[time-nuts] RF transformers for distribution amplifier

Bruce Griffiths bruce.griffiths at xtra.co.nz
Tue Dec 16 20:09:56 UTC 2008


Yuri

1v pp into 50 ohm shouldn't be near transformer saturation.
If the transformer dc current is too high distortion will increase
significantly.
Seeing you have so many, you can afford to test one of them to
destruction should that eventuate.
Just drive it from a suitable source with a series resistor and /or
attenuator to set the drive level and look at the output.
Use an oscilloscope and/or spectrum analyser if you have them.

Bruce

Robert Atkinson wrote:
> Hi Yuri,
> I don't know about thr transformers you have, but a useful source of a very usable triple 1:1 50R transformer is an old 10base2 Ethernet card (the type with a BNC) these cards have a standard design that calls for isolation. They also yield a 5 (or 12) volt to 9V isolated DC-DC converter.
> Robert G8RPI.
>
> --- On Tue, 16/12/08, Yuri Ostry <yuri at ostry.ru> wrote:
>
> From: Yuri Ostry <yuri at ostry.ru>
> Subject: [time-nuts] RF transformers for distribution amplifier
> To: time-nuts at febo.com
> Date: Tuesday, 16 December, 2008, 11:27 AM
>
> Hello,
>
> Just digged in my junkbox(es) in hope to find something to quickly
> build distribution amp for Rb module that I just received from
> fluke.l. Figured out that I'm pretty short in fast opamps, but found
> considerable quantity of Mini-Circuits TC1-6-75-1 SMT wideband
> transformers (same as sold now by someone on eBay for US $17.49 for
> lot of 200 as item #110259000213).
>
> Here is some more detailed specs that good people from Mini-Circuits
> provided a year or so ago....
>
>   
>> The P/N TC1-6-75-1 is a Mini-Circuits custom design for one of our
>> cust's. However, this model was made available for other customers
>> as well.
>>
>> The specs are as follow:
>> Frequency:  5 - 50 MHz
>> Impedance ratio:  1:1
>> Impedance:  75 ohms nominal
>> Insertion Loss:  0.5 dB maximum
>> Input Return Loss:  14 dB typical
>> Maximum RF Input Power:  15 mW
>> Operating temperature:  0 to 70 degrees C
>>
>> All electrical specs measured with 0 mA DC current
>>
>> Case style:  AT224
>> Pinout:  (same as TC1-1)
>> Primary dot = pin 6
>> Primary = pin 4
>> Secondary dot = pin 1
>> Secondary = pin 3
>> Not used = pin 2
>>     
>
>
> I'm in doubt... I'd like to get about 1 volt p-p on a 50 ohm load from
> amplifier outputs, and it looks like that this transformer may be
> "overdriven" a little bit. Can it cause any serious problems?
>
>
>
>   




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