[Milsurplus] TCS Receiver: "More than one way to skin..."

[David Stinson]

Neil:
I read your letter while out with the wife and got to thinking 
about it.  When the B+ rises above the breakdown on the zener, 
the diode goes into conduction.  So any RF rides on the 
conduction, just like diode switching of RF in modern, plastic 
toy radios.  The cap is not needed.  I did scope it as-is and 
there was no oscillation, but your point is well taken.  Now 
moot, since it's not required and I removed it from the circuit. 
The thing one learns with a hot soldering iron. ;-)
73 Dave AB5S

----- Original Message ----- 
From: "AKLDGUY ." <neilb0627 at gmail.com>
Subject: Re: [Milsurplus] TCS Receiver: "More than one way to 
skin..."


>I see two problems with the 0.047 capacitor across the zener.
> The first is that at the instant the B+ is turned on, V2 is 
> subjected
> to the full 220V B+,
> since the capacitor is essentially a dead short until charging 
> gets underway.
> That high voltage may have a detrimental effect on V2's life.
>
> The second is that a capacitor placed across a zener or voltage
> regulator tube may
> create a relaxation oscillator if the timing constants happen 
> to favour it.