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Racal dana 9442 frequency standard

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dr pepper

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I just got one of these on the 'bay.
A datasheet is proving difficult to find, any help with the pinouts would be great.
Its a 7 pin, and this particular version I think is 5v.
Not sure whether I'll keep the guts or put my own board in there, we'll see if its any good, I will be putting a ds18b20 in the oven so it can be monitored, or maybe a lm35 if I dont go with a microcontroller.
 
If the part number reflects 9442/5 the 5 I believe is 5 MHz. I am winging it on this but if you open it up I think it uses an oven to maintain a quartz crystal stability. You may be able to decipher the heater leads. You may also find some pins are No Connection. Years ago I did work with similar crystal ovens of HP manufacture. The US spec versions used mains voltage (always on) to maintain the oven. The HP units I recall had everything enclosed including the power supply for the oscillator circuit and were 10 MHz output square wave.

Ron
 
What I have is just the tin box with the oven/osc inside, however I'll sift through that and see if theres a pinout for the osc.

I originally got this just for the oven, as I want to improve my existing standard locked to radio 4, it doesnt have a oven currently, that said I might well use the whole thing if it looks good, I'll re connect the dividers to give me the correct freq for the pll.

Of course the first ting I'll do is pull it to bits, I'm expecting some electronics controlling the oven temp, and some more for the osc, I think its a sine o/p so there probably isnt much by way of an osc circuit.
 
It is probably made by Vectron who are still the leaders. I used one back in '76

https://www.vectron.com/products/holdover/index.htm You can report the oven p/n or power it up and measure. Yes it will be sine out. With power for heater, , analog and other bits. Vectron also has many docs on line for synthesis.

Std OCXO are < 10 in 10^-10 over env. range
better ones are 1 e-11

Sine is always best for low phase noise and EMI.
 
Hmm cant find any data still, I think pulling the lid off and looking in is the favorite.
Also I think the module is incomplete as references to it on the web show it with a base (socket and bracket) which includes another board part of the base, this is not included, I suspect this board will be the temp controller, as the seller shows the unit croc clipped up and showing 5mc's on a freq counter, so the osc circuit must be built in to the module, so the seperate board on the socket bracket is either temp control or perhaps a buffer amp, hopefully the latter.
I did find a pdf that shows rudimentary info, the /5 means 5v supply.
I might have to use a pic and a ds18b20 to control the heater, thought that entails a load of testing that I wanted to avoid.
 
Cant you just scope the or DMM the signals and send pix of OCXO

Usually OCXO is self contained heater, regulator and osc. So just +5V Sig gnd and maybe Vcontrol for f tuning.
 
Maybe your right, I'll know more when it comes in the post.

I got an ex mil one a while back, its a very nice piece of kit, it now holds a ad9850 dds module, pic micro, and reg, its an excellent little oven.
 
Ovens are easy to make. THe trick is the expensive SC cut crystal and knowing the exact temperature that the crystal temp curve is flat at the bottom of a parabola and regulating at that temp with enough insulation to give a thermal time constant of >10 Minutes and enough stability with thermal stress.

We used to 20 cent AT cut crystals that were 50 ppm and designed them to make a 1 ppm TCXO.

For calibration they were quickly testing in 30 seconds by putting SMT heater R's on a flexPCB inside a foam holder to enclose the metal can XTAL and heat up the crystal. It was thermally regulated with a switch to select 40 or 70'C and took 5 seconds to reach Feedback was inside using a thermistor and outside a programmable LDO.

After measuring the delta f at two temperatures 40 & 70'C using a 3rd order formula, came up with , derived from the AT curves. So I could predict the error from -40 to +40'C and compensate with a varicap and uC lookup table to DAC for under $1. It also was used as a wireless 2 way SCADA meter reading device to regulate the transmitter frequency in 928MHz band. That was 30yrs ago.

Now you can buy an AT cut 1 ppm TCXO or $1 but the SC cut OCXO has 3 orders higher Q, stability and better phase noise and cost $100.
 
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I got the standard today.
Pulled the lid off first thing, there are 3 wires from the 7 pin to the internal pcb, black, red and green, so thats self explanatory.
I was hoping there would be a control voltage i/p to tune the o/p freq, but there isnt, just a adjustable inductor through the lid.
The whole thing is glued up too, there may be some room on the pcb for a varactor and cap.
 
The crystal must be well aged by now, so unless it is contaminated, or you contaminate it by exposing it, the aging rate should be 10e-10 to +/-1 per year.
 
its about 30 years I'd say, I think the aging is less than that 1x10-11/year, so it'll be around 3x10-10.
 
It will easy to find the solution if you can post the picture here also. If it is 7 pin then it looks like the frequency stabilizer. There are other methods also to make an oven. Also if you want to use LM35 with the microcontroller, no problem. It will work.

Leiterplattenbestückung
 
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Don't expose the crystal to contaminants if not sealed inside.
Aging is usually metal diffusion even if pins are gold plated.

They should have used ruggedized tuneable inductors to survive lots of shock and vibe and have a ruggedized crystal mount.
It's probably series resonant sine out.
 
Welcome to the forum.
I did sort it with an lm35, but no micro his time, just a lf358 and some comps.
 
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