[ARC5] Backwave

[Dennis]

I run the osc in my T-22 continuously and key the PA cathodes via a transistor.  The back wave is fairly strong in the receiver but exceeding week as transmitted.  Key down the osc pulls down about 2 KHz.  Because I spot the rig key down into a dummy load, the osc runs 2 KHz above the transmitting/listening freq. so a decent IF filter or notch eliminates the potential self QRM.  On 80M the pull would be less (1 KHz?).  Osc and PA screens are regulated so minimal classical chirp.  One cannot hear the very fast 2 KHz pull in the home receiver or at a local friend's house.

Dennis AE6C

Sent from my iPhone

> On Oct 25, 2015, at 7:52 PM, Ian Wilson <ianmwilson73 at gmail.com> wrote:
> 
> The amount of radiated RF (with the PA stage turned firmly off) should be
> very small - especially since the ARC-5 TX 1625 stages are neutralized.
> 
> 73, ian K3IMW
> 
>> On Sun, Oct 25, 2015 at 7:07 PM, Bill Cromwell <wrcromwell at gmail.com> wrote:
>> 
>> Hi,
>> 
>> My own thoughts on moving the VFO off from your operating frequency is
>> that you would be moving onto somebody else's frequency and causing QRM. If
>> it's enough of a problem that somebody else complained about your backwave
>> then it's serious enough to not push it onto yet somebody else.
>> 
>> I like (and use) grid blocking. It can be managed by transistors - easily
>> done and easily reversed to restore museum quality.
>> 
>> 73,
>> 
>> Bill  KU8H
>> 
>> 
>> 
>>> On 10/25/2015 09:40 PM, J Mcvey via ARC5 wrote:
>>> 
>>> 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.
>> 
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