[Central-Electronics] Exciting Exciter VFO Option?

[Jim Candela]

Also realize that the 9 Mhz crystal will move a lot during the 1st hour of power up, and it will sometimes jump a few 100 hz on the way to being warmed up. My friend Hans Summers at qrp-labs.com has three kits that might be useful here.
1.) DDS VFO Kit, $33:  (BC458 replacement)

The Si5351A VFO/Signal Generator kit has a rotary-encoder tuned output, and a separate independent fixed (configurable) output. Both outputs have a range of approximately 3.5kHz to 290MHz. A GPS receiver can be connected to maintain precise frequency output.
2.) Band Pass Filter Kit, $4.90:   (convert square wave from the Si5351A to a sine wave)
This Band Pass Filter (BPF) kit is for receiver input filtering. It uses the popular double-tuned-circuit which is reliable and easy to build, without needing access to any special equipment. Kits are available for 10 HF bands 160, 80, 60, 40, 30, 20, 17, 15, 12, and 10m. The kit uses a high-quality double-sided PCB with silk-screen, solder-mask and through-hole plating. The capacitors supplied with the kit are high-quality RF ceramics of the C0G type (a.k.a. NP0 - near-zero temperature coefficient). Designed for the relay-switched LPF kit, or your own projects!
3.) Programmable crystal oscillator, $18: (Replace 9 Mhz crystal and drive pentode of 6U8A as a class A voltage amplifier)

This kit is a simple minimalist controller for the Si5351A Synth kit (included with the ProgRock kit). It is intended as a programmable crystal replacement. It has three independent outputs with frequency range 3.5kHz to approx 300MHz, and can be optionally GPS disciplined.
http://qrp-labs.com/

Lots of ways to stabilize the beasts in a 20a, I used an VHF highband xtal oven and a CB crystal (ch 3 xmit?) for 9 Mhz, and a Cumbria stabilized X-Lock to my band hopper VFO.

JimWd5JKO




 

    On Monday, December 12, 2016 1:21 PM, Jeffrey Welsh <radioartistry at gmail.com> wrote:
 

 I am working on the same idea, I purchased the ad9850 controlled by arduino, and built an amplifier with broadband toroid transformer.  It works, and now just need to test with the 20a.  I can send you a link of the amplifier schematic soon.
73
Jeff kd2azi

Sent from my iPhone

> On Dec 12, 2016, at 14:09, Stan McIntosh <mcinsand at gmail.com> wrote:
> 
> To all,
> 
> Last week, the Si5351 board from Adafruit caught my eye (
> https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout/overview).
> For right at $8, you get:  a board with three PLL oscillators, 8 kHz to 160
> MHz, and 3Vpp for much of the output range (*IF* I understand correctly).
> A couple are on the way to my place, and I have to wonder if this might be
> good for my bench, where it would be good to have one knob control outputs
> for the Drake (5.6+ MHz IF), 20A (once I get it going), and maybe a direct
> oscillator.  Am I missing something?  Also, since the DDS/PLL board has a
> low impedance output, could adjusting the voltage to match a 20A's VFO
> input just be a matter of using a toroid step-up transformer with the
> appropriate load resistor?
> 
> 73
> Stan
> KD4BTH
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