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© November 2009 Ben Duncan Research - UK & Russ Andrews Accessories Ltd - page 5 / 11





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around 6.5dB (just below a halving), while the regular Zobel used for comparison manages a worthy 3dB or so. It is very important to realise that these are relative figures, and very probably quite worst case absolute results, with the RF/EMI source impedance being set at 75 ohms. In other words, with more typical RF/EMI noise source's source impedances, the attenuation might be say 9 and 12.5dB; or 20dB and 16.5dB. In each case, the Zappeerator’s extra 3.5dB reduction remains valuable, particularly considering threshold effect.This is the threshold level, above which AM content in RF, is detected, which may worsen the ill- effect, in one tiny step. Equally, the ill-effect of RF may vanish or fall greatly, with one small step the other way. As to the seemingly small achievement of 3.5dB, anyone who has engineered with multiple constraints knows that such improvements may be hard won.

Analysis in the AC domain, again using MicroCAP-9, indicates the Zapperator's extra efficiency in the high UHF and low microwave realms - Figure 3. Network analysis performed with HP 4396A and HP 8754 up to and above 1GHz, confirms useful suppression is achieved (in 'realspace' - actual production realisations), albeit less perfectly smooth in the leaded form. Not surprisingly, having the tails lightly twisted together helps.The attenuation at high RF, above 300MHz, then matches more closely what Figure 3 predicts.


Note 1- To protect intellectual propert , and patents pending, an area of response is subject to non- disclosure. As the unit's greatest value is at higher frequencies, the undisclosed area hardly diminishes the displayed benefits.

Note 2 - It is assumed the reader realises that all simulations are ideal, and that physical realisations will display ripples and variances.

© November 2009 Ben Duncan Research - UK & Russ Andrews Accessories Ltd

Russ Andrews Accessories Ltd, 2b Moreland Court, Westmorland Business Park, Shap Road, Kendal, Cumbria, LA9 6NS, UK. Call UK Local Rate 0845 345 1550 Mon-Fri 9am-5pm, from abroad +44 1539 797300 Email info@russandrews.com Website www.russandrews.com


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