[ARC5] Backwave

[millerke6f at aol.com]

One of the schemes that was  covered in some of the CQ publications was separating the cathode connection and the ECO tank with a nominal 0.01 ufd disk cap and then keying that cathode via a 2.5 mHy choke along with the 1625 cathodes.   I used this scheme back in the early 1960s with an 80 meter command set with great success.  I also ran the 1625s with 150 ohm carbon resistor in their cathodes to kind of get them running a more linear region.  With a regulated 105 vdc on the oscillator and 450 VDC on the 1625s and 250 on the 1625 screens I got around 15-20 watts ( light bulb watt meter) out of the unit with excellent keying and full break in in using an untuned tube T/R switch (6AH6 if memory serves).  On Field day 1962 I worked all lower 48 states on the bottom end of 80 meters using a DAQ receiver.  The DAQ weighted over 125 lbs and dwarfed the tiny command set transmitter.

Cheers


Bob, KE6F


-----Original Message-----
From: WA5CAB--- via ARC5 <arc5 at mailman.qth.net>
To: arc5 <arc5 at mailman.qth.net>
Sent: Sun, Oct 25, 2015 9:05 pm
Subject: Re: [ARC5] Backwave


Larger sets that don't work this way (relays) generally run fixed bias

supplies to the rest of the exciter and the final to cut them off key up.  And

the oscillator is simply keyed.

In a message dated 10/25/2015 20:41:19 PM
Central Daylight Time, 
arc5 at mailman.qth.net writes: 
> Well I had no idea
what a backwave was, so I had to look it up. There 
> isn't much out there
either! 
> Anyway, it seems that one of the accepted solutions is a "grid
blocking" 
> circuit to kill the spurious signal.
> The original relay
clackty-clack which keys the osc and finals 
> simultaneously works pretty well
if you have a stable supply.My curiosity was piqued 
> when I saw the original
design, so I wanted to try it "their way". No modern 
> post WWII stuff works
that way, so it was "new to me" in that sense, just 
> like backwaves. This
group has been an education for me.

Robert & Susan Downs - Houston
wa5cab
dot com (Web Store)
MVPA
9480
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