OCXO from ebay  - Page 1
Forum section: electronics / general

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 03:03:35 pm
content: I'm mad and frustrated and trying to keep a cool head about this.After the replies in this threadhttps://www.eevblog.com/forum/projects/frequency-standard-ideas/I decided I wanted a very accurate 10Mhz oscillator so I found this one on ebay and messaged the sellerhttp://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=251355497721&ssPageName=ADME:X:RTQ:GB:1123I asked him if he checked each of the ocxo's before sending them out he said no there was no need and it would beexpensive to do that etc.So I decided to purchase one and waited a few weeks for it to arrive and it came this morning, I was so excitedlike it was christmass and then I hooked it up on my bench to find it approxomately 25Hz high which is massivly out of spec.my refernces are1) tcxo a that babysitter on here made for me then calibrated and adjusted it to be 9.999990 which you can see that in the above link at the end of the thread.2) ocxo which I bought secondhand from ebayhttp://www.ebay.co.uk/itm/300802349781?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649WWV the atomic clock on 10Mhz has a transmitter accuracy of 1 part per billion but the signal may degrade over airto 1 part in 100 million, thats +/- 0.1 Hznow my Yaesu 897d ham radio has a CW Tune indicator, when I tune in to WWV at exactly 10Mhz on the radio the Tune indicator is lit and stays lit if you go +/- 20 Hz , if you go +/- 30Hz the Tune indicator goes out, so that is how I know myradio is revieving accurately on frequency (and the fact it was £800 and is a few months old)So if I hook up the secondhand OCXO both of my counters report that it is exactly on frequency like +/- 1Hzalso the signal comming from the Oscilator is exactly the same as from WWV, so I am happy to belive this Oscillator isreasonably accurate.The tcxo send to me from babysitter on this forum he tuned to be 10Hz below 10Mhz and on both my countersit reads 9.999990 +/- 2Hz , so again thats good enough for me to belive my counters are accurate.but as I said the new ocxo from ebay is 25Hz high, the guy returned my email saying I can return it to him and once recievedi can get a refund or replacement but thats not so easy for me because I am dissabled and house bound, also sending itfrom the UK to to HK is going to be a lot more expensive I think than it cost him to send it to me, he did say he will pay the return post fees, but I need to get a qoute first, so two trips to a post office.The thing about this I am not sure about is at the end of his message he said the following"But I have to remind you that this is an ocxo, so the voltage control pin on this oscillator can't be left at floating state which may affects the frequency. And a normal oscillator with the control voltage would get you adjustment of 40Hz off 10MHz on up and down side. This may override the initial tolerance although this is not the main purpose. It is the temp stability that put the ocxo a top rating."My second hand ocxo's VC pin is disconnected and it's still accurateI think this is a mute point because even disconnected it should never be 25Hz out ?or am I doing something wrong ?

author: rolycat
author_rank: Super Contributor
timestamp: June 30, 2014, 03:21:18 pm
content: You do know you can adjust the frequency by applying a voltage to pin 1?Range is +/- 40Hz, which should let you set it exactly.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 03:33:27 pm
content: rolycat I messed up when i made the post, there is a lot more info there now, sorry about thatyeah you can adjust it but the reason i bout it is because it is meand to be accurate alreadythe only way i could adjust it is using my counter and that is calibrated to my other ocxoso I am not gaining anything by doing that, the reason i got the new ocxo is it should have beenmore precise and accurate than what i already have.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 03:39:15 pm
content: QuoteI can't see the ebay auction (ebay blocked at work) but a lot of modern OCXO'sonlyhave a voltage adjust pin for trimming.They drift a small amount - typically 0.5ppm/year which is 5Hz for a 10MHz osc - they have enough adjustment to give a 10 year lifespan.To be honest the ones which have a trimmer to adjust the frequencycouldbe adjusted by the seller but it's likely that the trip through the mail with its attendent jostling and mechanical shocks would move the frequency more than 25Hz

author: johansen
author_rank: Super Contributor
timestamp: June 30, 2014, 04:22:40 pm
content: no, you can't leave it floating. seems the data sheet for those devices specifies the calibration frequency with the voltage adjust pin grounded.note that the calibration frequency may not be 10Mhz because the voltage adjust limits are .5 volts to 5 volts. so, with it grounded, it may not be centered at 10mhz, and given the age, that's probably expected anyways

