The HP 335 modulation monitor provided the visual and aural carrier
frequency monitoring. I don't think I visited a transmitter that
didn't have one for many, many years. Even if they had a later unit,
most places kept the HP also.
Actually we did have the Marconi sideband analyzer that was provided
by the State after the colorization. I know Jeff felt he never did
quite master the unit, though it apparently had some advantages over a
general purpose spectrum analyzer and a sweep generator. It was at the
bottom of the left hand rack that we added for the color conversion.
The scope used to monitor the visual modulation was the Tektronix 529.
The important thing was learning to use the zero carrier pulse to
generate a reference point and then remember that we actually looked
at the modulation upside down: the higher the waveform got the less
the modulation.
We had one color monitor, a Ball-Miratel 12 inch unit, to see how we
looked in color.
The Tektronix 144 and 147 test generators the State provided made us
the envy of a lot of stations that were still using first and second
generation test generators. Even when I got to WBNS, they were still
using a Riker solid state test generator at the transmitter and a tube
type test generator down in master. There was a Tek 144 making bars
into the router.
When we got the direct PBS microwave feed the color certainly started
looking better. The color programming that we got off air from WOSU
was somewhat impaired.
The other piece of modern test gear we had was a Tek 453 oscilloscope
that we used in place of the 524 and even took on remotes and
minimotes when necessary. The odd thing about that scope was that one
channel occasionally acted up. If you banged on it, it would be fine
for a while. I accidentally found the problem a year or so after we
got the scope. One end of the resistor connecting the input connector
to the circuit board had never been soldered at the factory.
The Hickok tube tester with the built in roll chart listing the tubes
was actually a lot of fun for the first 20-25 tubes. After that it got
tedious.
You mentioned the GE engineer, Sabeff, who disliked the modulator so
much. Do you remember his comment one evening when he got disgusted
with the progress he was making? And do you remember asking WCLT to
shut down their transmitter long enough to confirm that the birdie he
was chasing wasn't an external signal?
He was amazed when he walked in and saw the iconoscope still
operating. Do you remember where he'd last seen one working?
You didn't mention the pretty blue glow of the mercury rectifier
tubes. Imagine the EPA permits you'd need today to run those tubes.

Daniel

--- In WGSF_TV@yahoogroups.com, Leland & Dorothy Hubbell
<lhhubbell@...> wrote:
>
> I will send this in two parts - it is long.
> Additional comments and corrections are welcome.
> What are your memories of the transmitter?
> Those of you who moved out into the greater universe of radio and/or
> television broadcasting -
> please lend your thoughts as you encountered the world away from our
> cozy little 'planet' on Horn's Hill.
>
> I am still hoping to get input from everyone who had a part in the
> history of the station.
>
> The WGSF transmitter - Part 2
>
> The transmitter operator or engineer maintained a record, or log, of
the
> various operating parameters, according to FCC rules and regulations.
> All of those meters told the operator something about how the
> transmitter was performing, for better or for worse. The settings that
> kept the transmissions at the proper channel frequencies and output
> power were captiously observed, accordingly noted on the log, and
> adjustments were made if needed.
> Initially, the station had one oscilloscope to display the video
signal,
> a Tektronix model 524 AD on a Scopemobile. It doubled as test
> equipment for any video signal work. Eventually, a dedicated
> oscilloscope monitor for the transmitter was obtained. Colorization
also
> provided a video signal generator, which helped tremendously, but still
> did not provide the essential services of a sweep generator for
aligning
> the visual channel, or chain.
> Another required monitor displayed the operating frequency of the aural
> and visual transmitters. Those readings were also logged by the
> operator, noting any deviation above or below the assigned channel.
That
> monitor was itself subject to changes over time, and both the
> transmitter and the monitor had to be adjusted periodically to stay
> within legal specifications. The station subscribed to a monitoring
> service called Woodward Labs in Mt. Vernon. The monthly report was
> noted in the transmitting log, and kept on file. Adjustments were made
> if needed - and they usually were.
> All of the original equipment at the station used vacuum tubes -
lots of
> vacuum tubes. Vacuum tubes wear out: their performance drops over time,
> or they even short out entirely. Most of the test equipment owned by
the
> station when it initially went on the air was from a radio/TV repair
> shop that was bought out. The device used to test vacuum tubes was
> essentially for home type electronics, but covered most of the common
> tubes used in the WGSF equipment, but still mostly go/no go readings.
> The purchase of a more industrial oriented model made the task of
> preventative maintenance both easier and more accurate. Every tube was
> checked on a periodic basis, and the readings kept in a database.
