RE: LF: Re: Pre-amps on LF

[Andy <actalbot@southsurf.com>]

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, jan-martin.noding@telenor.com 
[SMTP:jan-martin.noding@telenor.com] 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: owner-rsgb_lf_group@blacksheep.org
> [mailto:owner-rsgb_lf_group@blacksheep.org]På; vegne av Claudio Pozzi
> Sendt: 10. januar 2005 11:46
> Til: rsgb_lf_group@blacksheep.org
> 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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