[HomeBrew] RE: Options For FM RX & TX Crystal Replacement?

[Robert McConnell]

At 2/18/02 10:41 AM +0900, LIM,CHIN-LEONG (A-Malaysia,ex2) wrote:

>The plain vanilla synthesizer is stable enough for most application below 70
>cm. Above 70 cm, you may need to temperature compensate the synthesizer's
>reference crystal, eg. OCXO or TCXO. Additionally, the stability requirement
>is different depending on the modulation - SSB being more demanding than FM.
>
>DCkit (in US) and Minikits (in Australia) have synthesizer kits that may
>work with your application. Both companies advertise their products on the
>web. Their web addresses are listed below:-

The military receiver R-1051 is a synthesized unit. It covers 2-30MHz, and 
was specced to have less than 1 Hz drift per day. However, the oscillator 
circuits are in an oven, kept at a stable temperature. The adjustment 
required the tech to make a change, then wait ten minutes before testing it 
to allow the oven to return to the correct temperature after the 
screwdriver was removed. Unfortunately, that module had to be replaced 
after about 10,000 rounds from our 5" guns. During our last six month trip 
to the Gulf of Tonkin ('72-'73), we had to replace all 9 of them at least once.

Wasn't there an article in Ham Magazine in '73 or '74 describing how to 
build a crystal oscillator with temperature correction using some caps with 
negative temperature coefficients? If your base frequency standard is 
accurate enough, the synthesizer would be quite stable.

Bob McConnell
N2SPP