ANDY BOLIN'S CLASSIC ANTENNA PHASING ARTICLE
Welcome to phasing! To the best of our knowledge,
a radical yet virtually unexplored concept. By the time you've made it
to the end of this literature you should be convinced that phasing is
probably the greatest stunt to come along for TV and FM reception since
the invention of the outdoor antenna!
As you look at this mound of information, you are
probably asking yourself if you need to know this much about phasers to
use one. The answer is NO, but it sure helps to have as much of an
understanding of the subject as possible. Everyone should try to
develope skills in thinking through various signal situations. If you
can do that, you won't just be nulling signals-- you will find yourself
peeking weak signals instead of nulling strong ones...removing adjacent
channel splash...getting rid of ghosting on TV and even eliminating
noise from power lines. Non-technical people should be able to skip
over our technical text and still have a good enough understanding of
phasing to install and use their own system. However, we will be
inserting many of our own observations and comments along the way, so
we suggest you skip nothing!
Figure 1 shows the basic phaser system. Notice this is nothing more
than two antennas coupled through a two-way splitter/coupler (hooked in
reverse) to the receiver. You can use the Radio Shack part number
15-1141 splitter or anything similar for these phaser applications.
STATEMENT #1. No matter how simple or complex the design of a phaser system, the
point where the two incoming signals mix (the splitter) must always
have identical signal strength on its inputs to achieve a null.
Notice in Fig 1 to meet the demands of the above statement, we have inserted an
attenuator in line with one of our antennas. We suggest you use the
Radio Shack part number 15-578 attenuator for this and all phasing
applications. The type of antennas you use doesn't matter. If you want
to use one small and one large FM antenna, that's fine. If you want to
use one FM and one TV, that's fine, too. Since an attenuator will cut
down on signal levels when inserted on the antennas trunk line, we insert
it on the antenna with the amount of gain. This means the only signal
loss to the system is the loss of the two-way coupler.
For phasing to
work properly, antennas should be spaced horizontally more than one wavelength apart.
We are assuming you are using separate rotors. When the antennas rotated
in a direction where their elements are closest to one another, the spacing should
not be closer than 10 feet for FM, 17 feet for VHF TV channels 2-6 and 8 feet
for VHF TV channels 7-13. Anything less than one wavelength spacing
usually results in reduced signal levels, not nulls. Anything less than
one-half wavelength is useless.
Now, let's actually use the "phaser" of Fig 1. On FM, let's assume you
aim your main antenna to the side or away from a 50kw station at a
distance of 50 miles (90km). That is, aim it where you want to create a
null. Now you turn the rotor on the other (phase) antenna in all
directions. At the same time the rotor is turning, you turn the
attenuator up and down. This may or may not give you a null. Chances
are against it, but it's worth a try. If it fails, move the main
antenna 10 degrees amd try it again. It may or may not work, but odds
will always be against you. I dub this the "pot luck" circuit. You turn
a pot and hope for luck, and in six months hope you haven't worn your
rotor out.
The above paragraph is all it takes for basic
phasing. It also offers us the opportunity to explain why phasing works.

Figure 2 explains this in very simple terms.
Suppose for a moment you stand on the roof of your home and wave a
magic wand that lets you visibly see a signal from just one FM or TV
station. You could call the signal an AC voltage since it has a
positive and negative component to it. Since you now have the power of
visibly seeing the signal, suppose we place an antenna at a point where
the signal is at its most positive point...point A on Fig 2. Now
suppose we put another antenna at its most negative point...point B on
Fig 2. Now let's combine the two signals together with our antenna
coupler. Since we have combined our two antennas, the voltage output of
our coupler would be the same as if we laid figures 2A and 2B on top of
one another. That is, at any point in time if antenna 2A sees positive,
the 2B antenna sees the same thing negative. If you add these positive
and negative voltages together at any point in time, the output would
always be zero volts, and zero volts means (point C on Fig 2)...
no signal, a null! As you look at Figure 2, it should no be
apparent why statement #1 is imperative. If the signal at the coupler
from both antennas isn't identical, the voltages would add to something
other than zero.
Getting back to our "pot luck" system. In this case by our turning the
attenuator at the same time as rotating the phase antenna we are trying
to hit a point where the signals are the same in level (with the help
of the attenuator), while trying to find a spot that is out of phase
with the use of our rotating antenna. There is no statistical way
to calculate what percentage of time the "pot luck" system will work.
