Tony,
I built a clone of the 400W version many years ago, just adapted the FET's (IRFP350's) and the output transformer as I wanted to run it off a 56V PSU I had available. Further extended the LPF with an extra L-C stage (although
it works fine with the original LPF) and added a zobel network (as in the 1kW version).
Never had a FET blown, even not when transmitting without antenna ot with a shortcircuit in the coax. Maybe also thanks to the 14A current limiter in the PSU.
In 2008 I adapted it to 500kHz, just replaced the output tranformer (the double U core recycled from a TV HV worked fine on 136 but got very hot on 500) and of course the LPF.
73, Rik ON7YD - OR7T
Thanks for that Chris.
I have the 2nd edition LF Today and the DF3LP is now on p69 and was one that I was looking at, so I'll steer clear.
Shame there's no more G0MRF kits.
Tony, EI8JK.
----- Original Message -----
Sent: Tuesday, June 22, 2010 1:37 PM
Subject: LF: Re: RE: Re: 137 Revival
Hello Tony,
I tried the TX in 'LF Today', 'A Beginners Transmitter', p6 of the first edition and had nothing but trouble, blowing numerous FETs. E-mailed the author DF3LP several times, but he never replied. Watch out for errors in the
circuits in this book!
73,
Chris, G4AYT, Whitstable, Kent.
----- Original Message -----
Sent: Tuesday, June 22, 2010 1:12 PM
Subject: LF: RE: Re: 137 Revival
Hi Tony
Mal transmits reliably and doesn’t suffer fools if that helps!!?? J
There are some good designs in LF today
Dr. James Cowburn G7NKS
E
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I fully intend to be QRV on 137 by the winter.
On that note, can anyone recommend a reliable foolproof transmitter that uses easily available components ?
----- Original Message -----
Sent: Tuesday, June 22, 2010 8:26 AM
How about a 137 kcs Revival, much more interesting than 500, which is more like 160 metres.
CW, QRSCW, Invisible Ros etc
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