[Amps] Parallel Amp Operation

[Glenn McNeil]

Hi Guys,

I'm about to begin the last phase of my 144 / 432 Mhz GS35B Amp 
Project...that is, building a common Power Supply to run both Amps. I'm 
intending to use Ian, G3SEK's Triode Protection Boards....one in each 
Amp. The Power Supply has a 240/2300 vac at 1A Transformer ( 400w PEP 
Max Power in VK ), a 40uf 5kv Oil Filled Cap, Bridge Rectifier with big 
meaty diodes in each leg and Step Start.

As Ian's System uses an HV Enable line, I propose to operate both Amps 
at the same time, but never both keyed at once... i.e HV will be on both 
Amps at the same time, but each Amp has its own individual Filament and 
Bias Supplies.....and run each HV Enable Line to one of those Russian 
Vacuum Relays that are listed on eBay for a reasonable price. So, 
instead of switching the EHT Transformer primary off if a fault 
condition develops, I'll drop off the EHT via the Relay to the faulty 
Amp.I will have a common glitch resisitor in the Power Supply, before 
the Vac Relays. I use a common Station Sequencer that only enables me to 
key up one band at a time.

The primary reason for this line of design is to save a few bucks, and 
more importantly, some room ! I also have future plans, if this initial 
system is a success, of expanding the whole thing to run HF and 50 Mhz 
as well, using the same type of tubes and the same supply...4 Amps off 
of one common EHT Supply.

Can anyone see any impending trouble with this type of design, or any 
reason why you cannot run the G3SEK System in multiple Amps, all using 
the one EHT Supply...with the return - HV line from each Amps G3SEK 
board all tied in a knot at the -HV point in the EHT Supply ? I've been 
staring at the circuits for a few hours trying to see if there are any 
traps for young ( and not so young ) players here..in relation to 
parallel current paths that may upset things. Looking back out of the 
common -HV point in the Power Supply, I will have initially two sets of 
Anode and Grid  Meters essentially in parallel with each other, but only 
ever one set doing anything at any given time. I don't think I can see a 
problem, but other, wiser heads may know otherwise.

Any ideas or comments ?

73
Glenn
VK4TZL





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