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 04:41:49 pm
content: OK, I can see the auction now - I've bought a couple of those OCXO's from that seller.QuoteNo, that's a specific variant which would have YA or YB in the part number in place of the V5 in the part number being sold.You have to drive pin1 with a voltage - I've always assumed that the "zero point" is approx VDD/2 and it would be sensible for the manufacturer to bias the pin so it sits there if unconnected but I don't know whether they do.Remember that OCXO's aren't about accuracy - that comes from an external source - but about stability.That said if yours is 25Hz out either pin 1 floats towards one end of the adjustment range (+/- 3ppm or 30Hz) or you have a marginal unit.I'd start by getting a couple of 1k resistors connected in series. Tie one end to VDD, one end to ground and connect the centre point to pin1, then see if the frequency looks any better.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 04:42:20 pm
content: here are some picturesbabysitters 9.999990 TCXOsecond hand OCXOnew ocxo from ebay

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 05:01:38 pm
content: QuoteHave you had a go at biasing pin 1 to 2.5V and checking?As you're in the UK if you want me to check it against my Rubidium standard and let you know what control voltage it needs for 10.000000MHz drop me a PM.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 05:10:21 pm
content: Hi grumpydocthanks for the advicehere is the voltage divider made from 1k resistorsI would love it checked but I am trying to work out if it is faulty at the moment.I thought just connect the supply and gnd and you would get 10.000000 out.

author: babysitter
author_rank: Frequent Contributor
timestamp: June 30, 2014, 05:16:05 pm
content: Aging might have prevented it from being at exactly 00000... at 2.5V - its a control voltage, you might need to go a bit up or down to hit exactly, you might use a 10K pot with its ends between 0V and 5V (or a VREF out pin of the OCXO?) and see if you can trim it above and below 10 MHz. If it is not symetrically, dont panic. In case you cant get it from one side of 10.000 MHz to the other - only then consider shipping back !

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 05:26:19 pm
content: OK, that's better and well within the 3ppm pull range but still notgreat.I don't know where the seller gets his "frequency tolerance 0.15ppm" from - that figure isn't in the datasheet, nor would I really expect it there.I'd sort-of expect a new module to be fairly close to 10MHz - common sense would suggest they'd set it that way after some initial ageing at the factory.As I said, I have bought a couple of these. At least one would/will not settle down very well at all. The seller says they are "new" but they could still be units that have failed QC, with sales like this one hopes that they are just part of a batch bought and no longer needed for whatever reason but it's always hard to tell.As I said, as long as you pay postage both ways I'll run it against my Rubidium unit (or the GPSDO if I'm feeling keen) and let you know what control voltage to to feed it. It will likely still drift though. Drop me a PM.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 05:27:20 pm
content: QuoteI'd have thought it would trim fine - it's only 1.8ppm out and the trim range is supposed to be 3ppm.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 06:25:11 pm
content: Update on this I replaced the 2 1K resistors with a 10K multiturn VRand i can adjust the OCXO from 9.999939 to 10.000060Vin = 4.9991.82v applied to voltage control (pin 1) bring the frequency to 10.000000 +/- the accuracy of my counter.So would we say that the OCXO is working correctly as intended ?

author: retrolefty
author_rank: Super Contributor
timestamp: June 30, 2014, 06:32:52 pm
content: Quote from: Flump on June 30, 2014, 06:25:11 pmI would. As others have implied you didn't purchase a 'primary standard' but rather a 'secondary standard' that when trimmed to agree with a primary standard will stay within specified accuracy.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 07:04:43 pm
content: QuoteWell, the control voltage range is OK - +/- 6ppm - nicely symmetrical which is actually fairly reassuring.We don't know anything about phase noise, temperature coefficients or age related drift but you're probably no too interested in those to be honestQuotePrimary standards aren't exactly household items. About the best you can get on ebay would be a rubidium unit or a GPSDO but these rather seem to have dried up at the moment.

