Cake Dec 23, 2017
CAKE Notes for Dec 23 2017
We were delighted to welcome John AI6LY and to say how pleased we were to
see Ward AE6TY back from his African travels, good also to have Tom KW6S
taking a break from his time in Fresno . Our well tried and trusted crew
were Kerry K3RRY, Glen KG0T, John N5HPB, Fred KJ6OOV, Peter K6UNO and Cap
John (K6LY) introduced himself and mentioned his main interest being HF.
John described his KW station and antenna systems, many of us are green
with envy. Boat-anchor radios are another interest shared with several of
us. John posed a challenging question of how to determine the
effectiveness of the reflector in his 2-ele beam. Several ideas were put
forward and clearly there is no easy answer. Other readers are invited to
make suggestions. Ron mentioned his interest in using WSPR for gaining
signal to noise data in comparing antennas, BTW shouldn’t it be (S+N)/N or
possibly (S+N+D)/N ?
John N5HPB always brings interesting items. On this occasion he brought a
bench-top jig for working on PCBs and more news about his work to recover
an AN25D signal genr from way back. Tom told us this was a very fine
instrument which says a great deal considering the accuracy we have become
used to. John also does a great job making what he needs including 3D
printing or using a diamond cutter to construct pads for resistors in a
Tom amazed us by describing his new 1296 MHz array with 24 DB gain. The
effort required to install it above all his other antennas is astounding.
Apparently this only became possible with the aid of our intrepid antenna
climber Bob K6XX. For one Ham to risk life and limb to help another is not
unusual but in this case it was to be marveled at. Tom’s antenna farm has
more “educated aluminum” per square ft than anyone and in addition he
mentioned that his attic was also full of antennas . How he intends to
cover the new LF bands is yet to be described.
Glen and Kerry continued their prior discussions on Arduino projects such
as the touch pad Glen has made. Kerry brought along a recent book on
Arduino projects. Regarding books, Tom handed out some very useful texts,
Ron snapped up the one on vertical antennas which is a subject near and
dear to his heart and fodder for future CAKE meetings.
Peter mentioned his deep interest in high performance audio and spoke of a
low level distortion analyzer made by RTX in Denmark. Peter is well aware
of the professional microphones made by David WA6NMF and was envious when
I recalled having the privilege of being invited to see David’s work in
progress . Ward mentioned that common zip-cord can be used as a balanced
transmission line. While being lossy at RF, versions may have values of
characteristic impedance (Zo) useful as short phasing lines and at
moderate power levels.
Back to basics – Using Standard International units show that Zo for
transmission line in Ohms is R+ j0 =sqrt ( inductance in Henrys divided by
capacitance in Farads)
Fred was asked abut his views of the recent eclipse and clearly this was a
momentous experience for him. For once Ron didn’t have much to say but
remarked that the term “common mode current” is frequently referred to in
amateur circles but not mentioned in classical texts including Krause,
Terman and Shelkunoff. Ron prefers term “longitudinal current”.
All in all a most enjoyable final session for the year. Thanks once more
for showing and telling.
BCNU Jan 13 Ron W6WO