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TADD-1 RF Distribution Amplifier

The TADD-1 is a six channel RF distribution amplifier. Its primary use is to allow a single frequency source (e.g., a GPS disciplined oscillator) to drive the "external reference" input of several test instruments. The usable frequency range is 200kHz to 30MHz, and the maximum signal output level into 50 ohms is 2.75 volts peak-to-peak, or about 12dBm. The maximum high- impedance output is 5 volts peak-to-peak.

To minimize ground loops in sensitive test applications, the input and each of the six outputs is transformer coupled and DC blocked. RF connectors are ground-isolated BNC. A jumper allows the input to be terminated in 50 ohms, or to present a high impedance.

An optional bandpass filter can be installed to reduce spurious responses. Because of the various center frequencies and filter designs that might be desired, TAPR does not offer the filter components. Also, installing the filter may result in reduced phase stability over temperature changes, so we recommend that the filter not be used unless it is really needed.

Typical phase noise performance is -140dBc (1Hz) at >1Hz offset.

The 12 volt power input is fused and protected against reverse polarity. Current drain depends on the number of loads and ranges from 50 to 150ma.

The RF and DC inputs are arranged so that two (or more) TADD-1 boards can be stacked, sharing common RF and DC inputs.

Ordering Information

The price for the TADD-1 is:

  • $ 107 US for members of TAPR

  • $ 119 US for non-members

    + shipping/handling if applicable.
(Place Web Order)

A note regarding email addresses: When checking out please use an email address other than @earthlink.net, @hotmail.com, @live.com, @msn.com, @outlook.com. For some reason these domains reject email from tapr.org

Shipping and Handling

Shipping and Handling within the US will be by USPS Priority Mail.

International shipping costs are calculated as closely as possible. If the actual cost exceeds the estimate by more than $10.00, TAPR will contact you to get approval for the additional funds. TAPR uses insured Priority Mail International, unless the purchaser requires something else.

Assembly and Operations Manual

The assembly and operations manual can be found online at http://www.tapr.org/~n8ur/TADD-1_Manual.pdf.


TAPR kits can be complex depending on the kitting experience of each builder. We don't think you will have trouble with the kit, but it does require some knowledge and experience to successfully go from a kit to a finished, usable unit, depending on the mode of operations.


The TAPR TADD-1 Kit was made possible by the efforts of:

John Ackermann, N8UR – Designer and Project Manager

Joe Borovetz, WA5VMS – Parts Liaison
Tom Van Baak – Performance Evaluation
Bob Leuchtner, WO6W – PCB Design Assistance

Beta Testers:
Tom Holmes, N8ZM
Daun Yeagley, N8ASB
Mike Suhar, WB8GXB
Bob Leuchtner, WO6W
Mike Feher, N4FS
Carl Walker, WA1RAJ
John Miles, KE5FX

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