[sdiy] More transistor woes (possibly off topic, but...)

Elain Klopke functionofform at gmail.com
Fri Jun 8 11:31:27 CEST 2012


On Thu, Jun 7, 2012 at 7:32 AM, Harry Bissell <harrybissell at wowway.com> wrote:
> quick ideas...
>
> high gain circuits (as a rule) MUST be in a metal box to provide RF shielding.

I thankfully have a metal box I can put the next one in. Metal box: check.

> The layout may be sub-optimal. You must avoid LOOPS of wire which form inductors that can
> change the circuit behavior greatly (including acting as antenna for receive and transmit)

There was a loop or two in the original circuit.... but that's what I
get for using perf-board at really early in the morning...

> Building a circuit with a ground plane can help a lot. You can take a piece of copper-clad
> board and sandwich it beneath your unit.
>
> Maybe 100pF cap across the input jack to ground to try and shunt RF...

These I will try... need to get the 100pF caps.

> What station are you receiving... what frequency range and how far from the source are you ?

I honestly don't know, a) I have been in this state for a bit under a
year now, b) I don't have a (working) radio, c) never did listen to
the radio very much (can't stand the commercials) and d) everything I
was picking up was in Spanish... which I don't speak.

I'm sure the metal box and the ground plane will help greatly a any rate...



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