ham radio fox hunt attenuator

Description

first of its kind variable attenautor vs multiple switches. 1-20 and 21-60 db. with a 3rd option of bypass/straight through. constructed of double sided copper board made in manhattan style construction. used for radio direction finding. when close to the hidden transmitter the signal overloads the directional ability of the antenna. KG7HZQ 73s

perfect linear attenuation. with zero noise or signal drift. completely passive tested on uhf,vhf and hf.

Components

2 × dpdt switch

2 × 4.7 ohm ceramic film resistor

2 × 470 ohm ceramic film resistor

2 × 0-1000 ohm ceramic film pot

2 × so-239 Connectors and Accessories / RF and Coaxial Connectors

Discussions

Morgan Bailey wrote 12/04/2014 at 14:45

Schematic?

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KM4EFP wrote 11/06/2014 at 18:09

Nice work. Check out my project I have made a raspi fox hunt transmitter to find using your attenuator. Check out circuit design spen for making schematics on an android phone. I do all my work from my phone.

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jcaplins wrote 10/18/2014 at 16:14

Thanks, This is a really easy project and will be quite useful for quick and dirty comparisons . I like the box that you made from circuit board but built mine in a little metal box from my junk stash.

John KK4JC

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bird brain wrote 10/17/2014 at 23:28

correct linear taper pots. each side is a seperate pi network. the 4.7 ohm on and the 470 ohm on the other switch. the whole point of this for me was to have a quick and simple sweep setting for attenuation. a guy could figure out calibrations and settings but for me a switch flick and good twist is enough for my needs. constant impedence probably not. i didnt follow "proper" pi network values i just bodged together some numbers until i got the results i wanted.

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jcaplins wrote 10/17/2014 at 21:02

I assume these are linear taper pots? Also what resistors go where - can't tell from the photos.
A schematic would be nice. Also you could put calibrated reduction knobs on it for a bit more precise settings. I take it this is not a constant impedance attenuator? Looks like a great project for fox hunting or finding interference.

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ham radio fox hunt attenuator

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