
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It all started with a rebuild of a 4/1000a Amp
Well this is a story of how "QUASAR" was Born.
Having acquired a few bit for a 4/1000a amp up comes a sub chassie for a pair of 4CX1000a's complete with blower, constant voltage filament transformer. Then from the junck box a 3kv @2amp ht t/former,some modern oil filled 10mfd filter caps @ 10kv..Then a couple off Vacuum variable caps 500pf @10kv es 1000pf @5kv ..
Well wot was one to do with a box of "goodies " like this?
So this is the start to my 160m amp.
I think it's like owning a "FERRARI 599 GTB FIORANO" goes like stink " but " we can only drive it to 110 k's on some roads in Victoria Hi..
So from now on I will place more about this Amp as time goes by..
The amp will be run a pair of 4CX1000A's in AB1 with 3Kv on the Plate es 325 v on the screen.. The Amp is Grid driven with the Screen above ground (some amp builders of this tube run the Screen at gnd es the cathode at -325v wrt the Screen at gnd, gud for vhf amps), will have tuned input..es mono band for 160m
Control boards are F1FRV for HV es Screen protection plus metering ciruits es G3ESK Tetrode boards for Screen supply etc..Heaters es Blower will run for 5 min after switch off..
The amp is made up of 4 main sub assemble.. the top is metering, next the rf section,then the control es Screen /Bias supply es on the bottom is the HV section.
Screen and lv supply
Blower chamber
Tune and DC ht decoupling
RF deck front panel 4CX1000A x 2 160m
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vk3pa
207 Posts |
Posted - 02 Oct 2007 : 00:35:58
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QUASAR (or -Z-). n. (Astron.)
very remote,very luminous source of strong radio waves. |
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vk3pa
207 Posts |
Posted - 10 Oct 2007 : 08:25:23
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The HV es metering is done with "F1FRV" ciruit http://f1frv.free.fr which covers HV safety es metering. es goto Tetrode linear amplifier boards es hv -power supply.. Tu Dominique
Screen supply boards are "GM3SEK"style, with regulated 325 v for screen ..
HT 3kv is full wave bridge using stick diodes
pt# D80HL SILEC ES 2X 10MFD 10KV OIL FILLED CAPS in parrell..
Bias supply is Zener regulated with seperate supplys for each tube..
All wiring is done in Teflon coated wire..
Main chassie floors es front (19 inch rack) panels are 6mm aluminium, all side es cover plates are from 2mm alloy sheet..All panels are screwed together using 20mm x 3mm alloy angle |
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zs2cx
5 Posts |
Posted - 12 May 2010 : 15:51:27
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hey allan
looks good.look i am using 4cx1000a's as well.
would like to see your circuit of tank.
one more thing,i have a 4cx1000a amp passive fed
grid2 327v grid1 -60v ht 4kv.
all is well with this one except on tx ht drops immidiately from 4 to 3kv,,mmmm
jeez,man i measured hv caps, 2 bleeders 100k ohm, one bleeder measures 74k ohm (when idle for 5 minutes)
instead of 100k 130watt each.
power drops with ht and current
any guesses or advice.?
johan
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ZS2CX
"Get the fire in the wire,or get the wire up higher" |
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zs2cx
5 Posts |
Posted - 12 May 2010 : 16:03:49
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| one more thing 4kv 2amp |
ZS2CX
"Get the fire in the wire,or get the wire up higher" |
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how "QUASAR" was Born