author: Stray Electron
author_rank: Super Contributor
timestamp: June 30, 2014, 09:07:58 pm
content: OP said:also sending itfrom the UK to to HK is going to be a lot more expensive I think than it cost him to send it to me, he did say he will pay the return post fees, but I need to get a qoute first, so two trips to a post office.If you're still intent on sending it back OR just for future reference, there's no need to make two trips to the post office. If the seller wants it back then take take to the PO and send it. You don't need to get an estimate ahead of time. Seller can do that online if he wants one! Per E-bay's rules (in the US at least and I think world wide), if the seller sold you a "new" or "used" item that proves defective then theymustreimburse you for the return postage plus your costs including shipping and any fees that they charged. It's somewhat buried in Ebay's rules but you can look it up under returning an item. I just went through this with an automotive part that I bought. The seller described it as "used" which per E-bay's rules means that it has to be 100% functional. But when I got it it was a piece of crap and had obviously never been checked. I immediately opened a case against him and after that he resolved the case promptly.Having said that, if I'd gotten a reply like you did to your inquiry, I'd have never bought the item! It is NOT expensive to check an OCXO!

author: dannyf
author_rank: Super Contributor
timestamp: June 30, 2014, 09:48:40 pm
content: Maybe your expectation is unrealistic or unreasonable.there is a multitude of reasons why stuff on eBay is cheap, terrible service being one of them. If you want more service, maybe you should buy from someone offering such services, like a local shop, etc. And be expected to pay for such services.in this case, the seller told you upfront that he isn't offering such services and you decided to buy from him anyway.he delivered a product that performed in-spec per your measurement. And told you correctly that you can trim the frequency to your own spec.to me, he held his side of the bargain and earned the money. It is great that he offered a refund and offered to pay for the return postage.quite frankly I don't know why anyone would sell over eBay, unless he is making a killing. As much buyer protection as eBay offers, it sucks sellers dry.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 30, 2014, 10:06:23 pm
content: QuoteIt's getting to be more work to sell on ebay, that's true.It's also true that this is no bad thing, ebay is trying hard to clean up its act - I've felt for a long time that it wants to compete with the Amazon Marketplace and for that it needs reliable sellers so it has slowly been forcing sellers to improve (or jump ship).The latest wheeze is to manage the returns process - of course charging the seller for the return delivery.This does annoy me a bit. Not because I don't want to accept returns - far from it. I try to be as fair as possible with anyone who buys stuff from me and will happily take back stuff that doesn't work (rare, I hope) or doesn't work out. BUT I want to control that myself and use the most efficient service I can - not one which costs twice as much and co-incidentally happens to give ebay a cut.For that I have to thank not only ebay but all the sellers who refuse to take stuff back and generate a poor reputation for the rest of us.However if you want to sell 2nd hand test equipment it's essentially the only marketplace.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 10:59:20 pm
content: Hello dannybeing new to OCXO's in fact the only previous experience I have of themis from the 2nd hand unit i recently bought from ebay which did not need anyform of intervention to be +/- 2Hz, so I assumed this new OCXO would be thesame but more accurate, after all there is nothing in the advert that saysit had to be adjusted before use.Micro Crystal OCXOVT-BV5NEW OCXO Oscillator10 MHz / 0.15ppm (-20C ~ +70C) / DIP/ +5V Single SupplyFrequency Tolerance : +/- 0.15 ppm maxI agree with what you said mostly,he said after the sale that the frequency control pin could notbe left loose, if i had known that before the sale then I would not havebought it.So yeah you are right he delivered a working unit and held up his endof the deal but I feel it should have been made apparent that the OCXOneeded to be trimmed before use if you expected any kind of accuracy.Anyways all is well that ends well and I have given him good feedbackand i have learned a few more things about theseand thats never a bad thing.

author: dannyf
author_rank: Super Contributor
timestamp: June 30, 2014, 11:00:26 pm
content: QuoteI can understand their attempt at disciplining their sellers: to attract more buyers, which in turn makes ebay more valuable for sellers.What it also does is to attract moronic or even fraudulent buyers who take advantage of the buyer protection. This will drive up the prices for every good buyer. So there is a natural balance.In the end, I think a more efficient market place is beneficial to all. That means rating sellers AS WELL AS buyers, and to potentially offer different grades of services.Hopefully Alibaba's entrance into the market will help eBay find that compromise.

author: dannyf
author_rank: Super Contributor
timestamp: June 30, 2014, 11:06:44 pm
content: QuoteI wouldn't assume that.The datasheet says 3ppm frequency stability. Your measurement, if it is done after sufficient time for the oscillator to warm up, is 2.5ppm.QuoteI would rely on the datasheet instead.Actually, as an OCXO, yours is fairly inaccurate at 3ppm: most of OCXOs are <1ppm. Performance-wise, yours sounds more like a TCXO.

