[Lowfer] New bench testing of PA output filter

Tue, 03 Sep 2002 13:39:51 -0400

John,

>Retune the antenna?

Sure enough did.... and often. When the Q is about 200 just a sneeeeez will 
throw the tuning way off. What is the efficiency with your filtered setup?

Jay: I haven't seen our 'jump effect' lately (this is where the loop current 
jumps down to a lower value when the generator is carefully tuned through 
resonance). I suspended the loop simulator coil 6" above the bench with a 
string and this seems to have done the trick. Must have been some kind of 
electromechanical feedback. Has anyone else seen this weird effect?

Bill

>
>----- Original Message -----
>From: "Bill Ashlock" <[email protected]>
>To: <[email protected]>
>Sent: Tuesday, September 03, 2002 11:29
>Subject: [Lowfer] New bench testing of PA output filter
>
>
> > Mike and all TX loop enthusiasts,
> >
> > You may be interested in knowing that when I insert the 63uh-1.8n-63uh
> > filter (IE: the Lyle filter) between my final and the loop stepdown
> > transformer I loose at least 25% of the loop current for a constant 1W 
>of
> > input power. I have tried different types of cores and 
>inductance/capacity
> > ratios but the results are similar. Without the filter the total
>efficiency
> > is about 95% and those little MPS6602/52s run as cool as cucumbers. I
>can't
> > seem to make the Psice model agree with these results, however.
> >
> > Bill
> >
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