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Old October 4th 06, 05:06 AM posted to rec.radio.amateur.homebrew
David David is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 19
Default Trouble matching SA605 input at 434 MHz

Mark,

Yes, that's the circuit I am having trouble with.

Regards

David

MarkAren wrote:
David,

http://www.geocities.com/markaren10/misc/SA605.gif

You had this in mind ??

-Mark.

David wrote:
I am having trouble matching to the input of a SA605 at 434 MHz.

If I apply a sig gen directly to pin 1 via a 1n cap I get around - 95Bm
sensitivity. I then add my match and the sensitivity drops more than
10dB. I am expecting 10dB increase in sensitivity when input is matched
correctly.

First I tried matching to 800R as per input impedance listed in the
Philips APP note. I then noticed most applications matched to 1k5.

My current circuit is C-Tap (33pF to ground and series 5p6 to inductor).
18.5nH inductor (Q = 100) across input pins 1 and 2.
10n decoupling cap from pin 2 to ground.

Any help much appreciated.

Regards

David