author: Flump
author_rank: Frequent Contributor
timestamp: June 30, 2014, 11:25:53 pm
content: Quote from: dannyf on June 30, 2014, 11:06:44 pm

author: dannyf
author_rank: Super Contributor
timestamp: June 30, 2014, 11:37:30 pm
content: You should measure the current into the ocxo. Or put a finger on it when it is powered. It should feel warm / hot.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 30, 2014, 11:52:10 pm
content: Hi,To the original poster.They are well insulated, I doubt you will feel the case warm up.Since an OCXO is an Oven controlled oscillator you should see the oven warm up.The way to test for test for this:Leave your frequency plugged in an on for several hours. This is to make that the oscillator in the counter is warmed up and not drifting.Take the OCXO that is cold, not been operated for several hours.Monitor the current consumption of the oscillator. The current consumption will drop when the OCXO reaches the operating temperature.The oscillator should drift in frequency until the operating temperature is reached. The temperature and frequency typically stabilize after 10 minutes.If the oven in the OCXO is broken you will see not see the frequency or current consumption change.I have fixed some HP 10811-60111 OCXO by replacing the thermal fuse. I have no experience with the unit you have.Regards,Jay_Diddy_B

author: babysitter
author_rank: Frequent Contributor
timestamp: July 01, 2014, 09:20:54 am
content: Let me summarize a bit about care and feeding of unknown OCXOs:Try to get the data sheet of your OCXO, it will tell you almost everything you need.The pin connected to the case is always GND. Try to find a hint at the internet which pin is actually supply voltage. Dont be surprised when discovering 2 supply voltages, one for the oven, one for the oscillator.Certainly you will find a Pin called control, Vtune, Utune,EFC, UEFC or such, this is a voltage that will pull the oscillator frequency around by means of a varicap inside. Sometimes you might find this pin internally biased to the midpoint, either VCC/2 or for example VREF/2 or something different which could be telling you "I am half the maximum voltage!"You can control this voltage with a potentiometer between ground and either oscillator supply or a additional UREF, VREF pin if available.You can reduce the adjustment range and subsequently have easier fine control by adding a series resistor between the wiper of your pot and the control input.The power consumption of the oscillator should be rather low but quite constant, I would consider 3 to 50 mA reasonable. The oven will start out drawing a lot of current in the beginning but decreasing after a few minutes. Above 1.5A initial, the oven current would look suspicious to me.Now you can watch the oscillator dance for a while - while the oven current starts up high but will settle to around 1/4th of inital current, the current consumption shall be quite stable after 5-60 Minutes. Oscillating current consumption points to a bad regulation, needs repair.The oscillator will start out far from its target frequency necessarily, most probably hundreds of Hz lower. It will home in on its target frequency with a similar behaviour as the oven but I saw that it will take longer usually. (Sample size 2.)If both don not stabilize, consider that you need more supply voltage.Setting the control voltage: Make sure that varying the control voltage varies the frequency in a consistent manner. lower voltage=higher frequency or vice versa, without kinks and bends. If you have a trusted 10 MHz Source, check if you can tune above and below 10 MHz.Half-range control voltage should be close to 10 MHz. It isnt necessarily symmetrical as aging might have moved the center f. Only if you can only tune above OR below 10 MHz, youre basically screwed - this damns you to memorizing or noting the difference you settled for and do some calculations if you use it.Coarse tuning can be done with any garden variety frequency counter. "Copying" the same frequency of a trusted source can be done by connecting both oscillators to a o-scope, triggering on the trusted one. you will see that your target oscillator signal runs relative to your trusted signal. When adjusting the tune voltage you will realise that it will either run faster (wrong direction!) or slows down (right direction) - and getting up to speed as soon as you are pulling behind the right frequency (getting wronger again). You want your target oscillators trace moving as slow as possible relative to the sources trace. Still standing over minutes or hours is perfect :-)@flump especially:You are not lost. The OCXO will provide a good stability. If you set it right now when both your fixed oscillaltor and also my -10 MHz source are new, they are probably quite accurate. Time will play less well with them. Setting your well-heated (over 24h)OCXOsoonaccording to them will be like a backup of their performance of nowadays!

