[Boatanchors] Drake cable question (measured)

[Ron Bussiere via Boatanchors]

 Hi Richard, no,it doesn't measure df. I used extreme care dressing the VERY short leads from the Leader to the cable under test. I repeated the tests multiple times. I use this bridge to measure ePay, er, eBay variable caps for the new VHF linears I am building (someday) ha ha

I have used this bridge hundreds of times and measuring the RG-6 was the only time I have ever seen this broad null. The 'tuning knob' is a 10 turn pot and it's easy to find a normal cap's value.Normally, the 'dip' is extremely sharp.......It went back to Leader a couple of years ago due to trying to measure the value of an 'orange drop'... Long story, but funny and expensive!!!

I don't know what to say... I'm sorry about the results. I should have used a different format. What I typed in is NOT what came out!

It's worth everything you'all paid for it.... ha ha

ron
N4UE

 

 

-----Original Message-----
From: Richard Knoppow <1oldlens1 at ix.netcom.com>
To: bonddaleena <bonddaleena at aol.com>
Sent: Tue, Jun 10, 2014 12:15 am
Subject: Re: [Boatanchors] Drake cable question (measured)



----- Original Message ----- 
From: "Ron Bussiere via Boatanchors" 
<boatanchors at mailman.qth.net>
To: <k4oah at mindspring.com>; <boatanchors at mailman.qth.net>
Sent: Monday, June 09, 2014 2:34 PM
Subject: Re: [Boatanchors] Drake cable question (measured)


>
> Thank you Garey. As usual, you know your Drakes. Although 
> I have been told I'm 'wasting' my time, it's my time and I 
> made the following measurements using a Leader LCR bridge 
> which was calibrated at Leader tracable to NIST standards. 
> The results were verified with both a Boonton Lab Quality 
> C Meter and a handheld Cap tool.
> The cables were cut to 36.5 inches (just as a 'standard) 
> and the extra 1/2 inch was prepped identically before 
> connecting to the bridge.
> This was 100% repeatable.
>
> RG-8X (shielded)        spec = 25.0 pf/foot     measured = 
> 25 pf/foot
> RG-59 (shielded)        spec = 17.3 pf/foot     measured = 
> 16.3 pf/foot
> RG-58U                     spec = 28.5 pf/foot    measured 
> = 29 pf/foot
> RG-6U                       spec = 20.5 pf/foot 
> measured = 18 pf/foot  *
> RG-62                       spec = 13.5 pf/foot 
> measured = 12 pf/foot
> Audio cable 
> measured = 23 pf/foot  (.100" OD)
> Phillips HDTV cable 
> measured = 16.6 pf/foot  **
>
> * = this is Direct TV cable and quad shielded, of course. 
> The notable thing about this cable is the fact the cap 
> bridge had a very wide null. All the other cables had a 
> very sharp null.
>
> ** = This cable has a clear covering, excellent braid, and 
> is very flexable. It is about the same size as RG-59. 
> However, this cable has 24 ct gold plated connectors. 
> Since it is very close to the good 'ole RG-62, this is 
> probably what I'll use for all the cables. I have some 
> gold RCA connectors to install as well. Gonna use minimal 
> cable length and align the R-4B/T-4XB twins with this 
> pick.
>
> Gotta love the 'bling'.........
>
> FWIW
>
> ron
> N4UE

     I am not familiar with the Leader bridge. When used for 
capacitance does it also measure dissipation factor?   I am 
asking because of the broad null. If the bridge has a 
balance for resistance as well as capacitance the broad null 
suggests there was some extraneous pickup.
     Did this show up on the other instruments?
     I think your measurements are valid but am curious for 
some details of the method.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com