Hi If you: 1) Run a reasonable length of coax (say > 5 M and < 100M) 2) Neglect the 50 ohm termination You can get quite a bit of 10 MHz RF running around on the outside of the coax shield. Depending on grounding it may or may not be a problem.
The taps appear to deliver an ADEV of ~ 1x10^-11 at a tau of 1 second. That of course assumes the source you are driving into the system is better than that. They are designed to drive the standard input of a test instrument. There is processing (clean up) between the standard input and the instrument's clock. Most instruments you plug in will be quite happy with a signal that has that level of stability. Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of walter shawlee 2 Sent: Wednesday, July 27, 2011 3:00 PM To: time-nuts@febo.com Subject: [time-nuts] Spectracom 8140 distribution amplifier and the Taps- some application info There have been many questions posted here about the units, here are a few answers I have collected: 1. the 8140 can drive up to 25 total downstream 8410T taps on the combined outputs. The mopdels are frequency specific, and are not easily changed, 10Mhz is the most common. The front selector provides TTL divided waveforms from the input rear clock. 2. yes, the taps are needed, as the output of the 8140 itself is a sinewave and +12VDC. using the tap allows long cable distances, and provides the extracted, buffered sinewave. long cable runs of RG58 up to 500 feet are possible, with T-taps all along the way, and all 4 outputs can have long runs. the manual says a capactively coupled 50 ohm load is meant to terminate the line, but I have not found it to be required so far, as the sine wave drive produces very little ringing. 3. yes, it works WITHOUT the taps, if you add a 0.47uF good quality cap in series with each BNC output, run distance is then short into 50 ohms. 4. YES, taps are different, if you have a 10Mhz source, you must have 10Mhz taps (8410T10). beware of the 8410TTL10, it has a TTL 10 Mhz output, not a sinewave. 5. the operating quality of the system is excellent, do not be deterred by it's modest appearance, it works just as well as the racal, fluke and hp distribution amps I have and use. Late ones are much better made (they have black, not blue vinyl tops), if you can score one. 6. Phasing: my measurements show approximately a 190 degree phase difference between the input sine, and the output waveform at 10Mhz...not an issue for me, but maybe for others? 7. The system checks for DC output shorts (excessive loading) and loss of input clock, these drive the red front indicator (output fault). An option can also drive a sonalert. 8. the taps are not generally repairable, as they are potted with foam. bummer. 9. System details, and downloads are here at Spectracom: http://www.spectracomcorp.com/ProductsServices/TimingSynchronization/Timeand FrequencyDistribution/8140FrequencyDistributionSystem/tabid/133/Default.aspx 10. Note, there are no schematics for Taps, if anybody has some to send me, I'd really appreciate it, just to satisfy my curiosity. so, if you find one in good condition, it is a great addition to your lab, for distributing your master reference all around the shop area to counters, spectrum analyzers, generators, etc. it works with literally all common clock sources, from 0.3Vrms to 2Vrms, should be a sine wave. regards, walter Walter Shawlee 2, President - Sphere Research Corporation 3394 Sunnyside Road, Kelowna, B.C., CANADA V1Z 2V4 URL: http://www.sphere.bc.ca E-Mail: walt...@sphere.bc.ca Phone: +1 (250) 769-1834 Fax: +1 (250) 769-4106 --Home of the Slide Rule Universe-- WS2: If wishes were fishes, we'd all be covered in cod. WS2: We're all in one boat, no matter how it looks to you. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.