author: grumpydoc
author_rank: Super Contributor
timestamp: July 01, 2014, 09:55:42 am
content: QuoteThis is about the only upside to managed returns that I can see - if buyers are repeatedly returning stuff then that should flag up to ebay. Whether they do much about it we'll see.

author: Flump
author_rank: Frequent Contributor
timestamp: July 04, 2014, 08:54:42 pm
content: Thanks very much babysitter fir the explanationI am sending my 2 OCXO to grumpydoc next weekto check against his rubidium reference,I will have 2 accurate ocxo + the FLUMPILLATOR O0so I will be all set then

author: grumpydoc
author_rank: Super Contributor
timestamp: July 27, 2014, 09:21:20 pm
content: Quote...which arrived a few days ago, I've just had chance to start to have a look at them.The Oscilloquartz unit which is definitely the better of the two is in good condition. With no connection to the adj pin it floated at about 3.3V and the output frequency was 9.99999886MHz or about 1.114Hz slow. Pulling adj to 4.745V gave an almost spot on 9.999999997MHz - 0.3ppb out and about as close as I can measure anyway.Given that the output is at 10MHz with the control voltage very close to the centre of its range (0-10V) means there's plenty of adjustment left and drift will have been well within spec. The current draw shows the oven control to be OK as well - starting about 0.5A, rising slightly to peak at 0.53A and settling at 0.22A with the unit warmed up (just slightly over spec as it's supposed to be < 2.5W warmed up but it's not too far off).I think Flump was most interested in the micro crystal unit - I'll have a look at that and some more checks on the Oscilloquartz unit next week.

author: dannyf
author_rank: Super Contributor
timestamp: July 27, 2014, 09:57:57 pm
content: Quote1w when warmed up is fairly typical.I have found that most of the times, a TCXO (2.5ppm for example) is fairly good, as they typically come in at around <1ppm unadjusted. The ones I am testing now consumes < 2ma and "warm" in seconds.

author: grumpydoc
author_rank: Super Contributor
timestamp: July 27, 2014, 10:07:10 pm
content: Quote from: dannyfThe 8663 is a 12V supply so this is 2.64W which is a bit over spec (< 2.5W) and it's warm in the workshop tonight - about 28oC so it shouldn't really need to be working that hard.However it's quite possible any insulating foam has deteriorated through use, explaining the higher draw. Certainly the outside of the unit is fairly warm.

author: dannyf
author_rank: Super Contributor
timestamp: July 27, 2014, 10:54:08 pm
content: They are usually warm to the touch so that doesn't surprise me.Maybe yours does run hotter. Or your room temperature is lower or has better ventilation, etc., causing the oven to consume more energy to maintain its desired temperature.

author: Flump
author_rank: Frequent Contributor
timestamp: July 27, 2014, 11:37:54 pm
content: I made a mistake buying the Micro Crystal unit, I thought it was going to be near enough spot on frequency like the Oscilloquartz one but better because it was new,Still it will be usefull to have another to use as a reference.I look for to see what the MC one is like and if it is stable.Thanks so far grumpydoc

author: grumpydoc
author_rank: Super Contributor
timestamp: July 28, 2014, 08:59:42 pm
content: QuoteI don't think that it was a mistake.However it is clear from the specs that the Oscilloquartz is the better unit.Turning to testing the Micro Crystal one....Hooking it up initial current draw is 190mA, falling to 60mA as it warms up so that looks good and all in spec.Leaving Vadjfloating it settles at around 2.97V and, at that, the output is 21.27Hz high - so Flump's original measurement of 25Hz high was pretty close to mine. Certainly close enough for most of the difference to be explained by supply voltage differences (following measurements at VDD= 5.002V), or ambient temp.Pulling the Vadjpin to 1.974V gets it pretty close - 10.000000114MHz just now, but it's a pig to adjust by hand and is drifting somewhat making it almost impossible to pin down better than about 1 in 107.Part of the reason it's harder to adjust is that the pull range of the MC unit is 10x the 8663 - ±3ppm (30Hz) rather than ±0.3ppm. This, in turn, is because the 10 year stability of the 8663 is 10x better than the MC one.The 8663 also has a better rejection of supply variations as well: 3x10-10over the 12V ±5% supply voltage range vs 1x10-7for the MC oscillator. Running on the breadboard I'm finding it hard to pin down the last mV of stability on VDDand Vadjand it definitely affects the MC unit more than the 8663.the 8663 is also massively better on variation vs ambient temp. The spec is 4x10-9over the operating temperature range of -20oC to +70oC. The corresponding figure for the MC unit is 150x10-9even for the "high stability" variant.At the end of the day this oscillator is probably in spec but playing with it mirrors the experience I had with another unit that I (coincidentally) bought off the same vendor - I just couldn't get it to settle down to much better than 10-7stability. Conversely another one I had (again from the same source) is much better behaved. I suspect the MC unit was designed assuming fairly tightly controlled supply voltage and probably the frequency control voltage coming from a DAC rather than a multi-turn trimpot.I think that if Flump wants a reference oscillator the 8663 is by far his best choice - if he drives the frequency control pin at 4.75V it will almost certainly be within 0.1Hz of 10MHz. To reliably get any more accurate I think will take a Rubidium standard or GPSDO - sadly both now seem very rare on ebay. In fact even cheap OCXO's are not as cheap or plentiful as 12-18 months ago.

