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Thanks again Immo!! The input wires going through the binocular core were bare copper with not insulation, short possible?? The windings were insulated wire.? I will rebuild it using your

hi Bill, some possibilities: a) if a short winding is on the core (short in itself) the core gets high impedance! Perhaps some of the the windings were short (over the edges of the core) and to

So essentially the input side tests, ok?? Now I am really confused.? I was hoping the short was there.??Bill

That all looks to be like it should. :-)

I just got all the windings pulled out of T1 and T2 and didn't find any issues. What did you think about my continuity readings? Bill

hi Bill, I used 0.5mm enameled copper wire. #24AWG also #26AWG may suit. As inner winding I used a piece of RG174 whose shielding is connected at one side to ground. For making it easy to wind, I used

I desoldered as you picture instructed. *No continuity between Input and ground now.* *There is* *continuity between input and output.* *The windings on the T1 and T2 have no continuity with the solid

Bill, If not already tried, if you terminate the ATU Ant connector with a 50 Ohm dummyload, what VSWR does your Trx show on transmit? If your Trx doesn’t have vswr, put one in between your trx and

Will do.Bill

resolder these ends, so ground stays on the secondary windings

Thanks Dave!! ?Got a lot of investigating to do. If nothing else I am sure learning a lot about the ATU-100 and troubleshooting it. Bill

Hi Bill, At DC, since the SWR bridge will look like a short circuit to ground, then all contacts of relay S8 will also look like a short to ground. A simplified diagram is shown below. Perhaps, if

Thanks for the update. ?I will try that.Bill

after desoldering one end of both secondaries only the wire through the binocular can make an unwanted short to primary signal path.

hi Bill, last idea: desolder on end of both secondary windings of the bridge. So no longer DC shorts through the windings are possible. Then you can test again for shorts on the signal path. only the

So my finding on Relay S8 having a short to ground on all the contacts regardless of being powered up or not is suspect?Bill

hi Dave, you are so right! But at a point I began to turn in a circle… Sure on DC the bridge shorts the signal path… Sorry Bill! But the RF measuring shows a short on signal path. 73, Immo

Hi Immo, Bill, At DC the resistance between the centre pin of the RF connector to ground will measure as a short circuit (as per Immo’s diagram). From an AC (MHz) point of view the bridge will look

Hello Bill, The bridge is DC shorted to ground. Not AC! Use a nanoVNA to measure the input impedance Goo luck, Paulo Em dom., 10 de nov. de 2024 às 14:14, Bill via groups.io

May have found it.? Relay S8 has continuity between Ground and the Common, NC and NO contacts when it is powered up and not powered up.? I have spare relays and will replace it.Bill