James R. Gorr said the following on 02/18/2008 12:18 PM:

I use the 8140T line taps without an 8140 unit.  All they require is a
+12V DC signal riding along with the 10 MHz sine wave.  You can string a
bunch of taps off one reasonably strong source.

I have an HP 5065A Rb that I slightly modified to tap the 10 MHz off
from the internal 10811A oscillator before the divide-by-2 circuit*, and
putting a 12 volt DC bias on the signal (with an isolating capacitor to
protect the rest of the 5065A from the DC, of course).  I feed about 10
of the 8140T taps from this line, and it works well.

The 8140T amps have only decent phase noise performance; I wouldn't use
one for a demanding application, but this string running around the lab
makes it awfully convenient to grab a 10 MHz source wherever I need one.

One thing -- you want to put a DC-isolated 50 ohm load at the end of the
string to terminate the line.  I believe the 8140 amp unit has a fault
detector that will trip if it doesn't see that load, and it's good
practice to properly terminate the line, anyway.

John

Jamie,

If you have the Spectracom 8140 you need to use the line taps.  With out
using the line taps you sinewave will not be symmetrically along 0 voltage,
that is the sine wave will all be positive voltage.

The line taps were available in 10 MHz, 5 MHz, 1 MHz and 0.1MHz.;  what that
means, if your distribution amp is outputting 10 MHz and you use either  of
the above line taps you will receive the line tap stated frequency.  In this
way you can have a variety of output signals available to use for different
applications.  Spectracom has the manual for the 8140 available for a free
download on their website.
www.spectracomcorp.com/ go to; library; downloads; manuals

These are great and very versatile distribution amps.

ps check your amp for installed options and refer to the manual

Jeff

------- Original Message -----
From: "James R. Gorr" n3toy@yahoo.com
To: time-nuts@febo.com
Sent: Monday, February 18, 2008 12:18 PM
Subject: [time-nuts] spectracom line taps

jshank said the following on 02/18/2008 03:05 PM:

I'm not certain about that; while I haven't used an 8140 amplifier, I
have an 8164 WWVB disciplined oscillator that has an option installed to
allow it to run a string of 8140T taps.  I was able to use those outputs
directly by using a series cap to isolate the DC voltage; what's left is
the 10 MHz sine wave.  As I noted in my other post, it does want to see
a 50 ohm load (after the isolating cap) or the fault indicator may go
on.  I suspect the 8140 amp is very similar; Spectracom did a lot of
design reuse across their products.

John

John Ackermann N8UR wrote:

Be careful with that termination. If the  output has 12 volts DC you
would need an isolating cap.
The Line Taps were intended for a production line where the taps could
just be plugged in
and would get their power from the coax. Some were made that had a power
jack and those
could be powered from a "wall transformer".

Bill K7NOM

OK, well it looks like the taps are needed for the
proper operation of this device.  I will just get a
TADD1.  Thanks for the input.

--- Bill Janssen billj@ieee.org wrote:

https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

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