[time-nuts] high rev isolation amps

Magnus Danielson magnus at rubidium.dyndns.org
Mon Mar 28 09:55:28 EDT 2016


Hi John,

This would indeed be interesting.

I would assume that one would like to have shielded boxes for these.

Cheers,
Magnus

On 03/27/2016 04:33 AM, John Ackermann N8UR wrote:
> In light of this discussion, I'm taking a deep gulp to mention a project
> that's finished but has been on my back burner for a while.
>
> A few years ago I laid out a high isolation, low noise buffer amp based
> on one of Bruce's cascaded-transistor designs.  Isolation was measured
> in excess of 100dB with PN floor around -170dBc/Hz.  The frequency range
> is 1 MHz to 30 MHz and gain can be set from -10 to +7 dB.  It's designed
> for 18VDC input but will work at 13.8, with less headroom.  At 18V it
> can put out close to +20dBm.  It's a 1.75 x 3.75 inch board using SMT
> parts (nothing tiny, but *lots* of passives -- about 80 parts total).
>
> The board is ready to go, but I wasn't sure if there would be enough
> interest to justify production.  Given the tedious surface mount
> assembly, I assumed that there wouldn't be much interest in a kit, and
> an assembly run requires at least 50, and preferably 100, units to get a
> reasonable price.  At 100 units, I hope the price for an assembled board
> could be below $100, but no guarantees.
>
> If there is enough interest, TAPR could consider doing a production run.
>   If not, I'll release the design package including Gerbers.
>
> I'll try to get some better documentation put together in the next week
> or two, and figure out a way to create a sign-up list for people who are
> interested.  We'd have to have a minimum number of committed orders
> before kicking things off.
>
> John
> ----
>
> On 03/26/2016 08:24 PM, jimlux wrote:
>> On 3/26/16 4:14 PM, Richard (Rick) Karlquist wrote:
>>> Nothing has come to my attention in the last
>>> 35 years that is superior for buffer amplifiers
>>> to the simple cascade of grounded base transistors
>>> as described by numerous NBS/NIST papers.
>>> The chain usually starts with a common emitter
>>> (with emitter degeneration resistor), which
>>> is an even older NBS classic.
>>>
>>> I realize you asked for an OTS connectorized
>>> version.  Unfortunately, I have never seen
>>> one of these offered in said 35 years.
>>
>> Yeah, i've spent a while looking through various catalogs..
>>
>> Odd that nobody sells one: sure, it's probably a limited market, but
>> there's plenty of companies that sell limited market widgets (e.g. I'm
>> surprised Wenzel doesn't sell one.. in the online catalog info, they
>> don't even give S12 data of any kind)
>>
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


More information about the time-nuts mailing list