To: | [email protected] |
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Subject: | Re: LF: Re: 137.7682kHz QRSS30 beaconing - reports appreciated |
From: | Stefan Schäfer <[email protected]> |
Date: | Thu, 08 Sep 2011 16:28:21 +0200 |
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Roger,If that small heat sink actually remains cold, efficiency must be quite good! Even switching the FET without a drain current causes losses... Since the IRF540 is a 100V device, you have plenty of space for QRO :-) Nice circuit. It shows how easy one can build a LF PA! Not much difference for a 500W type, just the FET has to be changed to a IRFP260N or so... 73, Stefan/DK7FC Am 08.09.2011 15:33, schrieb Roger Lapthorn: Photos of (a) the 137kHz QRSS30 beacon and (b) the 137kHz transverter are on my blog page at http://g3xbm-qrp.blogspot.com/2011/09/lf-kit-improvements.html . Subject to test results, both may be tidied up and boxed later. Otherwise it is back to the bench.The PAs run almost cold, whereas my 50 ohm dummy load is very hot, suggesting very good efficiency from the IRF540 device in each case.73s Roger G3XBM |
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