[time-nuts] TrueTime A-60FS antenna Data Needed

Normand Martel martelno at yahoo.com
Fri Jan 5 18:08:47 EST 2007


You could do a simple test:

With an ohmmeter, on Diode test and with reversed
polarity (Red on shield, black on center pin), measure
the DC resistance on the RF connector. If it's a short
(< 1 ohm) DO NOT APPLY ANY VOLTAGE ON IT! Your antenna
is passive and conducting.

If the ohmmeter indicates a diode reading (about 0.7V)
the antenna is active and some bias will be required
to have the antenna work.

If the reading is infinite, it is either a passive
(open) or active antenna.

To further determine the type of antenna, i suggest
you to use some length of coax (20-50ft) cable to put
the antenna away from you, and, using a regulated 5
volts power supply with a 1000 ohms SERIES resistor,
apply power (forward polarity, e.g. positive on center
pin) to the antenna and measure the voltage across the
1000 ohm resistor.

If you have some voltage across the resistor, this
indicates that the antenna preamplifier draws some
current and, obviously, the antenna is active. If no
voltage is present across the 1000 ohms resistor,
your antenna is passive.

Why the 20-50 foot coax? Simply to put some isolation 
between you and the antenna. If the preamplifier is
turned on by the 1000 ohms bias and the antenna is too
close from you, the whole thing will start to
oscillate.

73 de Normand VE2UM

--- Doug Millar <dougnhelen at moonlink.net> wrote:

> 			
> Hello,
> 	Hope the New Year is going well. I recently got the
> above antenna to 
> use on another receiver, but no data. Does anyone
> have a description 
> of the interface? Is it just a simple ferrite
> antenna, or does it 
> have a preamp and need bias, or "other" ?  Any info
> would be very helpful.
> 	Thanks,
> 	Doug K6JEY  
> 
> 
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>
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