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G6Tanuki · 8th Jul 2019, 2:33 pm

Yes, the impedance-matching is likely to be an issue!

Either use a tuned-circuit with a tapping for the input, or maybe consider using an emitter-follower. Do you know the impedance of the SAW filter the tuner is designed to drive??

See fig.4 here:

https://www.robkalmeijer.nl/techniek...e71/index.html

for an idea though when I've done this for HF-band crystal filters (either homebrew ones using ex-TV crystals or commercial KVG ones) my trick has been to remove what's shown as "Rterm" and then replace what's shown as the two 22K base-bias resistors with a pair of resistors each double the value of Rterm.

8th Jul 2019, 2:33 pm	#6
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: UHF tuner use. Yes, the impedance-matching is likely to be an issue! Either use a tuned-circuit with a tapping for the input, or maybe consider using an emitter-follower. Do you know the impedance of the SAW filter the tuner is designed to drive?? See fig.4 here: https://www.robkalmeijer.nl/techniek...e71/index.html for an idea though when I've done this for HF-band crystal filters (either homebrew ones using ex-TV crystals or commercial KVG ones) my trick has been to remove what's shown as "Rterm" and then replace what's shown as the two 22K base-bias resistors with a pair of resistors each double the value of Rterm.