[Collins] WARC XTALS for KWM-2A

[Dr. Gerald N. Johnson]

Yes, the easiest one probably is a DDS chip from Silicon Labs.
The SI570 is one of those chips. According to an on line article from 
K5BCQ its rated for 10 to 160 but his does about 3 to 250 Mhz in 1 Hz 
steps. Its been used with SDR like the Soft Rock and with coarser 
programming in the controller chip could easily do a Collins local 
oscillator. It might have more phase noise though which could be an 
impediment in a strong signal environment like Europe on 40 meters. The 
file I have on my other computer is titled "SI 570 kit from K5BCQ.pdf". 
He claims pretty good phase noise. Also I have saved a web page, 
"Si570_Kit_from_K5BCQ.htm" He uses a simple shaft encoder and with 
pushes on the encoder (a button) allows selecting the digit to be 
changed and then changing only that digit so moving in 100kHz or 1 MHz 
steps after setting in the 3.155 MHz offset would be fairly straight 
foward. No doubt a minor amount of software changes in the controller 
chip could allow the display to be direct reading in S-line lower side 
frequency range with maybe standard 50 or 100 kHz steps.

The kit was $40 and does include surface mount parts.

Its just one of many one chip synthesizers around these days.

Searching to find one I remembered I found:
http://www.pongrance.com/super-dds.html

There was a commercial crystal replacement crystal synthesizer, 
personified by:http://www.aade.com/About_PayPal.html#dfd2 at Almost All 
Digital Electronics made specifically for Collins.

That TTL logic circuit probably is still workable if Far Circuits has a 
PC board. 74HC CMOS will do the same exact functions as TTL a bit faster 
and with far less power consumption. But all the logic it took on 
several square inches of board these days can be had in a 5 x 7 mm 
package, or maybe even smaller.

I have a crystal pack so with my extra crystal socket, I'm covered 
though I like my FT-857D so well my S-line is rarely connected to power.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.


On 8/1/2012 3:40 PM, Dave Brown wrote:
>   I'm reminded by these posts that there was a Colins S-line etc crystal
> replacement synthesiser article quite some years ago in Ham Radio- has this
> idea ever been updated? IIRC that article used basic 7400 series TTL-I'd
> expect there's a 'better mousetrap' around these days....
>   73
>   Dave, ZL3FJ
>