author: Flump
author_rank: Frequent Contributor
timestamp: July 28, 2014, 09:25:15 pm
content: Grumpy thanks sooo much for checking them both out.On one hand I bought the MC XO which was a bit of a let downbut on the other the 8663 is really goodso I got what I needed in the end which was a decent 10Mhz reference.How long would the MC XO stay accurate for do you think ?10.000000114 is still pretty good.would the MC make a good reference for my dana counter ?as it just uses a standard 1Mhz crystal but it has an externalsocket for a reference, i could use a 10:1 divider on it.I'm loving the 8663 right now though lol

author: grumpydoc
author_rank: Super Contributor
timestamp: July 28, 2014, 09:51:51 pm
content: QuoteI've turned them off but over the space of this evening it drifted up about 0.1Hz to 10.000000208MHz. You can probably assume it's going to settle to within 1x10-7but I'm not sure it's going to be easy to get it better than this.If your Racal frequency meter has the 04C option it would be a better oscillator, if it has the 04T then maybe - if it's 04A or 04B then those are ovened oscillators and much closer to the 8663.I'd probably make a little PCB to go inside the Racal with a trimpot accessible from the rear of the counter. If you do this you need to divide by 2 as it's actually a 5MHz standard internally and watch for the fact that the OCXO supply is 12V, not 5. I actually bought mine to go in some Racal 19xx series counters as I acquired one with no oscillator and one with a broken one. As I said one is fine, the other I can't quite get to settle - rather like yours.Yes, the 8663 is one of the nicer OCXO's kicking around ebay - I used one to fix my GPSDO seehttps://www.eevblog.com/forum/repair/rapco-1804m-repair-10mhz-conversionbodge-(-teardown)/msg137237/#msg137237

author: Flump
author_rank: Frequent Contributor
timestamp: July 28, 2014, 10:32:07 pm
content: heres my osc boardand the pdf mine is the 9914I was going to use the xo as an external reference to leave the counter original and i think its 1mhz for thathttp://www.drop22.com/images/dana/Racal%20Counters1984-5%20%281%29.pdf

author: grumpydoc
author_rank: Super Contributor
timestamp: July 29, 2014, 07:12:33 am
content: QuoteYes, that's the 04C - un-compensated simple crystal osc. The idea was that would get the unit working but you'd use an external ref for any measurements.QuoteIt is. Doing it by replacing the PCB eliminates a box and some wiring but it will work just as well as an external standard.

author: wyphy
author_rank: Contributor
timestamp: August 06, 2014, 04:50:43 am
content: I'm a bit late to this party, but hey, I just joined the forum.I'm actually working on my own OCXO reference so the title caught my eye. (Shameless self promotion :https://www.eevblog.com/forum/projects/10mhz-ocxo-frequency-reference-project/)I also noticed that you mention the Yaesu 897D, so I presume you're an amateur radio op, which doubly made me think of something that W2AEW posted a couple years ago, and will get you to better than the +-20Hz you mentioned with the CW tuning indicator.Isn't quite so easy with a digital S-meter, but borrow something with a real analog S-meter and you'll be fine. My Kenwood TS-530 will do just fine for me.Cheers.