UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Quick-and-dirty 1MHz test oscillator.

G6Tanuki · 21st Apr 2018, 11:17 am

I kludged together a circuit and have the little thing oscillating away to itself quite happily. Seems to be about 40Hz low of 1MHz, which I find quite astounding considering there's no means of trimming it.

Harmonics detectable to 30MHz on my RACAL RA217D, but they're much weaker at 145MHz.

I'm thinking of building a MMIC-based broadband amplifier to see if that brings the VHF harmonics up at all.

I will also do some experimentation [heating with a hairdryer!] to test the thermal stability: I have in the past known soldering crystal-leadouts to cause an irreversible frequency-shift (which is a pain when you bought a job-lot of rocks then carefully selected the frequencies of the xtals for an 8-pole ladder filter only to find that after soldering some of them have wandered...)

21st Apr 2018, 11:17 am	#10
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 14,007	Re: Quick-and-dirty 1MHz test oscillator. I kludged together a circuit and have the little thing oscillating away to itself quite happily. Seems to be about 40Hz low of 1MHz, which I find quite astounding considering there's no means of trimming it. Harmonics detectable to 30MHz on my RACAL RA217D, but they're much weaker at 145MHz. I'm thinking of building a MMIC-based broadband amplifier to see if that brings the VHF harmonics up at all. I will also do some experimentation [heating with a hairdryer!] to test the thermal stability: I have in the past known soldering crystal-leadouts to cause an irreversible frequency-shift (which is a pain when you bought a job-lot of rocks then carefully selected the frequencies of the xtals for an 8-pole ladder filter only to find that after soldering some of them have wandered...)