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Reviews For: Clifton Laboratories Z10040B Norton Preamp

Category: Receive Pre-amps

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Review Summary For : Clifton Laboratories Z10040B Norton Preamp
Reviews: 2MSRP: 47.50
The Z10040B is a kit (also available assembled and tested) implementing the Norton noiseless feedback amplifier, as originally developed by Dr. David Norton, and described at D. Norton and A. Podell, “Transistor Amplifier with Impedance Matching Transformer,” U.S. Patent 3,891,934, June 1975.
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
NA4U Rating: 2011-02-28
Great Value Time Owned: 0 to 3 months.
Well designed push-pull Norton HF+ receive amp, easy to build, excellent instructions, easy to setup, front-end protected, reverse voltage protected, gain set at build time, stable, provision for PTT transmit protection. Worked first time and does the job of providing boosted signals for my SDR while protecting the expensive A/D SDR front-end. Wide dynamic range, plenty of gain, high intercept point, low noise floor, very level gain, very low distortion. If you remove the amp's power during transmit, the amp's internal relay will place the receive antenna across 50 ohms and short the amps input. You can produce almost 1W out if you do not use this feature. Clifton Labs owner, Jack promptly answered my questions. The enclosures comes pre-drilled with all the hardware and connection support items. All-in-all a great and useful kit.
WZ7I Rating: 2009-11-12
Excellent Product Time Owned: 0 to 3 months.
My guess is that sometimes receive preamps in HF applications do more harm than good. But I recently purchased a QS1R SDR receiver to run Skimmer Server and Phil does not have the rf front end board for the receiver in production yet. Consequently the sensitivity of the receiver needed a little help with my vertical antenna and 200 feet of old coax. I wanted the cleanest preamp I could find and since there is no front end filtering, I didn't want the broadcast band to cause the receiver to clip. This preamp appears to work very well with this application. The amp can be built for various gain levels by changing the ratio of turns in the transformer. The default is 10.5 db.

This unit follows the suggestions of Dallas Lankford who has thought long and hard about such circuits:

A discussion of the theory of Norton amps, good documentation of its performance, and the complete manual are all available at the Clifton Laboratory web site. And Jack, K8ZOA, is a joy to work with.