[ASK] Distributing 10 MHz reference signal for T&M equipments.

[BravoV]

Can I use this kind of "cheap" video Serial Digital Interface (SDI) splitter/distributor box to distribute the reference 10MHz signal from the GPSDO board ?

Example at Aliexpress -> Cheap SDI splitter
No affiliation with seller, just searched for "sdi splitter", choose the one with 4 outputs and sorted by price. 


Click to enlarge photos.


Btw, what is that "Lock" LED indicator for ?

[ogden]

Can I use this kind of "cheap" video Serial Digital Interface (SDI) splitter/distributor box to distribute the reference 10MHz signal from the GPSDO board ?

Example at Aliexpress -> Cheap SDI splitter
No affiliation with seller, just searched for "sdi splitter", choose the one with 4 outputs and sorted by price. 


Click to enlarge photos.


Btw, what is that "Lock" LED indicator for ?

"Lock" led could indicate that this is SDI digital regenerator, thus not compatible with 10MHz signal distribution.

You shall search not "SDI splitter" but "composite video splitter BNC".

Like this random google hit:

http://www.thesmarte-mart.com/ProductDetails.asp?ProductCode=SB-3701BNC

[douardda]

Can I use this kind of "cheap" video Serial Digital Interface (SDI) splitter/distributor box to distribute the reference 10MHz signal from the GPSDO board ?

Example at Aliexpress -> Cheap SDI splitter
No affiliation with seller, just searched for "sdi splitter", choose the one with 4 outputs and sorted by price.  [emoji14]


Click to enlarge photos.


Btw, what is that "Lock" LED indicator for ?

"Lock" led could indicate that this is SDI digital regenerator, thus not compatible with 10MHz signal distribution.

You shall search not "SDI splitter" but "composite video splitter BNC".

Like this random google hit:

http://www.thesmarte-mart.com/ProductDetails.asp?ProductCode=SB-3701BNC

I am in the process of building a 10MHz reference source for my lab. It's based on a pretty stable OCXO and an Extron video amplifier. I believe there are other people on the forum we did use such a device to achieve the same goal.
The main point to be aware of is the fact these are generally 75ohm. Whether you want to fix that or not is up to you. Not sure what are the real drawbacks of keeping as is, for a 10MHz signal it should not be such a big deal.

In my ref source, I'll also include a rubidium source I purchased years ago (an Efratom LPRO 101) for calibration purpose or when I need really a precise 10MHz signal.

David


Envoyé de mon GT-N7105 en utilisant Tapatalk

[ogden]

The main point to be aware of is the fact these are generally 75ohm. Whether you want to fix that or not is up to you. Not sure what are the real drawbacks of keeping as is, for a 10MHz signal it should not be such a big deal.

Attenuation of 50/75 Ohm "mismatch" is very small, around 0.2dB or so. Not worth to even consider "fixing" anything here.

[douardda]

The main point to be aware of is the fact these are generally 75ohm. Whether you want to fix that or not is up to you. Not sure what are the real drawbacks of keeping as is, for a 10MHz signal it should not be such a big deal.

Attenuation of 50/75 Ohm "mismatch" is very small, around 0.2dB or so. Not worth to even consider "fixing" anything here.

Yes that what I had in mind but since I did not do the math I wasn't sure the order of magnitude of this impedance mismatch.

Envoyé de mon GT-N7105 en utilisant Tapatalk

[BravoV]

"Lock" led could indicate that this is SDI digital regenerator, thus not compatible with 10MHz signal distribution.

You shall search not "SDI splitter" but "composite video splitter BNC".

Like this random google hit:

http://www.thesmarte-mart.com/ProductDetails.asp?ProductCode=SB-3701BNC

Thanks  , good to know before I made the mistake.

Something like this should be fine right ? -> 1 Input 8 Output BNC Splitter

[ogden]

"Lock" led could indicate that this is SDI digital regenerator, thus not compatible with 10MHz signal distribution.

