Even 1N4148 doesn't add more attenuation than a fraction of dB. so I really
doubt the statement, the only real problem is possible intermodulation
73
Jan-Martin, LA8AK
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Fra: [email protected]
[mailto:[email protected]]På; vegne av Claudio Pozzi
Sendt: 10. januar 2005 11:46
Til: [email protected]
Emne: Re: LF: Re: Pre-amps on LF
On Saturday 08 January 2005 17:48, Joe Craig wrote:
Dear LF Group,
Getting back to the FT-817, is it possible to
modify the front end or first mixer so that
a preamp would be unnecessary?
Many RTX uses inexpensive diodes in the front-end design, for bandpass
filter and preamp and attenuator switching.
Also if they used more expensive PIN diodes those devices are not the
best switching devices for LF. A 100 kHz PIN diode switching devices
require a minority carrier lifetime of few ten's of microseconds. If
the life time is shorter the diodes acts as a rectifier, not as a
switch. I don't know many PIN diodes useful in LF band.
So I think that the problem is not in the mixer but in band switching
devices.
73 de Claudio, ik2pii
--
Claudio Pozzi - Happy Linux User - http://www.qsl.net/ik2pii
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