Hello,
New to this arena and just trying to learn!
I am working on a grant that I bought on ebay, was trying to change the final to an ERF-2030+ because the output on their mod (MRF477) was only 9 watts peak, no matter what. Now with the ERF-2030+ it's only 6 watts peak. I was following guide: https://www.worldwidedx.com/threads/mosfet-conversions-for-upd858-and-mb8719-boards.95853/ which had links to cbtricks that had bogus info on the companion part as per https://www.worldwidedx.com/threads...ors-in-the-drawing-and-the-correction.157713/ and I smoked a L39 as a result (had another grant around so borrowed that to replace it). Once i got the biasing right, it seemed okay, keys up and swings on transmit.
Here's the problem:
I was trying to check the voltage at gate and noticed that it would start at like 3.4 and drop rapidly according to my multimeter. I tried different parts of the radio and noticed that it was like that just about anywhere I tried to test positive voltage.
I suspect a bad voltage regulator, but is there anything else that might cause this symptom?
It's hard to tell if the voltage is right on the gate if it isn't stable.
I tried the other grant and the voltage was stable.
I swapped the two VRs not realize how static sensitive they might be and now both radios do the same behavior (oops).
I'll have to wear my wrist strap when I get VRs back in (are they really that sensitive?)
I'm also going to try a different multimeter, maybe mine has a low battery or something.
New to this arena and just trying to learn!
I am working on a grant that I bought on ebay, was trying to change the final to an ERF-2030+ because the output on their mod (MRF477) was only 9 watts peak, no matter what. Now with the ERF-2030+ it's only 6 watts peak. I was following guide: https://www.worldwidedx.com/threads/mosfet-conversions-for-upd858-and-mb8719-boards.95853/ which had links to cbtricks that had bogus info on the companion part as per https://www.worldwidedx.com/threads...ors-in-the-drawing-and-the-correction.157713/ and I smoked a L39 as a result (had another grant around so borrowed that to replace it). Once i got the biasing right, it seemed okay, keys up and swings on transmit.
Here's the problem:
I was trying to check the voltage at gate and noticed that it would start at like 3.4 and drop rapidly according to my multimeter. I tried different parts of the radio and noticed that it was like that just about anywhere I tried to test positive voltage.
I suspect a bad voltage regulator, but is there anything else that might cause this symptom?
It's hard to tell if the voltage is right on the gate if it isn't stable.
I tried the other grant and the voltage was stable.
I swapped the two VRs not realize how static sensitive they might be and now both radios do the same behavior (oops).
I'll have to wear my wrist strap when I get VRs back in (are they really that sensitive?)
I'm also going to try a different multimeter, maybe mine has a low battery or something.