Joe,
the open loop stability isn't that bad if you made it well enough. the fast
huff and puff can correct quite well into the late 30Ms.
- f
On Sat, Apr 1, 2017 at 8:00 AM, José A. Amador Fundora <
amador@xxxxxxxxxxxxxxxxxxxxxx> wrote:
Perhaps, as commercial radios do, split the range between several VCO's.
It won't be as simple, but perhaps more manageable in practice.
There is a russian book about a homebrew transceiver that uses a single
VFO in the VHF range, and dividers to get the heterodyne signal on the
range it is needed. No VFO switching, which makes it rock solid, but rather
divider ratio change.
My Motorola MICOM-XL uses a VCO up to 360 MHz for 30 MHz which is quite
quiet phase-noise wise.
73,
Jose, CO2JA
On 31/03/2017 10:57, Joe Rocci wrote:
Also...
The open-loop stability of the oscillator, especially the 7-20 range, will
probably be too poor for the huff-puff to keep up and microphonics will
undoubtedly be an issue. Overall, a very daunting project in my estimation.
*From:* Ashhar Farhan
*Sent:* Friday, March 31, 2017 11:24 AM
*To:* minima@xxxxxxxxxxxxx
*Subject:* [minima] Re: Finally getting around to building my Minima...
A simpler scheme than the Si570 is to use a lower frequency IF like 11
MHz.
Make a solid JFET VFO in a shielded box that has two sections, one that
goes from 3 MHz to 7 MHz, the other that goes from 7 MHz to 20 MHz. Then,
just add a very simple Huff and Puff.
This scheme may look basic, it is not. The phase noise of such a system
will beat the best of the radios on the market.
It is not exactly easy either. First, you need a very nice tuning
capacitor with slow motion drive. Next, you will need good mechanical
skills to build the VFO.
- f
On Fri, Mar 31, 2017 at 7:59 PM, Mark Pilant <mark@xxxxxxxxx> wrote:
My plan all along has been to try different mixers. First the KISS mixer,
then a Mini-Circuits ADE-1, and finally the FST3253. I'm sure it will be
an interesting exercise.
73
- Mark N1VQW
--
MSc. Ing. Jose Angel Amador Fundora
Profesor Auxiliar
Departamento de Telecomunicaciones y Telemática
Facultad de Ingenieria Eléctrica, CUJAE
Calle 114 #11901 e/ Rotonda y Ciclovía
Marianao 11500, La Habana, Cuba
Tel: +53 7266-3445
Email: amador at electrica.cujae.edu.cu
