CTI OSC5A2B02 - Page 1
Forum section: electronics / testgear

author: BillyO
author_rank: Super Contributor
timestamp: March 06, 2023, 11:02:24 pm
content: Just received 6 of these. Cost me less than $17 for all 6.I wasn't expecting much, but the specs on them are pretty respectable and when I hooked one up to my scope I got as pictured.That's through a 1 meter piece of RG316. Much better than I expected and quite decent for less than $3 each.Will make a decent enough timebase for me, especially after I tweak against a GPSDO

author: 807
author_rank: Frequent Contributor
timestamp: March 07, 2023, 12:33:39 pm
content: I was impressed with the stability of these OCXO's after buying a complete module for around £19. The tuning voltage range wasn't set right on the module, but that was overcome with a couple of resistor changes.I've now bought 4 of the OCXO's from China to play around with. Going to replace the timebase in my Racal Dana 1991 & 1998 frequency counters.

author: MIS42N
author_rank: Frequent Contributor
timestamp: March 13, 2023, 01:04:29 am
content: I have been playing with these for a couple of years. Out of maybe a dozen, one failed. The input impedance went low so the control voltage couldn't be set.With the default control voltage of 2V the worst case error so far is about 4Hz.From a cold start, the output is useless for about 3 minutes, and will settle within 15 minutes. With a calibrated control voltage it will be within 1Hz of 10MHz. There is significant drift for a day, and a little bit more for a week. After that they are reasonably stable.I use them in experimental GPSDOs. I have not been able to get stability consistently below about 0.5mHz (i.e about 5 parts in 10^-11). I don't know if this is GPS, OCXO, environmental effects or bad design. Maybe a bit of all of them.As part of a hobby GPSDO, they are excellent value.

author: ME
author_rank: Frequent Contributor
timestamp: February 16, 2025, 09:46:01 am
content: I have just got one of these, It runs at 99999603Hz with the pot wound to its max,what resistors did you change?.

author: 807
author_rank: Frequent Contributor
timestamp: February 16, 2025, 11:25:28 am
content: Quote from: ME on February 16, 2025, 09:46:01 amIn my case the oscillator was 3Hz high, so I needed to halve the values of R1 & R3. At -40Hz, yours is quite a lot further out than mine. Have a look at the circuit diagram I reverse engineered. Adjust your pot & measure the voltage on the Vref pin while observing the frequency. By extrapolation, it may give you an idea as to what Vref voltage is required for 10MHz. Then calculate the values needed in the resistor divider chain.You could also try using an external PSU to determine the Vref required.edit...are you using a GPSDO or rubidium standard to measure the frequency of the oscillator?https://www.eevblog.com/forum/projects/cheap-chinese-ocxo-frequency-reference-modules/msg4728044/#msg4728044

author: ME
author_rank: Frequent Contributor
timestamp: February 26, 2025, 08:58:20 am
content: Well an update. I thought i would take another look at this, Hooked it up to my counter to be met with a readout of all zeros!, I thought blast my counter had died so connected it to my dso, All i got was a flat line except the nc pin that had a sinewave of about 5mv peak to peak, I have just ordered 5 of the oscillator bare cans for less than a fiver and a dpsdo for £47 so we will see how they are.

author: jdev99
author_rank: Regular Contributor
timestamp: June 26, 2025, 02:23:07 pm
content: Hi ME,Where did you buy these for less then a fiver? I need 1 for a small counter project.Thank you for any information.Joe