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In that case I can see why it blew
up!!
g3kev
----- Original Message -----
Sent: Tuesday, September 07, 2010 7:17
PM
Subject: Re: LF: 137.5kHz WSPR Tuesday
evening - reports appreciated
Just hit a bit of a snag and blew up my (last) IRF510 PA
because of totally inadequate heatsink. So, I'm on 137.5kHz WSPR but only with
about 1W from the simpler PA at present, so ERP low uWs. I need to get
some heatsink and more FETs!
Any reports (now less likely) still
appreciated.
[Mal - it started out as a Class E design attempt but
hadn't been optimised, so I guess this counts as class D.
]
73s
Roger G3XBM
On 7 September 2010 17:34, Roger Lapthorn <[email protected]>
wrote:
My
137.5kHz WSPR TX transverter is now working fine, so I'll be on-air
with WSPR tonight (Sept 7th) from 5.30pm - 11pm UK time.
After my success on QRSS3 with G3XIZ I'm hopeful he'll now decode my
WSPR signal tonight, assuming Chris can take a listen. If anyone else
within, say, 100km of Burwell, Cambs JO02dg cares to take a look for the
WSPR beacon (running around 35% TX time) I'd be most grateful.
Not sure if anyone else has had this problem, but I was using
the small 16mm 3C90 cores (cream colour) as the PA bifilar output
transformer and I had all sorts of issues with the darn thing overheating
and even one cracking. I replaced this with a choke wound on a T106-2 core
and made the output network work in class D/E and now everything is working
very predictably. The larger diameter 3C90 cores seem fine in the step-down
transformer matching the "in the air" loop.
The WSPR beacon is now
going ON.....
73s
Roger G3XBM
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM
GQRP 1678 ISWL G11088
--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM GQRP
1678 ISWL G11088
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