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LF: Re: RE: Re: Re: RE: Re: 137 Revival

To: <[email protected]>
Subject: LF: Re: RE: Re: Re: RE: Re: 137 Revival
From: "mal hamilton" <[email protected]>
Date: Tue, 22 Jun 2010 16:29:50 +0100
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]>,<[email protected]> <[email protected]>
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My 500 Kcs class E TX uses a LOPT and does not get warm generating sufficient RF for 10W erp
----- Original Message -----
Sent: Tuesday, June 22, 2010 3:39 PM
Subject: LF: RE: Re: Re: RE: Re: 137 Revival

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

Van: [email protected] [[email protected]] namens Tony Baldwin [[email protected]]
Verzonden: dinsdag 22 juni 2010 15:57
Aan: [email protected]
Onderwerp: LF: Re: Re: RE: Re: 137 Revival

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 -----
From: Chris
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!
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 [email protected]


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From: [email protected] [mailto:[email protected]] On Behalf Of Tony Baldwin
Sent: 22 June 2010 11:49
To: [email protected]
Subject: LF: Re: 137 Revival


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 ?


Tony, EI8JK.


----- Original Message -----

From: mal hamilton

To: rsgb

Sent: Tuesday, June 22, 2010 8:26 AM

Subject: LF: 137 Revival



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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