Hello everyone, I would like to trace the cause of not having RF output on the PA of the uBITX v4, under the load of 50 Ohms resistive. Could someone post the waveforms on the oscilloscope at the diff

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Hi Ben, If the bitx 40 is still available and you're willing to post to the uk i will reimburse you for any costs.regards Dsve.,

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Hi Ben I would be interested in your V3 if it is still available. I would gladly e-transfer, in US dollars, your costs for shipping as it would entail shipping to Canada. E-mail adr here is bevtedstan

#bitx20 #v3

Hi All -- Bob responded very quickly. Radios are claimed. Thank you.

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I would love to have your item(s). Mike

#bitx20 #v3

Hi All, Being that my day job is pretending to be a design engineer, I go through stages of ham radio building at home. Sometimes (usually) I don't want to come home and fight the same problems I do a

#bitx20 #v3

Thanks , will try replacing the TDA 2222 and if that doesn't work them will use the LM386 amp

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For scratchy audio on a V3, could be in the TDA2822 amp. An easy way to check this is to take the VOL-M wire from the volume control pot, detach that wire from the TDA2822 pin 7, then connect that wir

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The audio is very scratchy on my Ubitx V3. What needs to be done.

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It took me a while to understand it. Basically, as designed, the transistor base to emitter junction And the couple and capacitor form a half wave rectifier power supply. Charging up the coupling capa

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Gordon, I had read your argument long ago and for some reason I don't remember this point about the C80 charging up. Good point. Jerry, KE7ER

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All of the receiver front end protection that I found on the net used two diodes as I had them configured. The worst case I believe is that the second diode would be redundant and the best would provi

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I really didn’t use mine an awful lot after I installed one diode, but I never ever had a Q90 go bad. My previous discussion of the failure mode suggested that it was reverse voltage, as that coupling

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I think two diodes should work fine. Gordon is saying that one diode might be sufficient, since the base-emitter junction of Q90 can work as the second diode. He could be right. Though that 2n3904 bas

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I was going off of Evan Hand's mod (https://groups.io/g/BITX20/message/83186) which has two diodes, one opposite the other, across two of the pins on K1.

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The only diode needed on Q90 is one to prevent reverse voltage damage.

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oh, and I removed the diodes.

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I'll check all that, thanks. As for test equipment, I have both a DMM and an old oscilloscope.

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Kit, I would expect a transmission of 15W a short distance away to create a very strong signal in an unshielded uBitx. Perhaps you also have a problem in receive, but for now I will assume that is not

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I haven't dug into this in depth, but I did test receive last night. Pumping 15 W into my loop with a borrowed Kenwood TS-2000 I was able to (faintly) hear my transmission in a dummy load. I suppose I

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