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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 2:13 pm 
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Location: Carrollton Georgia
Your memory is dead on. . I changed it out last night. And still the same problem. I post on qrz and here thinking i would have more ideas, but it appears its the same .

Yes there are trimmers and fixed value in parallel for each band. I changed the fixed value , it was a 30pf . Let me ask can these be cleaned with contact cleaner ? Evaporating type? When i did the alignments it did adjust but it appeared to have dead spots and kjerky in areas.

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 3:32 pm 
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Location: Somers, CT
You'd have to spray under the trimmer, to reach the bearing and contact point for the wiper. One other thought: band switch contacts may come into play here. It is odd it would track on other bands (esp. 80 meters) and not track on 40.

Pete

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 5:22 pm 
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Ok, 40 and 80 meters are off. 20 meters is very narrow but is aligned. 10-10 seem to be pretty much spot on. 160 band is off too and to get any tx i have to tighten the trimmer all the was down. I did find i spider behind the trimmers board but didnt change anything. I havd a mind to buy all new trimmer cap boards but then i wouldnt learn anything.

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 5:37 pm 
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Moved this over to the communications forum since there are likely to be more hams with experience working on that rig. I picked up a used Yaesu FT-101 preselector on eBay from a seller who parted one out a few years ago. That seems happen too frequently.

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 9:00 pm 
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Ok, i appriciate all the help. I seem to have the problem cured. T104 was way off, it may have bern when i aligned it with a broken core in T101. Everything aligns up nicely, except 160 meters. It transmitts way above 10 meter band. Trimmer still has to be tighten all the way down to get 10 watts. Not sure what going on .

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sat 08, 2019 9:40 pm 
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I checked the local oscillator on my scope using X10 probe and the closes i can get 300 mv is 900 . It wont adjust any further. I thur the measure function and it gives me vpp and vrms on the screen . But the receiver wont adjust down to .3 volts. , ill take a picture later.

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 Post subject: Re: RF probe for fluke dmm
PostPosted: Jun Sun 16, 2019 2:15 am 
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N5ESE has a classic rf probe, which i modified a littl and it works really well. I used 1/2" copper pipe and put BNC connectors in the end caps. It worked great aligning the crystal frequencies on my yaesu ft 101e. I used it with my vtvm . Proably most have seen this or already have something but it does work well down to about 200 mv .


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