OpenBCM V1.06 (Linux)

Packet Radio Mailbox

ED1ZAC

[C.D.G. OpenBCM]

 Login: GUEST





  
G8MNY  > TECH     25.06.19 11:30l 51 Lines 2022 Bytes #8 (0) @ WW
BID : 9746_GB7CIP
Read: GUEST
Subj: Using 2 HF PAs
Path: ED1ZAC<ED1ZAC<GB7CIP
Sent: 190625/0926Z @:GB7CIP.#32.GBR.EURO #:9746 [Caterham Surrey GBR] $:9746_GB
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
              Ŀ
        ĴHF                                Ŀ     Ŀ
Ŀ__/. ĴPAĿ                Ŀ_________HF_____HF Ŀ
HF RF :  Ĵ1     Ŀ        HF RF  _____PA  ___PAĴATU
   ____/.    \__ATU          ___ )Ĵ1   Ĵ2  
RigPTT: :  Ŀ            RigPTT       
   ______/..HF                    _____  
ALC: :...PA                ALC  
        :.....2 
              
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...

      ڴ<PA1 PTT     Test PTT interaction by keying up
 PTTĴ                 Tx + PA & seeing if connecting the
      <PA2 PTT     unused PA has any affect on Tx/Tx.
                        Add diodes if there is any affect.

      ڴ>PA1 ALC     Test ALC interaction by setting Tx
 ALCĴ                 + PA to 100W & adding the turned
      >PA2 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


Read previous mail | Read next mail


 27.06.2019 12:17:30lGo Back Go up