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G8MNY > TECH 12.08.24 09:00l 52 Lines 2080 Bytes #999 (0) @ WW
BID : 13490_GB7CIP
Read: GUEST
Subj: Using 2 HF PAs
Path: IZ3LSV<I0OJJ<GB7CIP
Sent: 240812/0700Z @:GB7CIP.#32.GBR.EURO #:13490 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW
By G8MNY (New Aug 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
At an 8 day Ham Summer Camp I needed to use 1 of 2 HF PAs for /P. One was a
500W Transistor PA floated on a large battery that allowed just a small petrol
650W generator to keep the batteries topped up, & the other was a Valve Amp
used in the colder nights & that needed much bigger generators (2.3 / 7kW).
I looked at the 2 possible connection systems...
FULLY SWITCHED SERIES RF & TEED CONTROL LINES
ÚÄÄ¿
ÚÄÄÄÄÄ´HF³ ÚÄÄ¿ ÚÄÄ¿
ÚÄÄÄ¿__/. ÚÄÄÄ´PAÃÄ¿ ÚÄÄÄ¿_________³HF³_____³HF³ ÚÄÄÄ¿
³HF ³RF : ³ ÚÄ´1 ³ ³ ÚÄÄÄ¿ ³HF ³RF _____³PA³ ___³PAÃÄ´ATUÃÄ
³ ³____/. ³ ÀÄÄÙ \__³ATUÃÄ ³ ³___³ ÚÄ)Ä´1 ³ ³ ÚÄ´2 ³ ÀÄÄÄÙ
³Rig³PTT: : ³ ÚÄÄ¿ ³ ÀÄÄÄÙ ³Rig³PTT ³ ³ ÀÄÄÙ ³ ³ ÀÄÄÙ
³ ³______/..³HF³ ³ ³ ³_____³ ÀÄÄÄÄÄÄÙ ³
ÀÄÄÄÙALC: :...³PAÃÄÙ ÀÄÄÄÙALC ÀÄÄÄÄÄÄÄÄÄÄÙ
:.....³2 ³
ÀÄÄÙ
The switched system is complex, unless relays are used.
The series & teed system assumes PA2 can handle PA1 Tx power in through mode!
Steering diodes my be needed to isolate the powered off PA from affecting PTT &
ALC lines...
Ú´<ÃÄÄPA1 PTT Test PTT interaction by keying up
PTTÄÄ´ Tx + PA & seeing if connecting the
À´<ÃÄÄPA2 PTT unused PA has any affect on Tx/Tx.
Add diodes if there is any affect.
Ú´>ÃÄÄPA1 ALC Test ALC interaction by setting Tx
ALCÄÄ´ + PA to 100W & adding the turned
À´>ÃÄÄPA2 ALC off PA. I found no power change so
steering diodes were not needed.
Of course NEVER enable both PAs together! However the ALCs will work overtime
if you accidenty do!
See my Tech bul "T500 M 12V 500W HF Linear", "PTT line for Drake L-4B PA", &
"ALC line for Drake L-4B PA".
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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