[Milsurplus] Pi- Matching Network: When?

[DeWitt Clay]

I agree-before the 1950s the only use of the pi network i've seen was for simple low power portable transmitters to get a good match to whatever antenna could be strung up in a hurry. I remember seeing  a commercial aircraft xtmr design in RADIO that used a pi network to couple the oscillator stage to the final in order to get better coupling and more grid drive on the higher frequencies. That reminds me of the coupling arrangement used in the heathkit DX-100. A few other 30s-40s published rig designs did feature pi networks from single ended finals to meet various load requirements/feedlines/antennas. It looks like it just took some time for them to catch on in an era of link coupled push-pull input and output tank circuits.
73, DeWitt  N4QNX
 

________________________________
From: C.Whitaker <whitaker at pa.net>
To: milsurplus at mailman.qth.net 
Sent: Wednesday, February 8, 2012 3:14 PM
Subject: Re: [Milsurplus] Pi- Matching Network: When?

de WB2CPN
Are you asking about ham radios, or are you asking when
it was first used in any radios.  The Pi network has been
around since day one.  Before coax was practical, there
were only two ways to feed the transmitting antenna.  Either
balanced line, or a single wire.  Both needed L and C for
frequency adjustment, (Tuning), so the Pi was one of the
few ways to do it.
Looking back at a recent (?) use of the Pi, look at the BC-375
or BC-191 transmitters which predated WWII.  In the early '50's
my Stancor 203-A, (10 Mtrs only), had a Pi output.  The antenna
on the '52 Kaiser was a 102 inch (?) whip.
73  Clete
++++++++++++++++++++++++++++++++




On 2/7/2012 8:49 PM, David Stinson wrote:
> Anyone have any idea when the Pi output matching
> network appeared?
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