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TDR CableScout Pulse Generator


March 15, 2013, Aurora, Oregon. The new TDR-CableScout is a unique new pulse generator for testing transmission lines from 50-600 ohms used by ham radio operators. Unlike expensive commercial TDR systems which include a dedicated display, the TDR-CableScout is an entirely new product. It is an accessory for your oscilloscope. It is a smart, very high speed pulse generator, with selectable TDR DUT impedances and integrated high speed samplers.

Since the TDR-CableScout has built-in samplers, no clumsy “T” connectors are required. This allows you to use your scope’s vertical amplifier in the fast 50 ohm input mode. If your scope does not have a 50 ohm vertical input, we can provide you with 50 ohm pass-through terminators for the highest resolution and speed. Just connect it to your scope with conventional 50 ohm cables and your transmission line or cable to the DUT port, and the TDR-CableScout interrogates your cable with either a Step TDR or Pulse TDR signal and provides vital information of transmissions line used by ham radio operators. No manual calculations are needed as the TDR-CableScout TDR computer provides measurement results right on it’s high contrast back-lit LCD.


  • Fast 150ps Tr pulse TDR generator
  • Built-in high speed scope samplers
  • Measure cable quality
  • Locate faults & bad connections
  • Measure cable losses
  • Computes reflection coefficient
  • Measures transmission line impedance
  • Measure VSWR/Return loss/Velocity factor and more

The TDR-CableScout comes in two models, the standard version and the pro version.

Price and availability to be announced separately

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Updated application note released

appnote logoApplication note entitled “Measuring Return Loss with an oscilloscope and a Return Loss Bridge (RLB)” has been completely re-written. We expanded and made corrections to this application note. There existed some confusion as to the definition of “return loss” particularly whether it is a positive or negative quantity. Also improved is the step-by-step procedure on how to measure return loss in every day ham radio applications.

We thank our customers who gave us their valuable time in providing us feedback. Without their help the improvements would have been more difficult. We encourage all our customers to contact me here at PreciseRF with their recommendations and any feedback which will improve our products. We advertise and support eHam and QRZ.  Reviews on either site will  help other hams select products for their ham radio activities.

Happy New Year,


Roger W1RMS


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NIST Calibration Certificate

preciserflabAll PreciseRF products are now available with an optional NIST calibration certificate. To add the NIST calibration certificate to your order, simply select the option from the drop down on the product page. The NIST calibration certificate is provided for users needing a calibration reference showing the actual performance achieved. This calibration is done using NIST traceable instruments. Some test and measurement equipment was calibrated at the PreciseRF laboratory using NIST traceable instruments. The item calibrated may be used as a calibration reference only, and shall not be used as a NIST calibration standard. This certificate shall not be reproduced without the express written permission from the calibration facility.

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PreciseRF at SEA-PAC 2012

Robert at SEA-PAC 2012
Robert at SEA-PAC 2012
Robert at SEA-PAC 2012

PreciseRF engineer, Robert Kirkpatrick of KI6HNA, stands ready for another demo of PreciseRF products at the Sea-PAC convention in Seaside, Oregon. Audrie Crane, in charge of sales at the convention, is pleased to report that interest in our products continues to grow with brisk sales to Ham Radio operators.

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PreciseRF to Exhibit at SEA-PAC June 1,2,3

all products-1b smallPreciseRF will exhibit its new product at the SEA-PAC convention in Seaside Oregon, June 1, 2, 3. Our team is looking forward to meeting all Ham Radio enthusiasts at the show. See all of new new products which are ideally suited to maximize your signal quality and RF output. To kick off our business, we have some really attractive deals for you.


Roger W1RMS

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PreciseRF open for business

The PresiseRF team is proud to announce opening the doors to our new business. Said Roger Stenbock “After a nearly a year of intense product development, production of inventory, (all in-house made in the USA), we are pleased that all the pieces, from product development, production of inventory, organizing and launching the eCommerce store, all came together.”

Immediately after opening our store, our first customer purchased the popular SMT-Pro Station Monitor. His order was placed on line. Success in starting a new business in the Ham Radio niche market is not guaranteed, and one always wonders what details might be overlooked. Fortunately, thanks to our dedicated team, the notification to sales, invoicing, and shipping occurred without a hitch.

