Yaesu FTDX101MP PA finals (VRF150's) testing, replacement, and quiescent bias

Yaesu FTDX101MP PA finals (VRF150's) testing, replacement, and quiescent bias - KJ7E

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Жыл бұрын

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...

Пікірлер: 15

@Ctt61 Жыл бұрын

Really cool stuff. Would have loved to see video of the PA Unit Adjustment. Thanks for posting this!

@dl8zaw 6 ай бұрын

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...

@damonkj7e 6 ай бұрын

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.

@dl8zaw 6 ай бұрын

@@damonkj7e Thanks! I'll try it with no termination...

@g0fvt 11 ай бұрын

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...

@damonkj7e 11 ай бұрын

Running 150+ watts on FT8 is not a problem for this radio as long as the VSWR is below 1.5:1.

@g0fvt 11 ай бұрын

@@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...

@g0fvt 11 ай бұрын

@@damonkj7e mine is back from the dead now, transistors were not ridiculously expensive from Mouser (UK).

@F5PBG 11 ай бұрын

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

@damonkj7e 11 ай бұрын

Correct, however I was in a mode that bypassed VSWR foldback (PA Current ALC calibration).

@_devjatov_ Жыл бұрын

ALC не помогло ? Мощность не скинуло ?

@damonkj7e Жыл бұрын

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.

@_devjatov_ Жыл бұрын

@@damonkj7e большой был разброс токов усилителя мощности с завода по сравнению с сервис мануалом ?