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IZ3LSV

[San Dona' di P. JN]

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G8MNY  > TECH     11.11.19 11:16l 51 Lines 2022 Bytes #999 (0) @ WW
BID : 29550_GB7CIP
Read: GUEST
Subj: Using 2 HF PAs
Path: IZ3LSV<IR2UBX<DB0RES<ON0AR<GB7CIP
Sent: 191111/1014Z @:GB7CIP.#32.GBR.EURO #:29550 [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!


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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