Dear Mal, LF
Group,
No ? it is possible
to design these transformers with a small air gap, but there does not appear
to be a great advantage to doing so because the required number of turns
increases, increasing the ?copper? losses and offsetting any reduction in
core loss. There is always a quite large gap in the original LOPT ? often
this is produced by inserting plastic film spacers between the core halves.
These, and any glue, should be removed so that the core halves fit together
perfectly. Sometimes the gap is produced by machining the core legs to
unequal lengths, in which case you can?t really use the core in this
application.
Cheers, Jim
Moritz
73 de
M0BMU
Tnx Jim for the
info. My LOPT cores have equal leg length, and in the past I have removed
the plastic spacers when present and they work well. This appears to be what
u have done ie no gap.
Thanks to all the
others as well for their info.
I am working on the
project at present. I notice up to a few hundred watts there never seems to
be a problem with heat, explosions etc but when aiming for
an o/put of 1 kw things are more critical, 2 cores needed, more
robust wire on the transformer. My present project uses 2 x
26A/500V Fets on each leg ie total 4. I am hoping to get up
to about 100v and see what happens. So far I have managed 800w out at
40v/22amps but above this things get tricky, pa getting hot and the
winding on the o/p transformer getting warm. The design is similar to
YXM/MRF with a few refinements.
I happen to have
these fets so I am trying them out, lets hope they
survive !!!!!!!!
All suggestions
welcome. In the past I have used low voltage high current up to 60Amps and
all has been well but going to a higher voltage and lower current
the PA performs differently even though this would appear a better
approach, using the above Fets.
I should really use
my Decca and save myself a lot of trouble with home built gear, but then
there is not the same satisfaction when working the DX
!!!!!!
73 De
Mal/G3KEV
-----Original
Message-----
From:
[email protected]
[mailto:[email protected]] On Behalf Of hamilton mal
Sent: 31 March 2005 13:36
To:
[email protected]
Subject: LF: TX Cores
Jim ur mod to the G0MRF using a
TV line output transformer. Did u leave a gap between the cores or not
?
