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 Post subject: Model CF Capacitor Exam-eter
PostPosted: Mar Sun 11, 2018 6:09 pm 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
A few years back someone ran across one of these testers missing the special “Quick Check” Test Probe. They were trying to reconstruct said probe and the consensus at the time was TV Twi Lead was a likely cable to use.

I now have one of these Exam-enters with the same Quick Check leads missing. Anyone recall the earlier discussion and whether or not a successful solution was achieved?

David


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Mar Sun 11, 2018 6:28 pm 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
The manual for this piece of equipment is matched by serial number to the set, F95426, and includes a later Supplement CF-412-1A when the company had moved to North Bergen, New Jersey.

There is a handwritten note on the front cover of the manual from somebody named ‘Jim’ that reads: “Leads are .00004 mfd”. I am wondering if this might be a reference to the Quick Check leads?

David


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Mar Mon 12, 2018 3:13 am 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 8768
Location: Long Island
I've got a CF Exam-Meter minus its leads which I have to get back on its feet too. But in the meantime I came across a Pyramid CRA-1 with its leads. It has a similar kind of "Quick Test" circuit. They were not as secretive about it as Solar was. The leads are made of ordinary 18-gage zip cord a little over 18" long. The zip cord is separated at the ends for the alligator clips and banana plugs, but there are metal bands at each end so the middle 15 inches cannot be separated. I suspect that separating the cord a certain length was how they "tuned" it. The metal bands prevented it from separating further which would throw it out of tune.

I think the "leads are 0.00004 mfd" is probably worth trying

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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Mar Mon 12, 2018 4:50 pm 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
Thanks for that information, Chris. I will assemble a set of leads based on your specs and see how they work. Will also look at trying to factor in “Jim’s” reference note and see what that does to things.

Solar must have closed up shop quite some time ago. Doesn’t seem to be any corporate information on them at all on the web.

David


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Mar Tue 13, 2018 12:26 am 
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Joined: Sep Mon 16, 2013 2:42 am
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Location: Tucson, Arizona U.S.A.
A short piece of heat shrink tubing around the zip cord is a good way to prevent the wires from separating.

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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Mar Wed 14, 2018 8:53 pm 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
Chris.

No rush, but could you post a photo of what your Pyramid leads look like?

David


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Jun Sun 16, 2019 2:58 pm 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
Been a while since I was looking at this tester but I have finally purchased appropriate banana plugs and alligator clips to fabricate a Quick Test set of leads. 18 ga red/black zip cord is on back order, so a few more days before I can effect an assembly.

In the meantime, while rereading the manual I finally noticed this interesting little accessory mentioned (photo from manual attached). The item does not show up in the parts listing in the manual so I am thinking this accessory might have been a third party product, rather than a Solar designed and built product. I wouldn't mind finding one one day. anyone ever run across one in real life?

David
VE4DTD


Attachments:
TYPE RT-3 Adjustable Test Fixture.jpg
TYPE RT-3 Adjustable Test Fixture.jpg [ 242.42 KiB | Viewed 606 times ]
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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Jun Sun 16, 2019 3:11 pm 
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Joined: May Wed 18, 2011 2:40 am
Posts: 4150
Location: Littleton, MA
I've never seen an adjustable test fixture like the RT-3, but Grayhill makes test clips that can be used to fashion one yourself:
http://www.grayhill.com/assets/1/7/test_clips_term.pdf
Attachment:
grayhill-test-clips.png
grayhill-test-clips.png [ 157.97 KiB | Viewed 604 times ]

They are readily available from distributors such as Allied Electronics and DigiKey.

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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Jun Sun 16, 2019 6:06 pm 
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Joined: Jan Tue 10, 2012 8:39 am
Posts: 645
Those clips are nice and I have several. But they are ridiculously expensive. Perhaps better to modify a dual banana plug.

Short leads are essential for measurements of low value capacitors, especially below around 200 pF. A rule of thumb is that every inch of lead adds around 2 pF to the measurement. And balance the bridge with nothing connected to see the residual.

I have had a few of these over the years. I now have an EICO 950B but I will never use it, as I have much better instruments.

For measurements above around 20 pF you can buy one of the cheap Chinese testers that also tests resistors and semiconductors and inductors and they go for only a few dollars. Google Mega328 I think it is, on ebay.

The one thing the old units do is test electrolytic capacitor leakage. They don't measure it; they arbitrarily use the leakage current to drive an eye tube for a qualitative measurement. A better way is to measure current yourself while applying voltage. You have two problems with that - you have to protect against shorts and you have to decide how much leakage you are willing to tolerate. Leakage is less important in itself than its indication of the potential life of a unit. Leakage that gets worse while voltage is applied is a bad thing. And compute the power loss to decide if thermal runaway might happen. One Watt loss is too much.


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Jun Mon 17, 2019 12:43 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5027
Location: Sunbury, Ohio 43074
I've got a CF, and a CE. I'm now inspired to restore them. In line, behind a few other things. (probably 100)

still looking for an apprentice lmao

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Preserving the hist. of electronics, one boat anchor at a time! :)
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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Aug Mon 12, 2019 3:22 am 
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Joined: Jul Tue 22, 2008 6:12 pm
Posts: 98
Location: Winnipeg, Canada
I finally got the 18-ga zip cord and have started in on this project.

Annoyingly, however, on lifting the unit off the shelf, the leather carry strap on top of the case snapped in half. I recall seeing replacement leather straps of various shapes and sizes on a company website a few yeas ago but cannot relocate it now. Does anyone know who might carry replacement leather straps these days?

David
VE4DTD


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Aug Mon 12, 2019 3:41 am 
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Joined: May Wed 18, 2011 2:40 am
Posts: 4150
Location: Littleton, MA
David Dunlop wrote:
Does anyone know who might carry replacement leather straps these days?

Brettuns Village:
https://www.brettunsvillage.com/trunks/ ... s/handles/
https://www.brettunsvillage.com/trunks/ ... schandles/

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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Aug Mon 12, 2019 11:35 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5027
Location: Sunbury, Ohio 43074
BE CAREFUL with old leather straps. I've had one or two break as well, but fortunately have not dropped any equipment yet. I try and make it a practice to NEVER lift something by it's 80 year old leather handle. ;-). .... But sometimes one gets in a hurry. I hope the one I drop some day won't be irreplaceable....

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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: Model CF Capacitor Exam-eter
PostPosted: Aug Tue 13, 2019 2:31 am 
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Joined: Sep Mon 16, 2013 2:42 am
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Location: Tucson, Arizona U.S.A.
Try a luggage repair shop. Take the old handle and the instrument with you to check for fit. They may have something the right size but it may be a different style.

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Jim Mueller


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 Post subject: Re: Model CF Capacitor Exam-eter
PostPosted: Aug Tue 13, 2019 2:57 am 
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Joined: Nov Wed 30, 2016 7:35 pm
Posts: 5027
Location: Sunbury, Ohio 43074
Try the cabinet restoration forum here on ARF.... I seem to remember someone that can supply these for our hobby.

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


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