This is part of my Frequency Standard System.
Oscillator VEB Narva 10Mhz
The 10MHz TCXO itself is from east Germany made by NARVA. According to the data sheet it has a tolerance of ±2e-6, an aging of ±1e-6 and a thermal precision of ±3e-6. Given the timestamp of 1983 on it, it will have a deviation of approximately 3.7e-5 at this point.
The TCXO power circuit consists of a 555 timer with an ON-delay of a couple of seconds to ensure the supply has stabilized. It is then heavily filtered through inductors and low-ESR capacitors.
The pulse amplifier uses a BC547 and a BF254 transistor both in an AC couples configuration. The first stage using the BC547 amplifies the 50μVp-p signal from the oscillator to around 1Vp-p. The second stage with the BF254 offsets the signal to DC, such that it is within 0-5V and amplifies it to 0.7-4.7V, this is enough to trigger 7400 series TTL chips.
Currently I’m using a 74HC08 as an output buffer, this is not the fastest TTL chip available but it was the best I had around. The rise time of the output pulses is longer than I would like but it works for now.
The finished module
According to my Philips PM6666 frequency counter, it’s virtually spot on to the precision of the counter itself.