For this application you'll need a bandwidth of somewhat more than 10MHz
to preserve the clock slew rate.
Those transformers are better suited to sinewave operation at 5 or 10MHz.
If one uses a pair of transformers (one for the feedback and one to
isolate the output) then wider bandwidth 1:1 transformers can be used.
Or one could just elect to capacitively couple the load.
Alternatively one can just wind one's own trifilar transformer using a
suitable binocular ferrite core.
Bruce
Henry Hallam wrote:
The spec sheet lists them as being good to 10MHz; would they be ok at
16MHz with a little more loss, or should I worry about resonances with
parasitic capacitance?
73 de Henry M0HMH in Santa Cruz
On Wed, Aug 4, 2010 at 9:14 PM,<k6...@comcast.net> wrote:
I think I'm a time-nut; as symptoms I include (1) a lot of Mini-Circuits parts
on my bench, (2) searches on eBay for Mini-Circuits goodies, and (3) the desire
to know how my LPRO, 10811, and Thunderbolt are different, and how much better
a Thunderbolt would be with a 10811 double-oven in it...
Anyway, here's an eBay auction for 25 T-626 1:1:1 transformers -- item number:
220544907085
http://cgi.ebay.com/25-Mini-Circuits-T-626-RF-Transformers-0-01-10-MHz-/220544907085?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item335980374d
which look like just the thing for this amp...
73 de bob k6rtm in silicon valley
-------------------------
Message: 4
Date: Thu, 05 Aug 2010 10:05:39 +1200
From: Bruce Griffiths<bruce.griffi...@xtra.co.nz>
Subject: Re: [time-nuts] Buffer / distribution amplifier for TCXO
To: Discussion of precise time and frequency measurement
<time-nuts@febo.com>
Message-ID:<4c59e433.6000...@xtra.co.nz>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
Bruce Griffiths wrote:
In which case a linear distribution amplifier is probably required.
With only a ~3V supply available, options for the distribution
amplifier topology are somewhat limited.
In principle you could use an emitter follower driving 4 other emitter
followers with a resistor in series with the emitters of the output
devices and the AC coupled loads to match the source to the
interconnecting cable impedance to minimise reflections without
requiring excessive dissipation in the emitter followers.
With the low voltage supply available, using an RF choke is series
with the emitter follower's emitter to ground resistor will also be
useful in achieving the required dynamic range.
Bruce
A more efficient buffer amplifier circuit schematic is attached.
The series transformer feedback stage has high input impedance and an
output impedance matched to the transmission line (yes it works well
with long transmission lines as well).
However a trifilar wound RF transformer is required.
In principle the various GPS receivers could be connected to taps along
an end terminated transmission line using feedthrough connections with
compensation for the tap shunt capacitance if necessary.
A lower impedance line (eg 50 ohms) could also be driven at the expense
of a higher collector current.
In this case the value of R3 would need to be reduced to around 100 ohms
or so.
Bruce
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