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RE: LF: Re: Pre-amps on LF

To: "'[email protected]'" <[email protected]>
Subject: RE: LF: Re: Pre-amps on LF
From: Andy <[email protected]>
Date: Mon, 10 Jan 2005 14:31:38 -0000
Importance: high
Organization: UKNWN(UK)
Reply-to: [email protected]
Sender: [email protected]
Many receivers probably have a high pass filter to reduce strong broadcast signals below 1.6MHz
Andy  G4JNT

On Monday, January 10, 2005 12:23 PM, [email protected] [SMTP:[email protected]] wrote:
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

-----Opprinnelig melding-----
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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