I have used the split flyback cores with good success here for my 500W amp
design which is very similar to the G0MRF design and uses James' ideas
regarding the current feed configuration. The trick is lapping the
connecting surfaces on a flat surface with 600grit paper. Click the core
back together and wrap it it fibre tape or something similar and wind your
coils... You may need to experiment with a few different 'brands' of
'street ferrite' before you find one that is man enough...
----- Original Message -----
From: "Gary - G4WGT" <[email protected]>
To: "LF (Rsgb LF Group)" <[email protected]>
Cc: "Jim Moritz (M0BMU)" <[email protected]>
Sent: Wednesday, December 22, 2004 12:44 PM
Subject: LF: M0BMU mods for G0MRF 300 W Tx
Hi Jim & LF,
I am about to carry out the M0BMU current-fed mods for the G0MRF 300 watt
class D Tx.
I have salvaged several cores from monitor flyback/line O/P transformers &
they all have an air/di-electric gap on the round leg of the core. Is this
OK or should I search for one with no gap?
Also reference the home-made "litz" wire, there are 2 descriptions during
the course of the e-mails covering the subject ie: 3 groups of 4x 0.3 mm
& on the diagram 12 strands of 0.3mm ecw. Which is best/correct & how best
to make it up ie: parallel or twisted strands/groups?
If anyone is using the mod how well is it performing.
I have increased the heat sink & airflow cooling.
I have also upgraded the power supply to 40 volts - 12.5 Amps after my
recent (under-rated) power supply failure.
Regards & Thanks in anticipation.
Gary - G4WGT
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