[minima] Re: Finally getting around to building my Minima...

  • From: José A. Amador Fundora <amador@xxxxxxxxxxxxxxxxxxxxxx>
  • To: minima@xxxxxxxxxxxxx
  • Date: Fri, 31 Mar 2017 21:30:12 -0500

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.


Jose, CO2JA

On 31/03/2017 10:57, Joe Rocci wrote:

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.


    - 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

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