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TADD-3 Pulse-per-Second Distribution Amplifier

The TADD-3 is a distribution amplifier for digital pulses. Its primary use is to distribute 1 pulse-per-second ("PPS") signals such as those obtained from GPS timing receivers.

The TADD-3 has six low-impedance outputs that deliver greater than 3.5 volts into a 50 ohm load, with rise time at the connector of less than 3ns. It also has two RS-232 level outputs that can be used to feed computer timing applications.

These outputs can be driven from one or two inputs, and the output polarity of each channel can be independently set. A multi-purpose input circuit allows direct input of TTL level signals, or other levels via an adjustable high-speed comparator. The inputs can be terminated in 50 ohm, 4.7kohm, or 1mohm loads.

The 12 volt power input is fused and protected against reverse polarity. Current drain depends on the number of loads and ranges from 70 to 250ma.

The RF and DC inputs are arranged so that two (or more) TADD-3 boards can be stacked, sharing common signal and DC inputs.

Ordering Information

The price for the TADD-3 is:

  • $ 71 US for members of TAPR

  • $ 79 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-3_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-3 Kit was made possible by the efforts of:

John Ackermann, N8UR – Designer and Project Manager

Joe Borovetz, WA5VMS – Parts Liaison

Beta Testers:
Poul-Henning Kamp

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