From this awesome blog I found called Kevin's Security Scrapbook, I found a cool book that looks like a must read:
"Now Hear This!" by Winston Arrington - Available again!
Now Hear This! Electronic Eavesdropping Equipment Designs by Winston Arrington - Sheffield Electronics - 1997 (NOS)
(Click pictures to enlarge.)
Winston Arrington's electronic eavesdropping and countersurveillance design book is available again.
A portion of the review by Kevin (full post here):
Technically excellent, with some very unusual designs, it contains about 125 schematics; all may be built with a moderate level of experience. There is also a (now dated) countermeasures section which was contributed by me.
This book was never easy to purchase. The first printing had to be ordered directly from Winston, himself. This revised and expanded second edition was only sold briefly via the now shuttered Sheffield Electronics website. And, once in a looong while, a used dog-eared copy would show up on eBay to quickly sell in the $50.-$75. range. None have appeared there recently, however.
The picture of Winston's signature is from my copy of the book. Sadly, Winston is no longer with us to sign more of them.