开云体育

Hi Robin,

Sadly I dont think I can help on this one. When I trimmed the number of turns on the inductors (L1, L2, L3 and L4) I decided through lack of time to avoid the cut-n-try approach in favour of the measuring the inductors and adjusting turns until they matched the specified values in the manual. It was more labour intensive but I felt it had a better chance of success given my currently limited spare time.

I performed the measure, adjust and re-measure on each inductor and then re-fitted all the inductors into the board in one operation so I did not notice which (if any) of the inductors made the biggest change to the power output. What I can say is that my inductors started off with the specified number of turns but ended up being way-off due (I suspect) to the well documented and notoriously poor sample-to-sample tollerances of this type of core.

If it helps I can tell you how many turns I had to remove from each core...

L1 manual says 25 turns (had to remove 5 turns)
L2 manual says 27 turns (had to remove 4 turns)
L3 manual syas 25 turns (had to remove 5 turns same as L1)
L4 manual says 24 turns (had to remove 5 turns)

As an aside, I rummaged around the shack and found some old (very old, 20 years +) T37-2 cores and wound the specified number of turns as a check to satisfy curiosity as to the s-p-r-e-a-d in core characteristics with cores from different suppliers and of different ages. The result was that in almost all cases the final number of turns required for a given inductance is subject to "tweaking" due to tollerances in the core. Conclusion: they have not got any better over the years Hi.

Hope you enjoy the QCX and look forward to hearing you on-air.

73,s

Des (M0AYF)