> Most tubes used at the station could be purchased locally from an
> electronics supply store, the same place the radio and TV repair shops
> bought theirs. The major transmitting tubes had to be obtained from a
> dealer of industrial tubes in Columbus. The power amplifiers, or
> finals, were made only by General Electric, and cost over a thousand
> dollars. We babied those beasties, and kept a special card under a
> serial number on file for each one.
> We followed a special turn-on routine for the transmitter, starting at
> reduced power, and gradually increasing to the normal operating power.
> The transmitter also had special circuitry designed to ease the tube up
> to normal parameters, so as not to damage the heater or filament in
> the tube. Still, most tubes didnt just wear out; they would die of an
> open filament, burning out like a light bulb, their distant cousins.
> They could also sustain an internal short between elements, no matter
> how carefully we watched over them.
>
> Still, some of the specialized transmitting tubes could not be checked,
> except by the operating readings monitored and indicated by the meters
> on the transmitter itself. Thus the chore of taking and recording an
> hourly set of readings had a practical aspect besides meeting FCC rules
> and regulations. The maintenance technicians could note the performance
> of those tubes, and replace them when necessary.
> Changing any tube in the radio frequency chain that generated the
> broadcast signal necessitated retuning the amplifier stage, simple in
> the case of the aural channel, but an often laborious process in the
> visual channel.
> Broadcast signals must conform to very stringent standards. Meeting
> those standards was always a challenge at WGSF. The aural transmitter
> was fairly straightforward, and generally required only a minimum of
> attention. The visual section was literally a nightmare!
> The visual transmitter required a tuning process called broadbanding.
> That meant that more than a dozen adjustment points had an impact on
the
> proper overall performance. Further, WGSF never had the proper test
> equipment, a sweep generator that would trace a picture of the
> bandpass on an oscilloscope screen. We could only stand, look over
their
> shoulders, and drool at the test equipment technicians brought in on
the
> two occasions that we had modifications supplied, once by Nationwide at
> the channel change from 28 to 31, and when the state network paid for
> the colorization.
> Picture a partially filled tube of tooth paste: Squeeze it here, you
get
> a dip. Squeeze another place, that dip changes, but you get another
dip.
> Pretty soon you no longer have the nice, smooth tube that you started
> with. Now multiply that to the square of 12 - or more. Thats what it
> was like to tune the visual transmitter. Pretty much by guess and by
> golly!
> Add to that the device that put the picture information on the radio
> frequency carrier. The modulator was maddening. It never worked as
> desired, ever. It nearly drove GEs own engineer to total despair
during
> the conversion from channel 28 to channel 31. He would get on the
> telephone to the guys in the engineering department back at GE,
mumbling
> things uncomplimentary about the modulator.
> He came to hate a particular, though essential, piece of test
equipment.
> It would simulate a picture change from total white to total black. The
> meters on the transmitter would flip wildly, the protective circuitry
> would kick in with a klunk, and kick the whole box off the air. Over
> and over! Yes, he despised both the modulator and the standards that it
> would not - could not - attain.
> There were certain vacuum tubes in the modulator that could be pulled
> from their supposedly normal locations and placed in sockets labeled
> Emergency Operation.  Every transmission at WGSF was an Emergency
> Operation.
> The transmitter was turned off for the last time on June 30, 1976. The
> transmission line, the 3 1/2 inch copper pipe leading up to the
antenna,
> was switched over to the new translator that was installed and operated
> by the Ohio ETV Network Commission.
> The new box operated on the same channel as WGSF, Channel 31, and at
the
> same power. The station, however, was quiet, except for the hum of the
> new unit as it automatically turned on when WOSU-TV, Channel 34 in
> Columbus, began their broadcast day on July 1. The Federal
> Communications Commission was accordingly notified, the license to
> broadcast was canceled. The WGSF transmitter sat dark and cold,
never to
> be turned on again.
> The school district, owner of the station, had one query with intent to
> purchase the transmitter, but no further response occurred once the
> technical information was sent to them.
> The city and county used the WGSF tower for their two-way radio
antennas,
> and the equipment was housed in a room in the south east corner of the
> building. They requested permission to utilize the now unneeded space,
> stripped of all but the old transmitter, to install additional
equipment
> for their communication services. Permission was granted to the local
> amateur radio club, who had moved their amateur repeater equipment into
> the former WGSF audio production room, to dismantle the transmitter.
> None of the former WGSF staff was there to witness that final phase of
> the history of WGSF.
>