[ARC5] 6AC7 and 6AB7

[jmfranke at cox.net]

6AB7 tubes were used in the RDO radar countermeasures receiver. 6AC7 tubes were used in the AN/APR-4 radar countermeasures receiver.

John  WA4WDL

---- "J. Forster" <jfor at quikus.com> wrote: 
> They were used in the Rebecca (APN-2) and ASB-5 RADAR for certain.
> 
> -John
> 
> =================
> 
> 
> 
> 
> > On 5 Feb 2013 at 8:23, Ian Wilson wrote:
> >
> >> Where were 6AC7's actually used? They show up regularly in fairly
> >> large numbers in piles of metal octals, etc. My guess is that they
> >> were used as IF amplifiers in radar sets. I don't recall seeing any in
> >> the Surplus Conversion Manual schematics, though, so I wonder when
> >> they were introduced?
> >>
> >> 73, ian K3IMW
> >
> > You are pretty much right about how they were used.
> >
> > They were used in large quantities in the IF stages of WWII VHF FM
> > receivers like the R-19, and in radar receivers, for instance. I think
> > they were
> > first introduced about the same time as the 6AG7 for use in TV receivers,
> > but
> > am not certain.
> >
> > As Carl pointed out, they tend to load the grid input circuits when used
> > as RF
> > amps. unless the connection to the grid is tapped down or up to
> > compensate.
> > This makes their casual use as substitute RF amps not particularly useful.
> >
> > Many hams used to plug them in place of the usual remote cutoff tube,
> > expecting lower noise and higher performance. In many cases, all that
> > would
> > do is turn the RF stage into an oscillator.
> >
> > They were often used like this in BC-348s. I have no idea if this helped
> > with
> > that particular receiver or not. The BC-348 has a 915 KHz IF, so using the
> > 6AC7 wouldn't hurt its image response too much, I suppose
> >
> > However, the 6AC7 makes an excellent low-noise mixer and a good IF amp
> > when the circuit is designed for them. They also make an excellent
> > oscillator.
> >
> > The military used millions of them and NIB versions are still available in
> > bulk.
> >
> > The 6AB7 is far more difficult to find. It is listed in the RCA HB-3 as a
> > "Television Amplifier Pentode" with the same two-condition screen
> > operation
> > as the 6AC7. The 6AB7 has a transconductance of 5000 umhos, while that
> > of the 6AC7 is 9000.
> >
> > Ken W7EKB
> > ______________________________________________________________
> > ARC5 mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/arc5
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:ARC5 at mailman.qth.net
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
> >
> >
> 
> 
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html