Re: IC7000 no HF Transmit
开云体育This is a very hard radio to work on, as you cannot easily get to the PA board the way it is mounted and soldered into the pa driver board ? I would remove the PA board, replace L305, for starters while it is out you can inspect the components one by one. ? This unit does not lend itself to test and measurements, as all you can do is prod the rear. ? All 12V HF PA stages have an impedance in the milli Ohms 0.4 to ?0.6 ohms, as it draws 20A, or so, the output transformer has to match 0.6 Ohms ?to a 50 Ohm, so it needs to step up the voltage. ? The problem is it would be nice to lift L306 and put your Watt meter in there, but you have to rip the PA board out then put it back together to make the measurement, so impractical ? To protect the PA the is a coupler to control power and to protect the PA against hi SWR, however, if no power is getting past the coupler you will have full power 24/7 ? There could be a fault here: ? ? But only you can trace, so measure i/p to L305, you will get a voltage, the out put will be higher at 100 Watts 50 Ohm the voltage will be 70.7V RMS, so PTP on a scope 200V if you are not getting this on the O/P then move back to the I/P you should get 13.8 V ?to 40V PTP. I have one of these in bits working before I box it back together I will make some measurements and send back to you. as the PA in not loaded with 50 OHM, the voltage can rise too high You need to set a voltage on Ref or FOR to knock the power back to a few Watts then you can uses CW and safely trace you signal. ? ? KR ? Andrew G8UUG ? ? ? -----Original Message----- ? This is a very hard radio to work on, as you can not easily get to the PA board the way it is soldered into the pa driver. ? I would remove the PA board, replace L305, for starters while it is out you can inspect the components one by one. ? This unit does not lend itself to test and measurements, as all you can do is prod the rear. ? All HF PA stages have an impedance in the mOhms .1 .2 ohms as thet6drsw 20A, the out put transformer has to match .1 of an ohm to 50, so it needs to step up the voltage. ? KR ? Andrew ? I have a wiring unit, I can make some measurements for you ? ?Get BlueMail for Android ? ? On 26 Jan 2025, 01:32, at 01:32, "Tommy Wooten via groups.io" <kf4rwg@...> wrote: >Bob, Thanks for the encouragement >? >I have considered all of the suggestions for troubleshooting the >problem I have with the IC7000.? I have tried to trace the HF RF path >with an oscilloscope from where the signal comes through the cable from >the main board to the PA board.? I have traced the signal and inspect >all components through to the output at ant1.? The signal seems to >loose its punch where the PA FETs combine into the L305 transformer.? >The bias setting of the PA FETs seem to be correct.? After the signal >reaches the rx/rx relay it passes through the selected HPF where it >reaches ant1.? The resulting signal is only a few milliwatts.? I have >tried to keep the setting in SSB and I see modulation when speaking >into the microphone. >I know it is difficult to troubleshoot the issue remotely but I >appreciate any and all ideas. >Thanks >Tommy. KF4RWG >? >? >? >On Sat, Jan 25, 2025 at 6:31?PM Bob via groups.io <W4JFABob= >[email protected]> wrote: >? >> Well this is #30 then. That's OK because when the rest of us have >this >> problem we'll appreciate every one of these replies. >> Keep on writin' you guys. >> Bob W4JFA >>? >> On Thu, Jan 23, 2025 at 4:40?PM Geoff via groups.io <vk3zgw= >> [email protected]> wrote: >>? >>> Forgive me if this has been mentioned before but as this is the 29th >>> reply I haven't gone back and read everything. >>>? >>> I always go first to where the effect of a fault is obvious without >any >>> ambiguity, in this case the rf output ie Ant 1 connector, working >back to >>> eliminate ALL the stages involved, including in this case the SO32 >jack. >>>? >>> Good luck. >>>? >>> Geoff >>> VK3ZGW >>>? >>>? >>? >>? >? >? >? ? ? ? ? |
Andrew Lenton