GPSDO 75-ohm splitter to multiple radio clock inputs?

[srletend]

Looking for some help: I'm using a Leo Bodnar Precision GPS Reference Clock to feed two radios with a 10MHZ clock signal. This device has two 50 ohm clock outputs. I would like to feed more radios with a clock signal. I'm thinking I could put a standard 75-ohm cable-TV type splitter on one of the GPSDO outputs and feed other radios off of that. The GPSDO output strength can be set, so I don't think there would be much signal loss. The output and the radios are all 50 ohm. Would the insertion of the 75 ohm splitter make a difference?

Suggestions appreciated. Thanks.

 

[merlin]

Plain cable splitters don't pass 10 MHZ well, if at all. Get splitters with 50 ohm ports and a bandpass good at 10 MHz.
Maybe something from the SAT TV arena. Or Agillent/HP.
Also, check your Bodner and its drive capabilities, more ports/loads need more drive. I believe all you need is 1 volt P-P
I use a Trimble and drives my signal generator, frequency counter, and spectrum analyzer. 2, T taps and through
Although intended for NMEA, it outputs 10 MHz also.

 

[dlwtrunked]

Looking for some help: I'm using a Leo Bodnar Precision GPS Reference Clock to feed two radios with a 10MHZ clock signal. This device has two 50 ohm clock outputs. I would like to feed more radios with a clock signal. I'm thinking I could put a standard 75-ohm cable-TV type splitter on one of the GPSDO outputs and feed other radios off of that. The GPSDO output strength can be set, so I don't think there would be much signal loss. The output and the radios are all 50 ohm. Would the insertion of the 75 ohm splitter make a difference?

Suggestions appreciated. Thanks.

Use one of these and appropriate cable (SMA from eBay jumper--do not mess with 75 ohm though the stiffness of that is more a problem).

Active RF Isolated Splitter for RF Signals Radio Antenna SDR GPSDO Source 150MHz | eBay

Active RF isolation distributor working frequency range: 100kHz to 150MHz, insertion loss is less than 0.8dB, the isolation between the output to the input is better than 80dB. Battery: 600 mAh battery inside.

www.ebay.com

or from https://www.aliexpress.com/item/3256805970956596.html
or Active RF Isolation Distributor RF Splitter For SDR GPSDO Source 1 | eBay
or 10MHz Distribution Amplifier for GPSDO OCXO With 4 Outputs | eBay (I use--4 outputs and higher price.)

Note it will convert the Bodnar GPSDO square wave to sinewave but that will be perfectly OK. Bodnar GPS are good stuff.

 

[dlwtrunked]

Also, which receivers are you GPS disciplining. I may have some comments regarding those.

 

[prcguy]

There have been problems reported with false triggering due to reflections in a 10MHz and similar reference distribution systems. Reflections can be caused from high VSWR. Just use 50 ohm cables and don’t cheap out on this.

 

[srletend]

Thanks for the replies—good stuff. For the question about the receivers I’m using: (1) Icom R8600, Airspy R2, SDRPlay RSPdx, a couple HackRFs.

 

[dlwtrunked]

Thanks for the replies—good stuff. For the question about the receivers I’m using: (1) Icom R8600, Airspy R2, SDRPlay RSPdx, a couple HackRFs.

My note is that a GPSDO added to most of those (Airspy, SDRPlay, and I think HacKRF 1, I do not recall) will not put them exactly on frequency but will give them the stability that you expect from a GPSDO. This is because those use a tuner that does not tune in very fine steps so you will often be some several MHz off (but will be even worse if you use some other calibration). One discovers this is one uses something like a GPSDO'ed Signal Hound spectrum analyzer and compare measurements to discover stuff that you had thought was a little off frequency with one of the GPSDO'ed SDRs are in fact exactly on frequency.

 

[srletend]

My note is that a GPSDO added to most of those (Airspy, SDRPlay, and I think HacKRF 1, I do not recall) will not put them exactly on frequency but will give them the stability that you expect from a GPSDO. This is because those use a tuner that does not tune in very fine steps so you will often be some several MHz off (but will be even worse if you use some other calibration). One discovers this is one uses something like a GPSDO'ed Signal Hound spectrum analyzer and compare measurements to discover stuff that you had thought was a little off frequency with one of the GPSDO'ed SDRs are in fact exactly on frequency.

Agree--that is what I have seen with the SDRs (frequency may not be true). It's the stability over time and temperature fluctuations that has been the biggest benefit.

I'm going to try one of e-bay items above (probably this one: 10MHz Distribution Amplifier for GPSDO OCXO With 4 Outputs | eBay). Will see how it goes. Thanks!