[hpsdr] Fwd: Horton Local Oscillator

[John B. Stephensen]

Yes, narrow-band VCOs will have much higher loaded Q and therefore less
close-in phase noise. Look at page 3 of the March, 2000 QEX for an example.
PIN diodes (or even reed relays) can be used for bandswitching, but since
transistors are cheap, you can also switch VCOs and get even higher Q.

73,

John
KD6OZH

----- Original Message ----- 
From: "Ahti Aintila" <oh2rz.sdr at gmail.com>
To: "Philip Covington" <p.covington at gmail.com>
Cc: "High Performance Software Defined Radio Discussion List"
<hpsdr at hpsdr.org>
Sent: Saturday, June 17, 2006 15:12 UTC
Subject: Re: [hpsdr] Fwd: Horton Local Oscillator


> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Phil & Phil and All,
>
> Please, don't stop this fruitful brainstorming!
> Here are my 2 eurocents.
>
> On 17/06/06, Philip Covington <p.covington at gmail.com> wrote:
> > ***** High Performance Software Defined Radio Discussion List *****
> > On 6/17/06, Don AE5K <don at ae5k.us> wrote:
> > > > <Posted on behalf of Phil VK6APH>
> < http://216.92.71.47/HPSDR/TEMP_STUFF/Horton%20Local%20Oscillator.doc >
>
> > > For discussion purposes it is assumed that the steps will be 10kHz and
> > > that interpolation within these steps will be done in PowerSDR.
> > >
> > > Maybe this is a naive question, but are we limiting "Horton" to
> > > receiving only HF ham bands?
>
> Phil_C answers:
> > Horton will not be ham band only.  I do not intend Horton to have its
> > own LO on board.  The coverage will be determined by what/which LO is
> > driving Horton's QSD.
> > That means Horton can be driven by a DDS, PLL, Signal Generator,
> > Crystal or whatever. The "whatever" is external to Horton.
>
> "Further thoughts" of Phil_H indicate that it is better to use narrow
> bands for voltage control of the oscillator and switch capacitors for
> those many bands needed to cover outside the ham band frequencies,
> too. It is obvious that a combination of switched capacitors will be
> needed. Without any calculations I assume that 16 bits can combine
> capacitance values needed at least for the whole HF spectrum.
>
> It may be true that this innovation, by eliminating the need of DDS
> solutions, will change a lot of the future radio architecture. Isn't
> that what we all want with this exercise?
>
> 73, Ahti OH2RZ
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