[ARC5] 12a6 to wideband coupler

[Henry Mei'l's]

If that 12A6 buffer was coupled as a cathode follower, I did something 
similiar to an 80 meter unit back around 1962 - pretty sure  I found the 
circuit in the CQ Command set manual - also had the advantage that you could 
put a tuned cirucuit across the buffer plate choke and run the stage as a 
multiplier, if you did something with the 1625 output tank - I converted 
mine to PI net -- it was very stable -- used the roller inductor as tank and 
placed a broadcast variable in place of the original variometer-coupled 
tank: - used the original shaft and  gear so that the coupling knob remaind 
a coupling adjuster --still have the original parts I removed - so I could 
restore to original state  - but no longer have that transmitter.Also put a 
potentiometer in for fine adjustmetnt of  PA bias voltage. I keyed just as 
you did --Also found that the right combination of RC constants in the 
cathode keying filer yielded a very pleasant bell-like CW note because of 
the envelope shaping. I also do this on my TCS transmitter.

I agree with you  Ian - simple gear is what I enjoy using most. My rice 
boxes were/are not my style.

73 Henry, OZ1UF




----- Original Message ----- 
From: "Ian Joesph Parkinosn" <cd40105 at yahoo.co.uk>
To: <ARC5 at mailman.qth.net>
Sent: Friday, July 23, 2010 12:10 PM
Subject: [ARC5] 12a6 to wideband coupler


Hi,amateurradio life started back in 1969 with the 2 tubes 1626 and 1625 for 
160 metre operation. No voltage stabilser needed.

About 1975 I got hold of an 80 metre version ARC5 and converted the set 
nearly as a september 1969 ??QST, I fitted a wide band coupler to the buffer 
( 12A6), and cathode keyed one of the 1625 Pa Valves only used 1 valve, no 
chirps or key clicks with a simple capacitor resistor filter.

Had loads of fun with the R4C rx combination, just used an ATU and got a low 
S.W.R. with an end fed wire. I liked what it said in a 73 mag.

.."You don't need an ocean going yatch for a decent afternoons fishing".

73 de ian G3YRQ.





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