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

[@Ctt61]

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

[@n4shxradio]

I hope you could answer this -2 questions 1. how did you terminate J6001 and J6007 to a 50-Ohm Resistor what cables where used? 2. For the Final Stage Idling current how did you connect a DC Ammeter between the Power Supply and the FTDX101MP?

[@damonkj7e]

For the PA Bias, the terminations is necessary, though I did buy some small jumpers to that plug into the PCB sockets that extended to BNCs and can connect to BNC dummy load terminations. Ive done it both ways and the terminations are not necessary. I inserted a current meter between the 50v supply line, and nulled he non TX current to get the bias measurement.

[@n4shxradio]

@damonkj7e thank you for answering, this is the 2nd time my finals went bad. After yaesu repaired it, I've decided to do it on my own, I live in the Philippines and sending it to Japan again to get repaired is out of the question, because it's super expensive. You replying and creating this video is super helpful. This means a lot. 73 and Mabuhay De 4E1FLD | N4SHX

[@n4shxradio]

@@damonkj7e Thank you for replying, this video is really helpful, for context this is the 2nd time the finals went bad on this radio, the first time, I sent it Japan for repair, and it was super expensive, to ship back and forth to the Philippines and on top of that I also had to pay for the repair cost. I had to wait 6 months to get it everything sorted out. So going through he same process is a no-go for me this time. This video is really helpful. 73 and Mabuhay De N4SHX | 4E1FLD

[@dl8zaw]

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]

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]

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

[@g0fvt]

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]

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

[@g0fvt]

@@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]

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

[@elanpaim33]

the big question is why ? it look many do have this issue look like poor quality parts

[@damonkj7e]

I addressed this in the video. It was my fault.

[@_devjatov_]

ALC не помогло ? Мощность не скинуло ?

[@damonkj7e]

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_]

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

[@F5PBG]

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]

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