[time-nuts] TBolt 10 MHz output ~1.7v rms / HP 8656B FG

[paul swed]

Max
I believe the inputs far more flexible then the limit suggested. Typically
the low level is the issue. In the spec sheet I see it says .15V.
If you had a 10 db anttenuator that would be a good start.
The good news is it sounds like you have enough signal to drive both things
pretty easily.
Regards
Paul.

On Mon, Jul 20, 2015 at 6:29 PM, M. George <m.matthew.george at gmail.com>
wrote:

> I picked up an HP 8656B from the usual place and have been cleaning it
> up... got around to testing the output which looks good on a cheap
> frequency counter etc...
>
> I'm wanting to use the 10 MHz output from my TBolt for the reference input
> on the HP 8656B and my Elecraft K3.  So I started digging around in the
> manuals I can find on the internet, including KO4BB's cool manual stash.
>
> I'm not finding the specs on the input for the reference on the 8656B.  I
> found an older reference for the 8646A that said to keep the input rms
> voltage between .2 and .4 volts, which scared me, because I had already
> hooked up the Tbolt direct.
>
> If this is correct, then .2 vrms - .4 vrms is around +2 dbm.
>
> The direct output on the TBolt to my scope is showing ~1.7 vrms which is
> close to +17 dbm.  Yikes, I had that hooked up to the 8656B for a while...
> I hope I didn't screw anything up.
>
> I have a K3 with the EXREF board hooked up direct to the TBolt and it's
> happy as a clam with the 1.7 vrms input.  Which is a tad bit high for the
> Elecraft docs which shows a nominal level of +4 dBm to +16 dBm.  I'm
> assuming the 1.7 vrms is falling in to the 'nominal' range.
>
> I'm not finding dire warnings about hooking the TBolt 10 MHz output direct
> to a K3EXREF or an HP FG...
>
> I don't have a frequency counter that takes an external reference (yet), so
> it's hard to know if the HP 8656B is using the external reference.  Again,
> I can't find much in the manuals to validate the external input, other than
> using a FC with the same reference input.
>
> Any input or tutoring would be helpful.  Are others just adding resistance
> in line with the TBolt output to drop voltage?  I tried a 50 ohm resistor
> and it dropped from 1.7 to just under 1v rms on the scope.
>
> Thanks
>
> Max NG7M
>
> --
> M. George
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