Improved Spectra-Strip Cable -- TPO insulation

[Gerard Visser <gvisser@indiana.edu>]

Hall D Electronics:

Hi,
	FYI - here (finally) is info on a possible improvement to the signal 
cable design. The cost is slightly higher, but the dielectric loss 
factor is about 30 times lower and almost certainly much more 
temperature stable. This would mean:
	- Increased signal swing into the ADC125 (and F1TDC for FDC anodes) 
modules, hence lower noise level and lower potential for interference 
pickup.
	- Much less temperature sensitivity. Yes the temperature of the cables 
in GlueX is not expected to vary more than a degree or two, but can 
anyone tell me today at what exact temperature the cable will be at? The 
equalization has to be designed for a particular temperature if PVC is used.
	- Most importantly, we have not yet addressed in any way the potential 
need for frequency equalization of the signal cables for FDC anodes, 
connecting the preamp/discriminator outputs to F1TDC boards. Dielectric 
loss in those cables will lead to a shift of effective propagation delay 
for the LVDS signal from discriminator to F1TDC if there was a 
preceeding pulse within ~1 us or so. This can probably be corrected 
offline, if the readout window is set large enough to see any precursors 
to the pulse of interest. Or some equalization could be incorporated in 
the new F1TDC. I don't think either of these things has been 
contemplated yet. If the dielectric loss is significantly lower, this 
whole issue may completely go away.
	I have asked (see below) for a sample of some similar cable if they 
have any... I hope so, then I will measure loss and report on it.
	If the cost is only 10% higher, and it does not impact the size, mass, 
or safety ratings, then I would think we should strongly consider to use 
the better TPO insulation.
	Fernando especially, please think about this and get back to me & Joe. 
It would be nice to make a timely response to Amphenol on this.
	Thanks,

		Gerard

-------- Original Message --------
Subject: Re: Spectra-Strip Cable
Date: Thu, 20 Mar 2008 15:35:52 -0400
From: Gerard Visser <gvisser@indiana.edu>
To: bdevaney@spectra-strip.com <bdevaney@spectra-strip.com>
CC: 'Joe Beaufait' <beaufait@jlab.org>, 'bwiggin' 
<bwiggin@spectra-strip.com>,	Mike Sigmon <msigmon@brandel-stephens.com>
References: <20080320182104.05F273A38AE@mta1.recol.net>

Hi Brien,
         This is indeed a significant improvement for not much cost. I will
discuss it with our group. I have two questions: First is, the UL rated
operating temperature (80 C) / current / voltage (150 V) and the fire
rating (CL2), are these all remaining the same if we switch to the new
insulation material? Secondly, do you have a sample of any sort of
twisted pair cable made with this TPO insulation?
         Thanks,

                 Gerard

Brien Devaney wrote:
> Gentlemen,
>
> Regarding the issue of a cable with a better quality dielectric material the
> factory has come up with the following cable design, P.N. 169-3099-784 which
> is built with a TPO insulating material. The TPO loss factor of .0006 at 1
> MHz and .0015 at 1 GHz is an improvement over the PVC cable, 169-3099-786
> previously supplied.
>
> If this is of interest to you we could build a 2,500' MOQ within 6-8 weeks
> ARO. Cost of this new cable is roughly 10% more than the current cable.
>
> Please let me know what you think.
>
> Sincerely,
>
> Brien Devaney
> Regional Manager
> Amphenol Spectra-Strip
> 978-365-9654