But in order for it to work at all in our example, the phase antenna
must at least have as much gain while aimed into the undesired station
as the main antenna has aimed where you are trying to create a null.
This means the more gain the phase antenna, the better the odds. All in
all, don't plan on anything better than a 1 in 20 chance. The
reason for the "pot luck" system working so poorly is the
fact that the only element to the system controlling phase is the phase
antenna itself. There is a much better way!
Those AC signals
we talked about in Fig 2 are also present in the coax. If we were to
cut a piece of coax off of one antenna (but not the other), it would be
the same thing as moving your finger from left to right over Figure 2A
or 2B by whatever distance. The point is a spot would be reachedwhere
2A and 2B are out of phase and we have a null by simply snipping off
pieces of coax. Instead of snipping coax, you could make up coax jumper
cables of various lengths to splice in line as needed. But splicing in
various cable lengths is still putting us in one fixed phase. We need
something tunable; we need a phase box.
IMPORTANT COMMENTARY. When it comes to an actual phase box,
a key question is how much control of the phase spectrum does the box
have? Perfection is to go from in phase to out of phase to back in
phase (360 degrees). When we began our research, we found out real
quick that almost any circuit you cared to dream up would have some
control over the phase spectrum, but it was very limited. Things that
worked on paper won't work in reality. Once you've gone somewhere
around +/- 30degrees, if the impedance mismatch doesn't get you, the
loading effects will. Subsequently, we gave up on the idea of a single
stage (tuned or untuned...ganged or unganged) circuit getting control
over the entire 360 degree spectrum. To the best of our knowledge, it can't be
done...but it CAN be done with a two stage tuned ciucuit.
While we were in the process of researching our phase box, a
commercially available model showed up for sale in a CATV trade
magazine. The manufacturer is charging over $500 for the unit. Since
the unit only has one control on it for phase, we assume it doesn't
have more than +/- 30 degrees of control. A few months ago another
company introduced their phase box in a trade magazine. They even tell
you if you cannot get a null to splice in different lengths of coax to
get their box to work.Since we are
dealing with a new concept, there is no printed literature on this
subject anywhere. It is alot of research time and a lot of research
money spent. These people are in business, and we don't condemn them at
all for charging over $500. What we are trying to do is say "buyer
beware". If you decide to purchase a phase box from someone be sure to
ask these two questions. First, how much control over the phase
spectrum does the box have? Second, since it is being sold mainly to
CATV companies, it may be a "set and forget" model; meaning you use it
a few hundred times and it wears out because it was made using sleazy
tuning coils that weren't meant to be fooled with all the time.
What we have done is on a hobbyist basis. So we can afford to build and sell
our 360 degree phaser for a hobbyist price. But, since we have a lot of
research money to recuperate, we do not sell or give schematics for our
box. Besides, you are dealing with tuned circuits that are tough to
build and you wouldn't have a working model to compare against it
anyway. This is as good a time as any to say, since sales are slow,
that there are three areas we did not get researched. We have not tried
a UHF model. We have not tried to build a channel 2-6 and 7-13 phaser
in a common box. Various horizontal distances between antennas as well
as staggered antennas.

Figure 3 shows a 30 degree phaser. In reality, I am sure
it has more than 30 degrees of control, but the results may be poor
past that point. For that reason, we dub this circuit our "1/6 of a
phase box" since that is what it is! But, this little circuit is a real
work horse. It's cheap, simple to build, has a built in attenuator and
a few other things, too! So we will be nice and not call it a "1/6th
phaser". We will instead call it a "phase tilter".
When it comes to a real phaser, the phase antenna system you use is important.
For the 30 degree unit, we suggest the same antenna setup as for the phaser
we sell, so simply read the information.
