[time-nuts] Any reason not to use one power amplifier and splitter for distribution amplifier?

Joseph Gray jgray at zianet.com
Sun Jan 4 00:32:28 EST 2015

My 2 cents. I just repurposed an RGB video distribution amp for use
with a rubidium. The board has three EL2070 (200 MHz BW) amps, each
one feeds several BNC jacks for RGB output. I only need three
separate, isolated outputs, so I am feeding the rubidium into all
three EL2070's and only taking one output from each chip, via an
isolation transformer.

This seems to be working just fine for my intended purpose. I still
need to add the DDS and a few other items to the box to complete the

Joe Gray

On Sat, Jan 3, 2015 at 8:37 PM, paul swed <paulswedb at gmail.com> wrote:
> Dave
> I am sure there will be many answers. But yes indeed it will work fine. All
> of the outputs should have the same delay also and that may be useful.
> There really are the two approaches. The big power amp thats a 1/2 Watt you
> are talking and the many small amps as in the distributed mode.
> Whats interesting is the telcos always do the big amp splitter and the test
> equipment manufactures use precision distributed distribution amps. I guess
> its a pick your poison. Or maybe the test equipment manufacturers needed
> more isolation port to port. Or heavens maybe they could just sell them for
> more money. Would they do that?
> Humor aside each has a very good reason for doing the distribution and its
> driven by the requirements.
> I have several of those spitters and picked them up for $ 0 at hamfests.
> Seems no one had a use for them when all of the 900 Mhz gear came out of
> the sites. Mostly gone at this point. A 1/2 watt 10 Mhz amp is not that
> hard to build look at the many Ham sites we have a band close to 10 Mhz/ 30
> Meter.
> Regards
> Paul
> On Sat, Jan 3, 2015 at 6:09 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkirkby at kirkbymicrowave.co.uk> wrote:
>> I was looking to make a 10 MHz distribution amp to feed test equipment with
>> the output of a GPSDO.
>> I see this
>> http://m.ebay.com/itm/201244302355
>> 16-way Minicircuits splitter on eBay which I got for $40. I guess the loss
>> is around 12 dB.
>> I actually bought another for $35 which was similar but  one of them, the
>> isolation data made no sense,  so given their low cost I just bought both.
>> I suspect internally these 16 way units might have a pair of 8 way dividers
>> as there are two isolation figures,  depending on what ports one is
>> measuring between
>> Is there any reason not to just drive that with 22 dBm or so of power to
>> get 10 dBm at each of 16 ports?
>> Is 10 dBm an optimal value?
>> I see several distribution amp designs witb one amplifier on each output,
>> but is it just a lot less hassle to split a higher power amp.
>> I have a range of Minicircuits amps in my junk box in little enclosures,
>> which means a distribution amp can be built from just 3 main components
>> * PSU
>> * Power amplifier
>> * 16 way splitter.
>> That seems a *lot* simpler than many designs I see.
>> I was looking to feed it with an HP 58503A or similar device.
>> I do have an amplifier in my junk box which will produce 27 dBm. If I
>> combined that with 16 x 5 dB attenuators I could improve the isolation by
>> 10 dB, but I am unlikely to find the attenuators cheaply, and buying new
>> would add at least $200-$300 to the price, for what I suspect is no
>> significant benefit.
>> Dave
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