Stephen Hall wrote:
> Hi All,
> I am building a monoband?amp and I would ask for advice as to which
> is the best configuration Full Bridge or Voltage doubler. Does one
> perform better than the other ,or is it just down to personal
> preference ?? Also should I use a torroid or conventional
> transformer which is prefered.
> Power?will be around 4Kv off load max current 1 amp using 240 volt
> UK mains single phase primary to power a GS35B for 50 Mhz.
To get the best out of a GS35b you need 3.5kV on-load. 3.2kV is marginal
and at 2.8kV it's really fading - the gain drops and it needs a lot of
drive. On the other hand, you don't want to go above 4kV off-load for
fear of internal arcing. To stay between those two limits implies that
your power supply needs good voltage regulation.
Full wave bridge has far better voltage regulation with most
transformers. Voltage-doubler requires a very low secondary resistance,
which most transformers don't have unless they're specifically designed
for that job.
There are some toroidal transformers available in the UK that will give
you about 3.5kV off-load in a voltage-doubler configuration but I'm not
aware of any big enough to meet your requirements. However, there is a
firm in Bradford that will wind conventional transformers to your
specification and they're very good. E-mail G0RUZ for details
(conrad.farlow@irgin.net).
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
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