IMPORTANT NOTE:
From this point on, we will call the process of statement #1 "balancing
the line". How you accomplish it is up to you. If we are talking about
an FM receiver with one antenna unplugged, if you get a signal meter
reading of S3, and then you switch antennas, then that antenna must also read close to an
S3 or there will be NO null. (Note: when the main antenna is unplugged, rotate phasing knob or knobs
for maximum S meter reading). In the case of TV, simply match the
graininess or snow in the video. Think this through! If the phase antenna is real low in gain
compared to the main antenna, the only way to get a null is to aim the
phase antenna at the station causing the interference and the main
antenna to the side or back of the interfering station and hope that
the phase antenna has enough gain to get an S3. If it does not, the
only thing you could do is add an ateenuator to the main antenna. But,
now suppose you use the same make and model of phase antenna at the
same vertical height as the main antenna. You would never have to aim
the phase antenna in one direction and the main antenna in another,
just aim them both on the same heading. It doesn't require you to
"think" how to aim the phase antenna. Also, with the phase and main
antenna having the same gain, you can aim directly into semi-locals and
vaporize them! We will discuss system performance and antenna
directivity later, but for now understand how important phase atenna
gain is.
On TV, you are looking at the snow level to balance the line. In this case, you can get
away with using different makes and models of mast mounted amplifiers.
You can even get away with an amplifier on one antenna and not the
other. But on FM you are looking at an S meter. So of course if you put
a noisy amplifier on one antenna and not the other, you can't balance
the line. On FM use no mast mounted amplifiers or use the exact same
make and model on both antennas.
For those who read schematics, notice our phase tilter of Fig. 3 is not a tuned circuit.
All phasing is actually being done by the capacitor. Therefore, this
circuit has an advantage over a tuned circuit. That is, it has a very
broad bandwidth. Without any modifications this circuit works from 54
to 216 mhz, which is all of VHF-TV and FM. A tuned circuit is limited
to +/- 30 mhz, but it can do a 360 degree phase shift. So it's a nice
trade-off. Fig 3 will give a nice phase tilt across the wide range of
frequencies, but it requires the user to try as many as six different
lengths of coax to get a null.
Construction of Fig 3 is straight forward and hassle free. The
capacitor should be an air variable plate type; that is, at least a
"medium" in physical size and is the isolated from ground type. If
possible, install the capacitor in the chassis first and check the
capacitance to ground with a digital capacitor checker. If
capacitance is higher than 6pf, the tilter will not function properly.
Meaning your capacitor needs better isolation from ground.
Notice Fig 3 has a built in attenuator on the
phase antenna. This setup is assuming the phase antenna has poor gain
compared to the main antenna and that the phase antenna will always be
aimed at the station causing the interference while the main antenna is
aimed somewhere else. But if the phase antenna is high gain and you
always want to aim it in the same direction as the main antenna, leave
the bilt in atttenuator set for minimum resistance and put the 15-578
attenuator on the main antenna's line. As we have already pointed out,
on a phase tilter
if you cannot get a null, splice a coax jumper in one of the antenna
trunk lines. On VHF-TV, since we are talking about a wide range of
frequencies the length of coax is pretty unpredictable. You would need
one length for channel 2 and another for channel 13. All you can do is
try a foot or so at a time, and hope you score a hit. FM, only being
20mhz wide is simple to calculate. From whatever phase point your
tilter happens to be at once installed, you can move the nulls as
follows. To move your null 30 degrees, add a 6.5 inch jumper. For 60
degrees, add a 11 inch jumper. For 90 degrees, add a 19.5 inch jumper.
For 120 degrees, add a 26.5 inch jumper. For 150 degrees add a 32.5
inch jumper and for 180 degrees add a 39 inch jumper. These lengths are
calculated solely for 75 ohm coax with a velocity of propagation 66%.
Of course if you use coax with any other specs you will have to
recalculate the above lengths. Basically, these specs are for most
Beldon RG/59 and 11 coax. Nothing from Radio Shack has these specs.
Please consult your coax catalogs before making any jumpers. Good Luck!
THE 360 DEGREE PHASER
This is it - the 360 degree phaser! Imagine being
able to aim into a semi-local and null it. Turn yur antennas ten
degrees and null it again. Turn your antennas another ten degrees and
null it again. And do it again and again and again all the way around
the entire 360 degree phase spectrum! That's a 360 degree phaser, null
anter null without the messing with coax jumpers! Once you've learned
these few nulling techniques you'll be nulling stations in less than
ten seconds!

Fig 4 assumes the phase antenna is high gain. If
it's not, you won't be able to balance the line on the same antenna
heading as the main antenna, so move the attenuator to the phase
antenna. Then, always aim the phase antenna at the station causing the
trouble and the main where you want the null. This is giving up the
ability to aim both antennas in identical directions, but with a very
low gain antenna there is no other alternative.
