Yaesu FTDX101MP PA finals (VRF150's) testing, replacement, and quiescent bias - KJ7E
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- čas přidán 3. 08. 2023
- Made a mistake and transmitted full power CW on 160m in to what was thought to be dummy load when I was in fact it was a 20m yagi. This caused one of the VRF150's to develop a drain to gate short. The short caused the 50v supply to shutdown, this caused the radio to go into a boot loop with how the power supply stages during startup. The finals are easy to replace if you have proper de-soldering equipment. You must re-bias the PA and should perform the ALC and Output Power alignment in the service manual after replacement.
Edit, see this follow up video where I retest the TX IMD with the new finals: • Yaesu FTDX-101MP Two T... - Věda a technologie
Really cool stuff. Would have loved to see video of the PA Unit Adjustment. Thanks for posting this!
Thanks Damon, very helpful for me because I have the same problem 😞. How do you terminate J6007 with 50 Ohm for adjustment? What sort of plug is this. I cannot find anything that fits...
I did find the connector on a jumper to a BNC, I dont recall where from. However, I found no reason to terminate J6007 since no RF is being generated. I've made the adjustments both ways, J6007 terminated and without, no difference.
@@damonkj7e Thanks! I'll try it with no termination...
It is not normal that this failure to occur. The Yaesu FTdx101 should have gone to safety like it happens on the FT2000D. 🤔
Thanks for the feedback anyway.
73's de Ludovic - F5PBG
Correct, however I was in a mode that bypassed VSWR foldback (PA Current ALC calibration).
Sadly I have the same radio with the same rebooting symptom. I am tempted to repair it myself than wait months for a warranty repair. I think my attitude is similar despite having the radio such a short time, it worked when I got it but doesn't now...I had set a ceiling of 50w in the menu but subsequently did a reset so MIGHT have transmitted full power on FT8...
Running 150+ watts on FT8 is not a problem for this radio as long as the VSWR is below 1.5:1.
@@damonkj7e I have just got the new transistors, will fit them tomorrow. I will be careful not to repeat this, I feel it was me that blew it up not the makers fault. Though I have ragged my older Yaesus for years...
@@damonkj7e mine is back from the dead now, transistors were not ridiculously expensive from Mouser (UK).
ALC не помогло ? Мощность не скинуло ?
The fault was not with the radio, I had created a unique set of circumstances and caused this problem myself. Its a long story, but involved a mode where the VSWR protection was disabled.
@@damonkj7e большой был разброс токов усилителя мощности с завода по сравнению с сервис мануалом ?