K3S K3EXREF 10MHz Voltage Help

[MaverickNH]

The manual says: http://www.elecraft.com/manual/E740156%20K3EXREF%20Installation%20and%20Operation%20Manual%20Rev%20A2.pdf
Connect the external 10 MHz signal source to the K3 rear panel REF connector
. The 10 MHz source should have a signal levelbetween +4 dBm and +16 dBm, nominal
. For square wave sources, 2VDC to 3.3VDC peak is optimum. If the source is a 5V logic level, use a 50-ohm resistor in series with the input.
Caution: To avoid damage to the K3EXREF, do not exceed these levels

My Jackson Labs LC-XO-Plus manual says: http://www.jackson-labs.com/assets/uploads/main/LC_XO-PLUS-specsheet1.pdf
Oscillator Specification: Frequency Output 10MHz CMOS 5Vpp

So I'm concluding the need for a 50ohm resister in series with the input.

The K3EXREF board will come pre-installed with my new K3S, so I'd prefer an exterior solution. Is there a tidy little SMA connector with 50ohm in series that I can get off the shelf? Or would I have to make that? If so, how to best do that? I can certainly chop a SMA(M)-SMA(M) jumper in half and solder a 50ohm resister across the center wire, but I'm not sure how to maintain the shielding ground web. Twist each side and solder, sure, but seems I lose shielding of a delicate signal.

Thanks for the help!

BRET/KC1CJN

[Edward R Cole]

Bret,

I run my 10-MHz reference thru a 4-way distribution amplifier that
has a two-pole bandpass filter which passes only a sine wave no
matter how distorted the source 10-MHz.  That provides 10mw level to
all my equipment needing a reference.

But if you are determined to provide some protection a 3-dB sma
attenuator should do just fine.  They are small in diameter and size
with typically sma-male and sma-female on opposite ends.

If there are some VHF-up hams in your area ask about getting one;
otherwise they are available on e-bay and from mfr's (Google "sma
attenuators").

73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
Dubus Mag business:
     [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]