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Operation 21-3 has been completed, it turned out to be
a near disaster (recording wise), we were able to record most
of the operation. Every VLF mission is a learning
experience, when something goes wrong, you make a note of it and remember not
to do it again on the next mission. So, what could cause me to run
back and forth checking all connections, five minutes before
T-12?
Well, it was a combination of four things:
Unpreparedness
We got caught up in doing some VLF related experiments, and
forgot to make sure we had everything working properly in time to
fix any problem that would pop up before T-12.
The cold
It was colder then we expected, this has a way of slowing down the
thinking process, also it tends to affect unprotected electronic equipment
in a not so good way.
Receiver design
The receiver that was going to be used is a very
well designed unit, it is housed in a microwave down converter box,
it is hermetically sealed , it even works under water! I designed
it to withstand the damp conditions at the site (the recording
equipment stays dry in the pickup bed). Also there is a circuit
inside that passes shortwave frequencies from the antenna input to
the receiver output, this configuration allows the WWV receiver to
use the very same antenna as the VLF receiver
Unfortunately it
was designed in Oregon, during the summer. It has never been tested
in the cold!
A low battery
The battery was not new, it wasn't old
either, however, the battery was not tested beforehand at the
site. The most probable cause is the receiver being left on
during the trip to the site - or maybe at home -
who knows?
What happened at the site?
After checking in with the property owner, to announce our plans
for the weekend, I arrived at the observation site at about 6:40 pm
local time. I started to assemble the antenna, hooking up all the
connections, and get the pentium II computer going. Cliff arrived
soon after, at about 7:00. He set up his walking stick configuration
to do some VLF recording experiments with our new Team member and
long time friend Ron Hunt. Ron showed up at about 8:00 pm. About 15
minutes before T-12 I tested the computer to make sure is was
configured properly. I ran a test recording of the WWV receiver, it
recorded just fine. Afterward, I switched to monitor the output of
the VLF receiver - I got a VERY LOUD SQUEAL (7 minutes before
recording time)! My instinct told me to check for bad grounds, all
ground connections were good at the recording end. I dashed over to
the antenna mount to check the receiver connections, they were all
in good health (the receiver is placed close to the
antenna, 100 ft of RG-58 coaxial cable with BNC connectors on
each end connects the VLF receiver to the mixer unit).
I disconnected the antenna from the
receiver. No change - the squeal persisted. At three minutes before
T-12 we had a serious VLF receiver malfunction! (a
famous NASA astronaut quote comes to mind: Houston, We have a
problem!)
I remembered that I had made a few spare receivers for cliff in
the past. I ask him if he had brought the bucket of VLF stuff to the
site (it is a cardboard bucket that was originally used to store
vanilla flavoring, it holds cliff's VLF supplies). Luckily, his
answer was "yes". With an invigorated spirit, I went to prepare the
spare receiver (called the "ulti-receiver") for reception.
To my
dismay, I rediscovered that this receiver - one that I had designed
and constructed, was not built to operate with the VLF data
recording system that I had in place. The first problem was
connecting the Ulti-receiver to the coaxial cable. It has a RCA
phono jack for the recording output, the cable has a male BNC
connector, I had to rig up an adapter connection, luckily I brought
several adapters just in case. I hooked it up and turned it on.
The built-in speaker was crackling and popping; sounded like it
was working properly. I went back over to the pickup's tailgate
to check for recording levels, it was much lower then the original
receiver, so I cranked up the recording levels to the maximum on
both the mixer and recorder. I switched the controls on the
mixer unit to listen to the WWV station receiver, which is used to
stamp the data tape with time marks: it was
silent!
Subsequently, it dawned on me. The WWV
receiver uses the VLF antenna to receive the time signal via a special
circuit in the original receiver. The
Ulti-receiver does not have this unique circuit. I had to improvise; I
grabbed some spare alligator clip lead wires to make
a temporary WWV receiver antenna. It barely worked. I look
at the clock, 8:01 and 45 seconds, UH OH, we missed the
first minute plus some. My hand - almost autonomously - whipped itself over
to the record button on the tape deck. Quickly, I hit the
time stamp button on the mixer and barely put a time mark
on the tape at 4:02 UTC. I went to get the failed receiver and popped
it open to check it out. As a result of the cold temperatures, the
battery lost a lot of voltage. Measuring it with my digital meter, it
read 7.68 volts. The reading was fairly low, but not
so low that receiver would not amplify. Apparently, the receiver puts out
a horrendous square wave when it is powered with low
voltage and chilled to about 35 degrees, later on that
night I replaced the battery with a better one and it worked
fine. I missed the T-5 time mark because I was too distracted working on
the failed receiver.
A couple hours after the operation, the Ulti-receiver died
because of the low temperatures. We are going to buy new batteries
for the next mission tomorrow and saturday, we will be experimenting
with several things, in addition to record the INTMINS Operation, we
are going to test out recording with a laptop computer, we have good
results so far, from the last time using Cliff's walking stick, and
Ron's laptop computer, we are also going to find a way to run an ac
generator from the site to power the equipment with minimal ac hum
getting into the VLF receiver. Also recording with several different
tape recorders, to see if they are worthy to record VLF.
well that's all for now folks, from Team
19 Leader,
Larry Kramer
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