[HBR] Need advise: protection for my only 1600 kcs xfmr

[Peter Bertini]

Regarding using a shunt feed B+ for the IFTs;  rather than look for an
outrageously large value RFC, considering making the RFC parallel
resonant at the IF frequency instead.  Pete

On Mon, May 17, 2010 at 8:03 AM, C Eus <catman351 at gmail.com> wrote:

> All:
> I reviewed just about all the HBR circuits.  One of my concerns is that B+
> to the mixer tubes and IF amps runs directly through my precious set of IF
> transformers. I wouldn't want some unfortunate short to take out any of
> these transformers.
>
> Currently (pardon the pun) the 1600 Kcs IF amp is fed through the IF
> transformer through the primary winding and then through an 1800 ohm
> resistor, which is filtered by a .02 uF cap.  Ditto with the 100 kcs
> stages.
>
> Is it possible to feed signal output from the plate of the mixer/IF amp
> tubes to the next stage using a plate blocking capacitor and then feeding,
> directly, the plates of the mixer/amp tubes using the 1800 ohm resistor and
> placing the .02 uF bypass cap on the bottom end of the resistor nearer to
> the B+ source?
>
> If this is a "yes,"  what would be the value for such a cap?  As to the 100
> kcs side of the house, I suspect the value for such a plate blocking
> capacitor will be much lower.
>
> I don't have the background to determine these values (other than good old
> X=1/(2*pi*F*C) and then try to chose the value showing the lowest impedence
> so the tube "sees" the impedence of the transformers instead.
>
> Any advice will be most helpful. Thanks. Cal, n6KYR/4.
> ______________________________________________________________
> HBR mailing list
> Home: http://mailman.qth.net/mailman/listinfo/hbr
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:HBR at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>