Re: Question about 4S Tuner


Jim, N5IB
 

Hi Tim,

Since you're not hearing any peak in background noise or signal when making adjustments, it's probably something in the LC Tee network, rather than in the SWR bridge or indicator circuit.

First question... is there any change in background noise when you switch from "IN" to "OUT" ?

Second... measuring from the top of L1 to ground with an ohm meter, is there essentially a DC short (~ zero ohms) for ***every*** position of SW1 ?

Third... measuring from J1-1 to J2-1 with the SWR bridge "OUT" do you see an open circuit condition ? With the bridge "IN" do you see a few ohms ?

Fourth... do you have any instrument capable of measuring capacitance in the tens to hundred of pF range ? If so, can you check C1 and C2 that they do in fact vary from a couple of tens of pF up to their max of 250 pF

Jim, N5IB

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