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Old 24th May 2020, 8:14 pm   #100
crackle
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Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
Default Re: Superstar 6900N V6 - Fault with SSB mode

Quote:
Originally Posted by SiriusHardware View Post

Can you reinstate bias supply link J3 ONLY, key the radio in SSB TX with zero audio input, roger beep off, and observe and record the current drawn in SSB TX mode?
Hmm that didnt go too well, with J3 fitted and all the other conditions met, it looked like 18 amps on the PSU and the alarm went off DC lo, it all happened so quick.

I think I may have to do a bit more checking around the TIP36 and take the final mosfets out because I did the same test on FM and the same conditions applied, about 12 amps.

So does it look now like the original fault was bias issues causing self oscillation in the OP pair.

I think I will take out the link L10 to the OP pair and try and check some of the voltages from the TIP36.
And desolder the legs on the IRF520 finals ready to test.

What is the best way to test them with out removing from the heat sink, can a DMM be used?

Mike

Mike

Last edited by crackle; 24th May 2020 at 8:23 pm.
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