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 Post subject: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 6:12 am 
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Joined: Nov Sat 14, 2020 6:31 pm
Posts: 82
Location: Okotoks
I have just bought this VTVM but it came without probes. I do have a bare RG connector though.

I have the manual but it doesn't show a probe.

Tons of probes on EBay but non specifically for my make and model.

Any advice would be appreciated


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 12:30 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Can we see a photo of the instrument ?

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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 3:46 pm 
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Joined: Jul Wed 22, 2009 3:07 pm
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According to the specs your VTVM has 10MOhm input resistance parallel with 25pF or 40pF capacitance (depending on range) and a 1MHz bandwidth.

A DIY probe with coax cable would be fine, or a passive 1x scope probe could be used.
Those probes would add about 70pF to 100pF to the input capacitance.

If in doubt do model the loading effect of the probe on the circuit measured.

Here is a Tek document about probes for scopes. This is relevant to VTVMs as well with the difference that scopes usually have a 1MOhm input impedance with some parallel capacitance and a lot higher bandwidth.
http://web.mit.edu/6.101/www/reference/ABCprobes_s.pdf

Regards, Peter


Last edited by orbanp on Jan Thu 07, 2021 8:57 pm, edited 1 time in total.

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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 5:36 pm 
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Joined: Nov Sat 14, 2020 6:31 pm
Posts: 82
Location: Okotoks
This is the probe I currently have which I believe is a passive probe. Has x10 and x1 so all I would need would be a BNC to UHF adaptor

Attachment:
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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 6:26 pm 
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Joined: Nov Sat 14, 2020 6:31 pm
Posts: 82
Location: Okotoks
Attachment:
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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 8:55 pm 
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Joined: Jul Wed 22, 2009 3:07 pm
Posts: 900
You are correct about just needing an adapter for using the scope probe.

The 10x setting could be useful too, in that case the input capacitance of the probe would be only about 10pF - 20pF.
Do look up the data sheet of your probe!
The 10x setting with the smaller input capacitance might make a difference, depending on the circuit measured.
The sensitivity would be about 0.5x instead of 0.1x, actually 10 / 19 = 0.526, a 10x probe has a 9 MOhm resistor in series.
Here is some more info on oscilloscope probes:
https://www.electronics-notes.com/articles/test-methods/oscilloscope/scope-probes.php
There would be no need to touch the compensation, it would not make much difference because of the limited bandwidth of the VTVM compared to a scope.

Regards, Peter


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 10:26 pm 
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Joined: Nov Sat 14, 2020 6:31 pm
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Location: Okotoks
Max input voltage on x1 is only 150V RMS and x10 300V RMS and the VTM has a 500 V RMS maximum.

Guess I need to find a higher voltage passive probe


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 10:39 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Or don’t exceed the probe voltage. :-)

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Preserving the hist. of electronics, one boat anchor at a time! :)
https://www.bbtvtestequipment.com


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Thu 07, 2021 11:10 pm 
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Joined: Nov Sat 14, 2020 6:31 pm
Posts: 82
Location: Okotoks
Well that's never going to happen :roll:


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Fri 08, 2021 4:08 am 
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Joined: Jun Sat 09, 2007 8:14 am
Posts: 4620
Location: Florida
Have you tried to zero the meter movement?

As mentioned in the manual, if you remove the RF connector you can use banana plugs for the input connections. I typically use loosely twisted pairs and alligator clips for this kind of meter.

RRM


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 Post subject: Re: Kikusui model 164 VTVM
PostPosted: Jan Fri 08, 2021 9:55 pm 
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Joined: Nov Sat 14, 2020 6:31 pm
Posts: 82
Location: Okotoks
Haven't done anything with it yet.
Going through a load of tubes testing them at this time

Gordon


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