[time-nuts] GPS ant info

[Randy Warner]

Rob et al,

Be careful with the VIC-100 gain spec. When Aromat originally designed it
for HP back in the late 90's, they assigned the 30dB spec as an "absolutely,
positively, under any circumstances, will never be lower" number. The VIC's
actually run in the 38-40dB range. When I was working at Synergy we
complained numerous times about the number because it was so far from
reality. We had numerous cases of receivers being overloaded due to the spec
being so far off. This was especially true of the old VP timing receivers as
these would start to saturate at around +26dB of external gain (LNA gain
minus cable losses).

For example, using the stated numbers, using the 30dB number running into a
cable with 8dB of loss would result in a net 22dB to the VP, which is
perfect. However, a 38dB antenna with a -8dB cable would result in a net
+30dB at the front end of the VP. With this external gain the VP would most
likely be VERY unhappy. You guys running the old Odetics/HP/Symmetricom
timing boxes should keep this in mind.

This can be hard to troubleshoot as the symptoms of overdrive look much the
same as the symptoms of too little signal: low C/No's, satellites dropping
in and out of sync, etc. In the case of the VP, it will just stop tracking
anything.

Note on the new Panasonic VIC-100 datasheet that they changed the spec to
38dB typical.

Randy
_________________________________________________________________________

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Rob Kimberley
Sent: Tuesday, March 06, 2007 12:31 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] GPS ant info

Zyfer (formerly Odetics) use the VIC-100 antenna. Has about 30dB gain, 3
pole filter and works well in noisy environments. 

Using 4 of them right now, inside my office - single storey extension - flat
concrete roof, with them all next to each other strapped to the inside wall
approx 6 inches from ceiling (no external access just yet!). Tracking
several satellites on each on the two CommSyncs I'm testing. 

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Didier Juges
Sent: 06 March 2007 02:17
To: randy at geodetics.com; Discussion of precise time and frequency
measurement
Subject: Re: [time-nuts] GPS ant info

These specs are about the same as the 58532A from Symmetricom. I bought mine
on eBay, new in original packaging for $50, a short while later someone sold
a bunch of them (these may not have been new) for $15 to $20 a piece.

Anyone has compared them in actual operation or performance?

Didier KO4BB


Randy Warner wrote:
> Guys,
>
>  
>
> The CCAH32ST01 is the P/N for the TNC connector version of the Aromat 
> model VIC-100 timing antenna. Aromat is owned by Matsushita, who is 
> owned by Panasonic, etc., etc., etc. Panasonic has decided to put 
> their own name on things, so the new ones are identified as being 
> Panasonic. You can find a better datasheet on the US website here:
> http://www.pewa.panasonic.com/emp/products/gps_pdf/Panasonic_VIC100_An
> tenna_
> 9_06.pdf
>
>  
>
> Anyway, the VIC-100 is THE timing antenna if you are looking for top 
> performance. It is the standard antenna for Lucent, Motorola, and 
> everyone else.
>
>  
>
> Typical specs:
>
>  
>
> LNA Gain:   38dB
>
> Bandpass:   -60dB at fo +/- 50MHz
>
> Power:      +5V at approx. 25mA
>
>  
>
> As you might guess, its main claim to fame is the -60dB filtering. 
> It's about the only "standard" GPS antenna with three ceramic filters 
> (L1 ceramic filters as used in GPS antennas are typically good for 
> about -20dB at +/-50 MHz around foo).
>
>  
>
> When I worked at Synergy these were about $120. If you try to buy one 
> from Symmetricom it will set you back about $450. By way of 
> comparison, the Moto Timing2000 (with a dual ceramic filter) is about 
> $65. In short, you have one of the best timing antennas out there. Hold
onto it.
>
>  
>
> Randy Warner
>
> ______________


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