Yes, I have the same configuration. The part number for the divider
board is 05061-6165. The 10811 + daughter boards are used in the 105B,
5061B Cesium, and the 5065A Rubidium. The circuit loading problem is
exactly the kind of issue I was expecting. Thanks for the warning. I
could probably resolve it by replacing the existing 7474 with a 74HCT74,
but I'd like to minimize the amount of hacking I inflict upon the unit.
Ed
John Ackermann N8UR wrote:
I did something similar to my HP 5065A Rb standard, which had a 10811A
and a small plug-in card that was a digital IC doing a divide by two
followed by a simple LC filter. I picked off the signal right at the
chip input with a small cap and a piece of RG-174 that went to a
buffer amplifier (I used a two-channel prototype of the TADD-1 with a
MAX-477).
It works fine, except that you need to use pretty loose coupling to
avoid loading the signal down to the point that there's not enough for
the divider to trigger on.
I suspect the 105 (and later 5061As that used 10811s) use the same
divider card, and the same treatment would work.
John
----
Ed Palmer wrote:
I was thinking more along the lines of an analog buffer, but you make
a good point. And if I want a sine wave output, I could use a simple
pi filter to clean it up. I have an HP 8647A RF generator that does
exactly that on the 10 MHz reference output.
Thanks!
Ed
[email protected] wrote:
Ed,
I have seen a hex schmitt trigger inverter used for this.
The output of the OXCO goes into all 6 schmitt rigger inverter
inputs and then on the output side you have the output leg of each
inverter connected through 300 ohm resistance. Thusly you get 6 hex
schmitt trigger inverters wired in parallel and with a combined
output resistance of 50 ohms.
Very simple and might be just the thing you're looking for.
John
KB1FSX Sent via BlackBerry by AT&T
-----Original Message-----
From: Ed Palmer <[email protected]>
Date: Mon, 07 Dec 2009 11:03:51 To: Time Nuts Mailing
List<[email protected]>
Subject: [time-nuts] HP 105B Modification
I have a late-model 105B Oscillator that's equipped with a
10811-60109 oscillator. It seems a shame to have that nice 10 MHz
source without having access to it. I was thinking of adding a
buffer amp and bringing out the 10 MHz signal. It shouldn't be too
hard, but before I reinvent the wheel, has anyone done this and do
you have any suggestions or advice?
Thanks,
Ed
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