----- Original Message -----
Sent: Sunday, October 18, 2009 2:49
PM
Subject: LF: Re: AF Amps at 136
Chris
Do not use audio amps for RF. Build a
class D or E amp and operate trouble free. Audio amps were tried by some in
the early days but never worked properly.
Read the horror stories of yesteryears about
using audio amps for RF applications. Buckets of burnt out
FETS.
73 De Mal/g3kev
----- Original Message -----
Sent: Sunday, October 18, 2009 2:13
PM
Subject: LF: AF Amps at 136
Hi All,
Just started constructing TX for 136kHz,
noticed Maplin do a Velleman audio PA kit that is rated at 200W (100W RMS
into 4R). OK there's no mains transformer or heat sink, but reckon it's
good value at £14.99. Point is the specs also say the minus
3db frequency response is 3Hz / 200kHz.
The RSGB books 'LF Today' refer to using
audio amps as PAs at 136 with 'a few modifications'. Does anybody know
where these modifications are documented? I guess there's nothing major,
reduce a few cap values? Remove Zobel Network etc.?? If anyone has
experience with this approach I would appreciate some hints.
Thanks.
Chris, G4AYT, Whitstable.
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