Schematics?
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Howdo. When you say you resoldered the leads, was that the leads on to PCB, or taking the top off the module and resoldering internally? I had a problem with a VHF PA that turned out to be a bad solder connection on an inductor. DC one side of inductor leg one side of PCB, but not the other. It was a bad connection to copper.? On Tue, 12 Jul 2022 at 12:59, Max Donoghue <ve3tmt@...> wrote: Hi Andrew, |
开云体育Ah That Kingston, not the one 12 miles from me here in Hampshire ! ? This should help, check the drive and the VCO locking they do drift out of lock ? 73 ? Andrew ? ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue ? Hi Andrew, |
开云体育Trace the signal paths, to the TX PA ? From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue ? Thank you Andrew, will do. |
开云体育Ah in that case, buy one of the those small software defined Spectrum analysers, and a few SMA adapters so you can put a scoop probe on it! Look at the single input on the VHF side the UHF will or should be a similar level! ? 73 ? ? ? ? Andrew ? From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue ? I don't have a lot of test gear. Multimeter, small portable scope from Amazon and a NanoVNA. |
开云体育No That is a network analyser, as it has reflection ports and through ports, it is not a spectrum analyser, they are different. ? 73 ? Andrew ? From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue ? Looks about the same as what I have... |
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Do you have a vhf/uhf handheld? Use on same frequency, with a carefully positioned screwdriver tip on the input of the driver block. Will give a rough idea if you have drive to module. By going on the output of module, you should be able to see if? it is working. On Tue, 12 Jul 2022 at 14:53, Andrew Lenton <a@...> wrote:
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A very quick look at diagram,? you should have? 8 volts tx on UHF, pin 1 of J4007 You should have some voltage, less than 8, on Pin 2 of the module.? You should have 13.8 on pin 3 of the module, and RF out on pin 4. Check with handheld at varying distance/without antenna to see if it is amplifying. Check what voltages you have on base and collector of final transistor, Q4006. Should be around 0.65 on base SSB tx, and 13.8 on collector. On Tue, 12 Jul 2022 at 16:01, Max Donoghue <ve3tmt@...> wrote: Yes I can hear the UHF signal quite well on my handheld. But no output power shows on the 847's meter. This is probably the pre-drive signal I'm picking up. |
开云体育You need to know the level, however, that sound relativity good news, The PA block may be obsolete, but tricky to test with limited equipment ? 73 ? Andrew ? From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue ? Yes I can hear the UHF signal quite well on my handheld. But no output power shows on the 847's meter. This is probably the pre-drive signal I'm picking up. |
开云体育Also put an amp meter in series with TPH and 4003 and 4004, that is what it is for, run around 10 Watts and see that to current ?is, at 50 Watts I would expect 10 -12 Amps depending on efficiency! ? 73 ? Andrew ? ? From: [email protected] [mailto:[email protected]] On Behalf Of Andy Bosworth ? A very quick look at diagram,? ? ? ? ? On Tue, 12 Jul 2022 at 16:01, Max Donoghue <ve3tmt@...> wrote:
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Ok, this is strange.? I am struggling to see how you can have 0.7 volts base, 13 volts collector, but no current. That makes no sense. Time to get a bit creative, and enlist the help of your wife. Try the signal in, signal out test with her using the handheld to RX at a greater distance. Then do the same for the base and collector of the final transistor. There's another couple of things to check, I may be insulting you here, but what is PSU TX current on 2 metres, and 70 cms? Are you just going off the meter on radio, or have you actually verified with a power meter and dummy load that no juice is going out, or are you just relying on the meter on radio? On Tue, 12 Jul 2022 at 23:28, Max Donoghue <ve3tmt@...> wrote: Hi Andy, |
Andrew Lenton
Andy Bosworth