You shall search not "SDI splitter" but "composite video splitter BNC".

Like this random google hit:

Thanks  , good to know before I made the mistake.

Something like this should be fine right ? -> 1 Input 8 Output BNC Splitter

Not good. Bandwidth is just 5.5 MHz. There shall be better choices around. Keep looking

[BravoV]

Not good. Bandwidth is just 5.5 MHz. There shall be better choices around. Keep looking

Yeah  , what a bummer.

Will keep looking, as I'm just hobbyist, I will try to keep at minimal cost as possible.

Btw , what the heck is that upper limit 5.5 MHz signal for ? Suitable for analog CCTV signal ?

[GerryBags]

I think you want a distribution amplifier rather than jut a splitter. This one is new (https://www.cctvcamerapros.com/CCTV-Video-Distribution-Amplifier-p/amp-1632.htm), but I've seen lots of 2nd hand units come up on Ebay for around $100 US fairly regularly.

[ogden]

I think you want a distribution amplifier rather than jut a splitter. This one is new (https://www.cctvcamerapros.com/CCTV-Video-Distribution-Amplifier-p/amp-1632.htm), but I've seen lots of 2nd hand units come up on Ebay for around $100 US fairly regularly.

Let's check "splitter" I mentioned. First thing we do - carefully read URL: https://www.cctvcamerapros.com/CCTV-Video-Distribution-Amplifier-p/amp-1632.htm. There's specs which say that it's Amplifier indeed:

The SB-3701BNC is a 1 in to 4 out Composite BNC Video Distribution Amplifier. Used to distribute video signals to multiple destinations, this product allows up to 4 outputs that are identical to the source signal. Works with any video source with a Composite BNC connector. Video signals can be distributed from up to 300ft (100m). For proper amplification, make sure that your video source is closely located to the amplifier and connected with a short cable.

[GerryBags]

First thing we do - carefully read URL:

Yes, I must have missed that. My apologies.

[DaJMasta]

There's a decent sized recent thread on making your own/buying/converting distribution amplifiers for 10MHz frequency references in the T&M forum, may be worth a search.

[ogden]

First thing we do - carefully read URL:

Yes, I must have missed that. My apologies.

My apologies as well. Some clipboard hiccup happened, I managed copy/paste yours, not mine URL   Anyway product I refer to, indeed is distribution amplifier.

[ahbushnell]

The main point to be aware of is the fact these are generally 75ohm. Whether you want to fix that or not is up to you. Not sure what are the real drawbacks of keeping as is, for a 10MHz signal it should not be such a big deal.

Attenuation of 50/75 Ohm "mismatch" is very small, around 0.2dB or so. Not worth to even consider "fixing" anything here.

If you put 25 ohms in front of 50 to get 75 ohms to match then the attenuation would be
50/75
or in dB
20*log(50/(75))=-3.5 dB

Did I miss something?

[ogden]

The main point to be aware of is the fact these are generally 75ohm. Whether you want to fix that or not is up to you. Not sure what are the real drawbacks of keeping as is, for a 10MHz signal it should not be such a big deal.

Attenuation of 50/75 Ohm "mismatch" is very small, around 0.2dB or so. Not worth to even consider "fixing" anything here.

If you put 25 ohms in front of 50 to get 75 ohms to match then the attenuation would be
50/75
or in dB
20*log(50/(75))=-3.5 dB

Did I miss something?

You do not put anything anywhere. Just connect 50 ohm cable and connector to 75 ohm socket of 75 ohm device, getting 0.2dB loss due to impedance mismatch.

https://www.eevblog.com/forum/beginners/using-75-ohm-attenuators-for-50-ohm-applications/

http://chemandy.com/calculators/return-loss-and-mismatch-calculator.htm

[BravoV]

There's a decent sized recent thread on making your own/buying/converting distribution amplifiers for 10MHz frequency references in the T&M forum, may be worth a search.

Thanks, just searched and its interesting.

Also I found your design, can I get the schematic say in PDF rather have to sign in ?