Jeff,
You DO NOT want to use the 2" seizure screw probe you mentioned. It is commly called the "STS-Probe". It was something that was manufactured to make-up for the lack of a common diplexer testpoint in the GNA/TNA "B" and "D" versions. This probe is a basic screw-in "resistive" testpoint and will not give you a good match. You will see reflections, espically if you have a splice, close coupled passive or a 90-degree connector at the forward output both in the reverse and the forward.
Depending on what version you have there are various options for a good match and injection point. Your best bet is to inject into an external tap...and also confirm that any un-used forward ports are terminated in 75-ohms...even if the internal jumper is not active to that port, because it is still active in the return.
I was a field engineer with Philips Broadband Networks / Magnavox for years....so I can sympathize with your frustrations. I could tell you stories, espically when the customer or re-furb place changed the aluminim covers and you had to investigate what the module was and match up the puzzle. There are probebly around 25+ different versions of the GNA/TNA and all have their own different stories.
If I can help you in any way, please feel free to call me on my cellular or e-mail me. I have had good luck with the GNA/TNA and can help you if you would like.
Re: Test and sweeping probes for Magna(trash)vox
Member #: 7190
Registered: 1996-2001
Posted:
483
Name:
Greg Tobin
Name:
Greg Tobin
Company:
Interactive Broadband Technical Services
Occupation:
HFC Engineer/Consultant
Location:
www.interactive-broadband.com
Personal:
Experience:
~45 years
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