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Date: Tue, 21 Jan 2003 15:42:03 +0100
Message-ID: <2D280BB697C7EE4C979C5C89925418EFB05A45@TNS-FBU-2E-003.corp.telenor.no>
Thread-Topic: Jan-Martin's Preamp circuit
Thread-Index: AcLBWGTa58y2IkWYTLGMVPSMFV1hdgAAoJEQ
From: jan-martin.noding@telenor.com
To: rsgb_lf_group@blacksheep.org
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Subject: LF: SV: Jan-Martin's Preamp circuit
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TNX
This was constructed in times where we listened to BBC2 and no lower frequencies, so the capacitors are probably small.
Perhaps a resistor in series with the 10nF capacitor to adjust the positive feedback... hi
73
Jan-Martin
---
J M Nøding, Datakvalitet, TTS, Kristiansand
Telefon 0047-9077-7126


-----Opprinnelig melding-----
Fra: Hugh M0WYE [mailto:m0wye@thersgb.net]
Sendt: 21. januar 2003 15:11
Til: rsgb_lf_group@blacksheep.org
Emne: LF: Jan-Martin's Preamp circuit


Hi Jan-Martin and LF group,
I was going to ask if your preamp could be posted on the Reflector ...
Being the "some-other" Here it is ...
73
Hugh M0WYE

----- Original Message -----
From: <jan-martin.noding@telenor.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, January 21, 2003 1:10 PM
Subject: LF: Re: Re: Notch for DCF39/Spectrograms/Luxembourg effect


> Hi,
> I don't see the point in using NPN devices (PNP are better for this
purpose),
> you would probably not have more than 0.5x voltage gain
> A source follower has incredible low gain - even when driving high
impedance,
> that's the reason I discard such constructions, but using a PNP instead of
NPN
> you may achieve over unity gain. A BJT emitter follower has in the region
of
> 0.8-0.95x voltage gain.
> You set the feedback to adjust the gain, and add some postive feedback to
> the input and achieve very high input impedance.
>
> Unfortunately I forgot to forward the circuit from home, but sent it to
Alan
> and some other. Too high gain is of course a problem and may cause some
IMD,
> will try to remember to pass the circuit later (I am in Stavanger at the
moment).
>
> Passed the spectrogram as a separate mail
>
> 73 Jan-Martin
> LA8AK
>