[TowerTalk] Do Log-Periodics Stress the Selectivity of
theReceiver?
K7GCO@aol.com
K7GCO@aol.com
Tue, 30 Nov 1999 18:23:10 EST
In a message dated 30.11.99 15:13:31 Pacific Standard Time, K7GCO writes:
<< Dave
I said it was a 5M pre-amp. In those days there was no 6M band --it was
5M. That's above 50 MHz where a 1/4 WL is about 4' of 4" tubing. If and
when I make it for 10M the tubing will be about 8.5' long. Ya got it?
k7gco
<<
K7GCO wrote---
> For some great reading, read the QST's and Radio Mags from the
> 20's & 30's. A 39 QST had an article on a 5M RF Pre-amp with Hi-Q
tank
> circuits. It used a 1/4 WL length of 4" copper tubing and copper
center rod as
> the tank circuit for the grid and plate circuit. This should be very
Hi-Q
> and selective. I picked up on this idea real fast and immediately
> zipped to the conclusion page to see what they would claim for
performance. It
> claimed 7 S-Units gain where 2 were noise and 5 were signal. If true
or close
> to it this needs to be made up which I will do when I get back to SD.
I
> will make these plug in copper tube 1/4 WL tank circuit so I can plug
them
> into the Millen R9er......
Did I totally misunderstand what you are saying, or was the circuit in an
APRIL issue of QST? I think I would have a hard time fitting a 1/4
wavelength of 4" copper tubing into my shack...let alone into any piece
of equipment I have ever seen...I know I don't have the means to wind it
into any kind of a coil...and I probably can't afford that much copper.
When I first read the above, I wondered if you meant to type "...a 1/4 WL
of 1/4"...", but that would still be pretty hard to put into an existing
piece of equipment.
I agree that many AVC circuits need improvement...but boy this idea blew
me away.
73 es gud dx,
-Dave- K9FN
>>
>>
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