Here are step-by-step instructions for balancing
the line with your 360 degree phaser as shown in Fig 4. (1) disconnect
the main antenna. (2) rotate the knobs on the phaser for maximum S
meter readings, or by viewing the TV signal strength. Note the reading.
(3) reconnect the main antenna and disconnect the phase antenna. Adjust
the attenuator for the same reading or level as was obtained at the end
of step (2). (5) reconnect the phase antenna and begin lowering the
signal levels by going back and forth with the two knobs on the phase
box. That's it. We will describe a "quick null" method in a moment. But
keep in mind that the "balance the line" method is the most reliable.
The above will always work assuming the antennas
involved are close in gain. But on FM a high gain antenna shows more of
a noise figure than a low gain antenna on the S meter. So if you are
using a high and low gain antenna, once you've balancd the line you may
need to add a small amount of attenuation to the main antenna to get
the null.
You must use the "balance the line" approach when
strong signals are involved. Our definition of a strong signal in this
case would be aimed into 20kw at 50 miles (80km) for FM assuming a high
gain system. Since your S meter will be slammed, one way to accomplish
the null task is to sneek up on it. In other words, with the strong
signal detuned, use the "balance the line" method. then, tune a little
closer and keep trying to lower the signal for the null. If you are
technically inclined, the best way to deal with this is to modify your
S meter ciurcuit with a control for turning down those strong readings
on locals. Then you can use the "balance the line" method with just one
pass at any signal level no matter how strong it is.
Here is a way to deal with strong TV signals and
another way to handle strong FM signals if you don't want to modify
your S meter circuit. Add a 15-578 attenuator to th phase antenna. You
now have an attenuator on goth antennas. On TV, using the "balance the
line" method, turn up the attenuator on one antenna until you just see
a grainy picture. Switch antennas and adjust the other attenuator for a
grainy picture(the same signal level). Adjust the controls on your
phase box for the null. Now you can turn the controls up on the two
attenuators by an equal amount (until one attenuator is at maximum level)
and you will go back into the null.
What we are doing here is over attenuating both antennas so we can get an S
meter reading, or see a grainy picture. Adjusting phaser, then turning
both attenuators back up by the same amount puts us back into null
without touching the phase box.
By now you should have a good understanding of phasers and how they work. An attenuator
adjusts signal strength. A phaser adjusts phase. By making the signal
levels identical with the attenuator, then adjusting the phase box, you
should be able to obtain the desired peaked or nulled results and that
is what this is all about!
When using the 360 degree phaser and signals weaker than described above, there is a
shortcut that gets you out of balancing the line. We call this the "Quick Null" method.
This is assuming both the main and phase
antennas are aimed in the same direction and the phase antenna system
has within 10db as much signal as the main antenna system. With your
15-578 set for minimum attenuation its knob pointer points at the 5
o'clock position. Just try the two controls on the phase box to see if
you get a null. If not, turn the attenuator knob to point to the 3
o'clock position and try the knobs on the phase box again. If not, try
the attenuator in the 1 o'clock position and try the knobs on the phase
box again. Using this system with just a little practice you will be
abl to "nuke" stuff in less than 10 seconds! The only
thing missing from Fig 4 is a way to switch between antennas for
balancing the line on those strong signal nulls. Of course you could
unscrew the coax at the coupler. There are two better ways. You can use
push-on quick connectors such as Radio Shack part number 278-218, or
use a high isolation A/B switch. Never use the push button type antenna
switch because of poor isolation. The sideway movement sype slider
switch is usually best. Just come up with something rated as good as
50db isolation. There are also some sneaky methods as well. Such as
turning off the AC on the mast mounted amplifiers. You could even mount
some antenna switching relays in your system...just think it through.
If you will be using two phase boxes, one box for channels 2-6 and another for 7-13,
space them with a 3 foot jumper connecting them in series. There will
be some minor interaction between controls on the two different boxes. As a rule, both
models of TV phasers will work for FM, but the attenuator will have to
be set substantially higher, like on the order of 10db. The FM model
will only work on channel 6. This is not written in stone since the
phasers are hand built.
