Workbench/frequency counter hookup

[2FB327]

Picked up a Tebna 72-4095 and why the book explains all the controls, I need some help.
1. What type of probe will I need or can make to pick up the signal?

2. It's has a channel A and channel B, is it possible to hook it in line with a scope?

I'm looking at doing bench repair, so is it possible to probe the radio and have the signal go from the probe thru the counter into the scope and then to the dummy load?

Thanx

 

[Robb]

A 10:1 attenuated probe has an adjustable capacitor near the tip so that it will not affecting the circuit that it is on ('capacitive loading'). But that doesn't mean that it cannot pull a freq down somewhat.

https://www.youtube.com/watch?v=SX4HGNWBe5M

 

[Beetle]

Picked up a Tebna 72-4095 and why the book explains all the controls, I need some help.
1. What type of probe will I need or can make to pick up the signal?

2. It's has a channel A and channel B, is it possible to hook it in line with a scope?

I'm looking at doing bench repair, so is it possible to probe the radio and have the signal go from the probe thru the counter into the scope and then to the dummy load?

Thanx

Not very practical. Connect them in parallel across the circuitry you're measuring. Be careful not to exceed max peak voltages, especially across the counter. 10:1 probes should be presumed to work until proven otherwise.

 

[2FB327]

Thanks

Thanks you both for your quick response.
I'll keep the counter seperate, it's starting to make sense.
Still waiting on the scope to arrive.

Could you recomend a supplier for probes, connectors, cable, etc?

 

[TonyV225]

RF Samplers are nice to have aswell. Though not cheap there good to have and are handy.

 

[Robb]

Once you've built an RF Sampler, you can run that to a 'T' connector. You can build one of those too. From the RF Sampler to the 'T' connector and from there to the scope and the other to the counter. OF course, this setup is used to sample radio OUTPUT; not sampling signals from inside the radio.

http://www.worldwidedx.com/home-brew/32110-rf-sampler.html


I use a probe and a freq counter to test the Reference Oscillator crystal ('RO'), where a signal can be monitored from one leg on the PLL chip. Just about every radio has an RO and they must be within freq tolerance, or you must replace it or adjust it. Many radios don't have an adjustment for this crystal; so you either replace it or add a compression capacitor to one leg of the crystal so it can be adjusted and pull it back into specs.


SO long as the probe you get is 10:1 attenuated and has a tunable cap in it (most of them do), it should work OK. If it has a swichable attenuation built in; so much the better but not necessary. Probably get one from eBay or several places on the internet. Not too expensive and should be about ~$25.

https://www.valuetronics.com/detail...gclid=COamsLGiuLkCFaU5QgodnXAASw#.UiqTSca1FmM

I use grabber clips on a coax cable with a BNC connector and the freq counter to test signals inside of the radio, as they make it easy for hands-free operation when going through the alignment procedure.

http://www.amazon.com/Elenco-Electronics-TL-3-Minigrabber-Test/dp/B0002JJU14

 

[camaro1]

a guy was selling pairs of these( Elenco Electronics TL-3 BNC to Minigrabber Test Lead Set - Amazon.com ) for $10 on ebay so I picked up a pair and a TEKTRONIX CFC250 frequency counter for $45 do I need to use a capacitor between the radio and test probe so the counter wont load the radio?

 

[2FB327]

Thanks everyone.
Rob, just what I needed, I'll get to making the RF sampler and ordering the probes.
Where do you get your parts, like the BNC connectors for in the boxes?