Products, Sales and Manuals



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Treetop Circuits

Products, Sales and Manuals


LC-1 Active Probe System

This product was replaced by the LC-2 in July 2014.

LC-2 Active Probe System

$345 US plus shipping
This is a versatile 1-GHz active probe system for use with oscilloscopes, spectrum analyzers, network analyzers, and other instruments. It presents a 1.1 pF or smaller load to the circuit being tested, and can be successfully used on high-frequency circuits, high-impedance circuits, tuned circuits and the like where conventional probes would upset circuit operation.
Most active probes cannot handle high voltages. This one operates up to 200 volts (DC plus peak AC), depending on frequency, and permits measurement of small AC signals in the presence of large superimposed DC voltages.
LC-2 Product Manual Version 1, June 2014.

SB-390 Product Detector / SSB Adapter

$105 US plus shipping
This adapter provides excellent SSB reception in R-390 and R-390A receivers. Like our other adapters, it uses a single-balanced product detector circuit with a broad dynamic range and a dual-time-constant AGC system. All controls operate as before, with minor exceptions. It mounts on the back of the receiver, and is powered from the receiver. AM operation is unaffected.
SB-390 Product Manual, Rev. 3, May 2013 for serial numbers 27 - 36.
SB-390 Product Manual, Rev. 4, July 2013 for serial numbers 37 and up.
SB-390 Product Manual, Rev. 5, December 2014 for same serial numbers as Rev. 4. (Changes to manual, not to design.)
SB-390 Product Manual, Rev. 5a, November 2015 for same serial numbers as Rev 4. Fixed Figure 5 (the schematic diagram) which was improperly cropped. The revision number in the document is still Rev 5, not 5a.

SB-51 Product Detector / SSB Adapter

$63 US plus shipping.
This is the current SSB adapter for the 51J-3, 51J-4, R-388, and R-388A receivers. The product detector circuit is identical to that in the PD-3. The AGC circuit now uses a separate AGC amplifier for SSB, which provides a better "hang" characteristic. A dual-time-constant circuit resists blocking when impulse noise is present. AM performance is unchanged.
SB-51 Product Manual, Rev. 5, July 2014 for same serial numbers as Rev. 4. (Changes to manual, not to design.)

SB-75 Product Detector / SSB Adapter

$61 US plus shipping
Incorporating circuits nearly identical to those in the SB-51, the SB-75 provides excellent SSB performance in the Collins 75A-2 and 75A-3 receivers. As with our other products, AM performance is unchanged. If an NBFM adapter is present in the receiver, its operation is unaffected.
SB-75 Product Manual Rev. 4, December 2011.

PD3 Product Detector / SSB Adapter

This is our original SSB Adapter for the Collins 51J and R-388 series receivers. It provides a high-level single-balanced product detector and a fast-attack slow-return AGC system for SSB. AM operation is unchanged. It was available until November, 2010, when it was replaced by the SB-51.
PD3 Product Manual, Rev. 8, February 2010.

For a brief explanation of SSB Adapters, see SSB Adapters Explained.


Please note that our products require some skill and knowledge to install and/or use. We recommend that you follow the link to the Owner's Manual for the product before ordering. The manuals are in pdf format, and about one megabyte.

We sell direct and through eBay. Price and shipping are the same either way. Payment through PayPal to radio@treetopcircuits.com is preferred; please contact us if you want to use another method.

We ship within three business days of payment, via Canada Post, which takes 4-10 business days (occasionally longer). Please contact us for shipping costs.