Is your phaser working properly? Installation of
the 360 degree phaser is as pictured in Fig 4 except for whatever you
decide to use s an antenna switcher for balancing the line. Once
everything is installed, we suggest you try a few different cable
lengths spliced only into the phase antenna side of the line to see if
you can get the phaser to perform any better. There are three warning
signs to alert you that a coax jumper needs to be added: (1) You can assume soething is wrong if a
station will null while a different station in the same town with the
same power will not null. (2) The pointers on the knobs on your phase
box usually point down when you reach null. This is an indication that
the coax is almost out of range. (3) The left control on the phase box
does not seem to do much, or performs sluggishly, when it should have
the same sharp peaks as the right control has.In all cases try adding, or removing, 17
inches of coax from the phase antenna side for channels 2-6 and FM, 10
inches for channels 7-13. Ideally the knobs should point near up on the majority of your nulls and both
controls should have sharp peaking. If you are still not getting
correct or enough nulls try coax jumpers of various lengths. This is
not a critical situation and once completed you will not have to mess
with jumpers again.
Again assuming near identical antenna systems. You can use your 360 degree phaser for
more than just nulling stations. You can aim both antennas at a weak
signal that is not being interfered with and peak the signal with the
two controls on the phase box. This usually helps lift weak stations up
to usable levels. Also the peaking technique can be used for those
nasty violent fading signals. Your 360 degree phaser will usually
stabilize fading signals by at least 50%. If you have power line noise
we suggest using the quick null method described above for eliminating
that problem.
We hope it is clear how important phase antenna system gain is. It is having near
(within say 12db) the same gain as the main antenna is the most
important feature of the system you install. But I feel another
statement coming on.
STATEMENT #2.
Once you have made it into a null, the best directivity you
will have will be the worst directivity of the two
antennas!
An example for statement 2. Let us suppose (from central Illinois) I want
to listen to Columbus, Ohio on 97.1 with Indianapolis on the same
frequency in the same direction. If both antennas are high gain FM
antennas I should be able to do it. But what if the phase antenna is a
less directional VHF Tv antenna, even if it has as much gain as the FM
antenna? The answer is, even though both antennas are aimed into
Indianapolis, the most likely thing I will hear is St. Louis,
MO off the back of the system. It is not difficult to
understand why the system works the way it does. Look what would happen
if Indianapolis went off the air. If both antennas were aimed east, and
just the FM antenna is hooked up it would receive Columbus. But when
just the less directional TV antenna is hooked up, it would receive St.
Louis off the back of the antenna. So, a phaser can make a station look
as if it is not on the air, but when in a null the directivity you have
will be the worst directivity of the two antennas involved.<
The above is to prove a point. The more directional
the two antennas are, the better off you are. But still a VHF and an FM
antenna work very well together on FM. In fact, it works well enough
that I would not spend the money of a second FM antenna if I had a good
TV antenna already installed. Of course, the TV antenna will have to
have good gain across the entire FM band.
Let's take statement 2 to the ultimate extreme. If
you used a five element FM antenna at 20 feet, and for phasing put a
non-directional single element S antenna at 60 feet, then once in a
null that null would be non-directional. Whatever the next strongest
signal was, in any direction, is the one you would receive.
Anticipating Results. This brings us to the next
part of our discussion. Results vary dramatically for TV and FM. Also,
horizontal spacing is a contributing factor. On FM, you should be able
to aim into 10kw at 50 miles and not be able to tell it is on the air.
For 20-50kw stations at 50 miles it really depends on how well the
station gets out. As a rule, you can get a null on a 50kw at 50 mile
station if another signal is behind the semi, but it will probably not
stay tuned. It may drift. Don't let anything stop you from trying! Even
if you cannot get a null aimed into at 50kw does not mean you cannot
get a hull on that 50kw station at 15 miles when aimed to the side or
back of it. When they are this strong, you may make or you may not.
TV is another story since you are dealing with
separate audio andvideo frequencies. You already know the nulls you get
by just using one antenna usually do not result in "nuked" signals. You
dump the audio or video but generally not both at the same time. A
phaser will usually work in the same manner. You will dump one or you
will dump the other, but don't plan on both at the same time. As a
rule, using the 360 degree phaser will get you an audio/video null
together perhaps 1 in 3 times. The stronger the signal, the less
likely, while the weaker signals (over 80mi/130km) does not have a bad
chance of a complete audio/video null. In most cases you can have a
choice of whether you tune in the video or the audio. Otherwide the
story is the same as FM. If you aim into a 50 miler you should be able
to dump the audio or video for the next TV station up the road.
