w4wt
New Member
Posts: 1
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Post by w4wt on Aug 10, 2019 14:29:58 GMT -5
I don't know if I am doing something wrong or not but I can not get accurate results from the TDR function on 915a or 916; just 910b. What I see is an incorrect length being reported where it is indicating around 170 feet when it should be about 220 feet as shown correctly by 910b along with the trace of the TDR indication starting before the left margin of the scale.
Does anyone else see this or know if there is some setting I am missing that might cause this? All settings in 910b, 915a and 916 are identical when this happens.
Thanks,
Joe W4WT
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Post by smokchsr on Sept 16, 2019 2:24:22 GMT -5
I haven't looked at that yet, But just in case be sure that you've double checked that your VOP (velocity of propagation) is set correctly in the new versions.
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Post by wa4sca on Feb 13, 2020 7:51:53 GMT -5
Was this ever resolved?
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k4ro
New Member
Posts: 5
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Post by k4ro on Apr 10, 2020 19:57:27 GMT -5
I am seeing the same behavior. TDR graph is shifted to the left, rendering the scale useless.
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k4ro
New Member
Posts: 5
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Post by k4ro on Apr 10, 2020 20:00:39 GMT -5
And yes, I checked that the velocity factor was set correctly.
Happens in standard and high resolution mode.
Is the only solution to revert to an earlier version?
--Kirk K4RO
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Post by wa4sca on Jun 6, 2021 12:30:26 GMT -5
Unfortunately, the problem still exists in version 925. It seems to be roughly a constant offset of about 2 feet, so for most applications, that will get you close enough. However, as it once worked, it is disappointing that you need to do this.
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Post by smokchsr on Aug 16, 2021 13:23:06 GMT -5
Well, I don't know what I'm doing right or wrong, I just ran a quick test V910a Vs V925 and got the exact same results between the 2. 22.41' for each in TDR mode at .88 VOP and using a front jack std cal that originated in that respective version. I also tried using an old Std Cal file from V910a in V925 and again 22.41'
I did see a difference in V910a when I was scanning a junk piece of RG8 at .66 VOP, V910 showed the line Z starting way high at 0' and climbing from there 925 came up with something that looked more like a piece of coax, but also showed higher and very unstable Z. That particular line has tested as junk in the past.
I guess one more test will be to compare the superflex on my Anritsu 331 (yes, I'm testing while typing)
best resolution with the Ritsu is 23' so all pretty much in agreement. I'll check again when I need to sweep some longer lines.
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