A special thanks to Travis Cannon for his contribution. While not a ham (not yet),  Travis is an experienced computer scientist with the added benefit of his business expertise as an MBA.  He created the eCommerce store and provided us with marketing and business guidance so often overlooked by engineer types. Upon hearing of our fist sale Travis commented “Way to go team”

Also, we’d like to thank Rob Kirkpatrick KI6HNA, for his expertise in industrial design and ECB layout.  He is comfortable and very experienced with CAD tools. As a result, Rob was invaluable in creating and running the files on our CNC machine for our prototype boards. He reviewed the electrical design and asked the “what if” questions, keeping the design engineers honest. Rob’s philosophy is that quality must be designed into a product, and is much more difficult to achieve by testing alone. One of Rob’s favorite refrain “calculate twice, then check twice, then commit to the final design”  Good advice as virtually all our ECB boards passed muster on the first pass.

Production and sales manager Audrie Crane commented, “After spending months building inventory, this sale was really exciting and I look forward to working with Ham Radio customers to provide the best possible products and service”.


Roger W1RMS


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PreciseRF Discloses Invention

On November 29th 2011, the Unites States Patent and Trade Mark Office (USPTO) notified PreciseRF that it acknowledged receipt and disclosure of a new invention entitled ENVELOPE DETECTOR WITH RF POWERED BIASING CIRCUIT and accordingly, this new invention is entitled to patent protection under 35 U.S.C. 111,  including establishing the invention filing date and authorizing marking its products “PATENT PENDING”

In a statement, Roger M. Stenbock of W1RMS and chief engineer at PreciseRF, praised his team. “We take great pride in our engineering team’s innovation and look forward to include this invention in new products scheduled for introduction early 2012 serving the ham radio marketplace”

A brief overview of the specifications include:

The present invention relates to a system, method, and device for envelope detection with RF powered biasing circuits, and more specifically to passively detecting the envelope….


As will become apparent in the specifications, this method overcomes some of the limitations, such as significant base band inter modulation distortion 10 (IMD) products and errors in trapezoid and two-tone test analysis, inherent in un-biased envelope detectors at low signal levels. A detailed circuit description follows a discussion of the invention…

The method according to the present invention consists of a circuit that is an essential component of a station monitor which monitors RF transmitter emissions of amplitude modulation (AM), double side band (DSB) and single side band signals (SSB). It includes an RF sampler and envelope detector. It can be used for both QRP (low power) and QRO (high 5 power) operation. The station monitor allows for precise examination and tuning of the entire RF transmitter chain. This chain may include transceiver outputs ranging from about 0.1 to 100 Watts driving linear RF amplifiers. In addition to a wide band sampler, the station monitor includes a high performance demodulator, a variable base band output and an oscilloscope trigger output. This invention features a passive diode biasing circuit for detecting very low (QRP) transceiver envelope Levels.

NON-BIASED ENVELOPE DETECTORS: Low cost passive wide band demodulators employ an envelope detector. This detector is an electronic circuit that takes an RF signal as input and provides an output that contains the “envelope” of the original signal. Generally, a diode rectifies the incoming signal, allowing current flow in only one direction. Practical envelope detectors use either half-wave or full-wave rectification of the signal to convert the AC audio input into pulsed DC signals. Filtering is then used to smooth the final result. This filtering is rarely perfect and some “ripple” is likely to remain on the envelope output, particularly at low frequencies. More filtering gives a smoother result, but decreases the responsiveness; thus, real world designs must be optimized for the application.

LOW LEVEL DETECTION: Another undesirable characteristic is non-linearity of the detected base band. This is caused by the diode’s conduction voltage drop ranging from about 0.2 volt to 0.8 volt (forward bias voltage drop) depending on the diode type and current. In the forward bias voltage diminished conduction region the diode does not linearly detect.

For high level RF envelopes, this region usually represents only a small percentage of the envelope and can be ignored. However, in low level RF envelopes encountered with QRP operation, this region represents a considerable portion of the modulation envelope. As a result, the base band will exhibit significant non-linearity near the maximum modulation depth of the RF envelope.

One way to mitigate this undesirable characteristic is to bias the detector such that it is conducting throughout 100% of the modulation envelope. The present art effectively accomplished this by means of a precision current source using a separate power supply. Unfortunately this adds complexity and cost.

This invention overcomes these shortcomings by incorporating a novel way to achieve such bias current (100-500uA). The current is derived from the RF signal by a second detector, with a proprietary circuit (this invention) which is passive and does not require an external power source. This results in embodiment with lower cost and reduced complexity, wilts providing exceptional  base band linearity over a wide input range for precise transmitter amplifier performance measurements.