A channel 2-13 antenna works fine for TV, but
statement 2 applies, so you are much better off running a channel 2-6
phaser to a pair of channel 2-6 cut antennas. The same goes for
channels 7-13. There is one thing you want to be sure not to do.
Whatever you do, do not put up a pair of channel 2-13 antennas in which one
antenna has substantially better gain at channels 2-6 while the other
has better gain at channels 7-13!
STATEMENT #3.
It is always worth keeping in mind that you cannot achieve a null if you allow the phase antenna to
have more gain than the main antenna.That is why we designate the phase antenna
as the antenna with the least, or equal, gain.<
Looking at Fig 4, it would be assumed that if both antennas were identical,
spaced approximately one wavelength part and one common rotor,
that the signal strength would always be the same on both antennas no
matter what. This would theoretically mean no more attenuators! Well,
it does not work because of antenna interaction. In fact, there is a
pattern to the interaction. If your system is aimed north, south, east
or west, the pattern makes the shape of the letter X, meaning that you
do not have to use the attenuator unless you are in one of the points
of the letter X. Then you may have to crank the attenuator up to 2 db
or so. The point is that you cannot get out of using the attenuator
even with common rotor horizonta stacking. The only disadvantage to
common rotor stacking is the wind and ice loading. Of course, as with
regular horizontal stacking, the horizontal mast must be made of a
non-metallic material. For now we assume you will get good results with
any spacing in which the elements from the two antenna involved do not
come closer than a wavelength to each other: 10 feet for FM, 17 feet
for TV.
Whether you use
common rotor stacking or an antenna at 50 feet on one side of your home
and another antenna at 25 feet on the other side of your home, you can
expect astonishing results with your 350 degree phaser!
Finally, an answer to the most common question we get. Can a phaser be used to stop overload?
The answer is yes assuming the overload is
in the receiver and not the mast mounted amplifier. But it does not
make sense to use a phaser because it stops you from using your rotor.
Once you have turned your rotor 2 degrees you are out of your null.
Even finding the null on something so close that is is causing overload
takes a considerable length of time. In reality you do not get a null
on something this strong. The signal turns distorted. It strips the
carrier and leaves you the sidebands. The way to handle overload is
with asingle frequency trap. On TV use a 15db trap with a 2mhz
bandwidth. On FM a 15db trap with a 500khz bandwidth works fine. The
nice thing about traps is they can be made with negligible insertion
loss so you can string them together in series.
In summary, we have gone through a lot of text to simply say have identical signals
from any two horizontal antennas spaced fore than a wavelength apart,
run them through a phase box and you will probably get a null. That is
the bottom line. Just because we went through all kinds of variables in
our text should not be a reason for you to be confused.
Even if you choose not to purchase a 360 degree phaser, we sincerely hope you will do the
next best thing and try our phase tilter (Fig 3).
Andy Bolin
Charleston, Illinois USA September 1991
PHASER UPDATE...OCTOBER 1993.
Regarding Phaser - page 3 first paragraph. Is your phaser working
properly? In many phaser installations the cable length is far more
critical than we originally realized. Some do-it-yourselfers report
just a few inches of coax placed anwhere before the coupler can be the
difference between reduced signal levels versus very deep nulls. On the
other hand, many installers find all but a few lengths work properly.
Of course, changing cable length before the coupler (even if just an
inch) changes the time it takes for the signal to reach/mix in the
coupler and thereby has a major effect on the phase of the system. The
reason this is so pronounced on some phaser installations and not
others is assumed to be antenna spacing. We want to advise you to be
prepared to experiment with as many different cable lengths as needed
for installation. On FM you should be able to aim your antennas
directly into 6 to 10kw stations at 50 miles and not be able to tell
that the station is on the air, 80 miles for TV. Once the right length
is found you should have deep nulls on all such powered stations
withoug again playing with coax jumpers. If you are not getting these
kinds of nulls, something is wrong! And that something is probably your
cable length. As mentioned in your text, you cannot get these deep
nulls with antenna spacing of less than one wavelength.
For more information on phase box availability and pricing, contact the
author, Andy Bolin, Charleston, IL. at dxshack at gmail dot com. The email address
is good as of late 2019 and since the boxes are individually made as ordered,
they may still be available.
Printed with permission of Andy Bolin
This page revised Sept 4 2020