CAKE Feb. 11, 2017

CAKE Mixture 2/11/ 17

The familiar faces belonged to Glen KG0T, Tom KW6S, Don K6GHA, John N5HPB Peter K6UNO, Eric KK6IZY, Kerry K3RRY and Ron W6WO

Glen brought a number of items used in development of software for ATMEL uprocessors. These had been replaced with later versions but were nevertheless were quite valuable. Kerry was keen to have them. Nice touch Glen and sorry that you had to leave early. Glen also brought a 12” rule which DigiKey has given away; they have a myriad of useful information on them

Tom showed a prototype LC notch filter to reduce interference from KSCO. The Q of the torroidal coil was found to be controlling the notch depth as is usually the case. Tom made a very neat job of winding the coil and commented on the difficulty of winding a large number of turns on small cores. A point often overlooked is that turns need not be neatly spaced and indeed there may not be enough circumference. Winding turns on top of others may look messy but they will do the job. For comparison the coils used in the QRP labs U3S design require 105 turns for 54uH for 2000 meters and 70 turns 24uH for 600m That’s about 6ft of very fine wire on a T50 core guys !

Tom mentioned an old (and controversial) antenna called a T2FD which looks like a folded dipole with the ends terminated in a power resistor. Ron has more info if needed.
Before the meeting Don K6GHA had mentioned the purchase of a Buckmaster multi-band Off-Center-Fed dipole which we discussed briefly. It is a derivative of the original Windom rather hyped as involving “ due to the magical mathematical relationship between amateur bands” Not so for 17 and 12 meters. We await his report on this magical invention!

Other topics touched on briefly were Powering RFID tags, and noise reduction in 3-terminal regulators. Peter is now our authority on that subject. The Cool Poly material (discussed in our previous session) came up again in the context of Heat Sinks. John has professional experience in this intereting topic and mentioned software called Flowtherm . Ron expects to have some samples in due course.

The mystery item, provided by Eric, was a tank for collecting moisture derived from a rotary dessicant de-humidifier. This is a cunning contraption indeed and serves to emphasize that we welcome discussion on a wide variety of technical subjects.

Those who can not attend CAKE sessions can also participate by submitting questions to me.
BCNU Feb 25th
73 Ron W6WO