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New! Precision TDR Pulse Generator for Ham Radio features TDR computer with 150ps pulse Tr.

Aurora, Oregon, May 1, 2013. PreciseRF announced today that the new TDR-CableScout® will be introduced at the annual SEA-PAC Ham Convention May 31-June 2, 2013 at Seaside, Oregon tdr cablescout product photo 1024

The TDR-CableScout® gives Hams, with access to an oscilloscope, the means to analyze transmission lines and circuit board strip lines. Line impedance from 50 ohms to 600 ohms can by measured with 25 ps resolution.

TheTDR-CableScout® features isolated high speed samplers and separate device under test (DUT) outputs. This design allows a direct, fast Tr 50 ohm connection to the oscilloscope for accurate TDR measurements without the inconvenience and lower performance  of the “T” connector technique.

A transmission line library is included, it contains data for velocity factor (Vf), line impedance (Zo) and line loss data. The integrated TDR measurement computer takes the work out of TDR measurements, such as time to fault (TTF), reflection coefficient (p), cable length, velocity factor (VF), Line impedance (Zo), return loss (RL), SWR and cable loss.

The TDR-CableScout® has both pulse and step TDR TDR functions. The step TDR has a maximum range of 15 KM and time resolution is better than 1 ns. The pulse TDR features a 500 ps pulse width and 150ps Tr. The resolution is under 5mm, this is well suited for analyzing circuit board strip lines. A dedicated trigger output with a 100ns pre-trigger delay allows viewing of the TDR pulse leading edge when using sampling scopes without a delay line such as the 7S11 and 7T11 installed in legacy Tektronix 7000 scopes.

“While TDR transmission line testing is not new in the commercial communications industry, it has always been expensive and not in reach of the average ham. The new TDR-CableScout® will now help make TDR measurements affordable for ham radio operations,” said preciseRF CEO, Roger Stenbock W1RMS.

Two versions will be introduced, the standard version and the professional version. Options include a variable terminator for direct impedance measurements, expanded measurement firmware, and a bundled scope package featuring a 200 MHZ DSO, NIST calibration and extended warranty.

Pricing will be announced at the SEA-PAC convention.

PreciseRF is a leading developer and supplier of oscilloscope measurement accessories for ham radio operators, measurement industry and the U.S. Government, with production and sales located in Aurora, Oregon and product development and engineering in Placerville, California.

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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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Recommended Scopes

For HF measurements, a 50-100 MHZ scope will work very well. For two meter measurements a 200MHz scope is needed. We recommend portable scopes. They are simple and reliable and lower cost than bench top scopes. There are still some CRT scopes available new, but most manufacturers now produce only DSO (Digital Storage Oscilloscopes). While the CRT scopes are very easy to use, they do not provide for automatic measurements. However, they are well suited for many of the measurements ham radio operators need to make.


Our recommendation is the The Hantek 200 MHz DSO 5202B. It was especially selected for its high bandwidth, ease of use and suitability for ham radio measurements. We provide this scope in our packaged measurement offerings. It is a rugged reliable performer with a great user interface at an affordable price. By packaging this scope, you can save considerable money over buying the scope separately. This scope was especially selected for its high bandwidth, ease of use and suitability for TDR measurements. It is a great scope to have in your shack. It is well suited for use with our station monitors, two tone test generators, samplers, couplers and return loss bridges.


For those on a budget, older Tektronix scopes are available from on eBay. These scopes when new, costs thousands of dollars. They are very rugged and reliable.  Most of these scopes do not use a microprocessor and all controls are generally switches hard wired. These scopes can be had for bargain prices from $75 – $200. There are a number of service centers found on the internet which will repair and calibrate these scopes.

Tektronix model 465 100 MHz

Great scope! Produced by the thousands from the late sixties to the mid seventies. Considered by many the standard of portable CRT type scopes. They feature main and delayed time bases, excellent triggering, and very flat vertical amplifiers.







Tektronix model 475 200 MHz

High bandwidth version of the 465. Produced from the late sixties to the mid seventies. Used in high end computer service and some R&D applications. Will work well in HF and 2 meter measurements.




Tektronix model 2213/2215 60 MHz

Low cost, light weight, reliable. Used in the computer service industry and education. Produced from the mid seventies to late eighties. Uses ICs and discrete components, includes automatic intensity and TV triggering. The high efficiency switching power supply reduces weight and power consumption, although it can cause some low level noise to nearby receivers. Most control switches in the vertical and time base range setting are of the cam switch design, they are rugged and long lasting.





Tektronix model 2235/2236 100 MHz

Great scopes! The are a higher bandwidth version 2213 and 2215 models. They provide a high writing rate making low rep rate signal at fast sweep speed easier to view. They are characterized by low distortion and very flat vertical amplifiers. Also includes TV trigger and delayed sweep B triggering. Some even have digital volts, time and frequency measurement capability (2236). Produced from mid seventies to late eighties. They were and are still used in the high end digital service industries and some light R&D. These were considered the new standard following the model 465.


New scopes cost more. They provide very convenient automatic measurements. They are much lighter and thus more portable. Generally, sample rates should be greater than 1G samples. Many have FFT functions built in. This allows them to make frequency domain measurements and are handy as a poor man’s spectrum analyzer. They are available online and from the big electronic super stores. Both the Tektronix and the Rigol scopes are made in China.

The Tektronix version of the TDS 2000 series provides a lifetime warranty and NIST (National Institute of Standards and Technology) calibration certification. They also feature self calibration using internal amplitude and time standards.






Tektronix TDS2001C 50MHz – about $890

Tektronix TDS2012C 100MHz – about 1,300

Tektronix TDS2022C 200MHz – about 1,850







If you don’t need the NIST certification and guaranteed accuracy of the Tektronix scopes, the Rigol scopes provide the best new price and a similar feature set as the Tektronix scopes.

Rigol DS1052E 50MHz about $329

Rigol DS1102E 100MHz about $399

Rigol DS2202 200MHz about $1626



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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.

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Linearity upgrade introduced

A new low level detecter provides QRP (low power) demodulation with high linearity at 100% modulation levels. This unique bias scheme is entirely passive and does not require an external power source. This new circuit was developed by the design team at the W1RMS labs.