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Australian Made Broadcast Equipment

Somebody working to preserve a record of past work:

Some of these have familiar looking cabinets and tube arrangements. They all look like classics to me and it is good that they are being saved. I noticed at the end of the video there is a Harris MW10A. As for the RCA Ampliphase transmitters; I maintained a BTA5J in Harrisburg PA on 580 KHz. It was reliable enough, but I could never keep it sounding good for more than a couple of days.

In any case, a worthwhile effort.  More information at: AWA Transmitters.

Details

I found this small, yet very important detail on a DB-37 connector attached to the back of a Nautel V-1 transmitter:

DB-37 connector for Nautel V-1 transmitter

DB-37 connector for Nautel V-1 transmitter

The black wire is the ground wire and the orange wire is the remote RF off command.  A closer view:

DB 37 connector from Nautel V-1 transmitter

DB 37 connector from Nautel V-1 transmitter

The transmitter had been shutting down unexpectedly since it was installed.  When these shutdowns occurred, there was no overload, no fault, no power interruption or other indication of a problem.  When the RF on command was issued, the transmitter would turn back on and run with normal readings until it shut down again.  It was a bit of a mystery; the transmitter was removed from its mountain top home and hauled back to the shop to be repaired.  It was connected to all sorts of test equipment and studied intently for many days.  Still, the problem could not be replicated in the shop.

Then the transmitter was hauled back to its mountain top transmitter site and re-installed.  It ran well for about a month and then started going off again.  This time somebody looked at the event log and noticed that a “Remote RF off command” was being issued at the same time the transmitter would shut down.  Ahhh, the missing bit of critical data.  That prompted me to take apart the DB-37 connector used for the remote control interface.  The problem was obvious as soon as I removed the hood.

Sometimes the most valuable piece of test gear is the venerable Mk I, Mod 0, EYEBALL.

I unsoldered the ground lead and put some heat shrink over the connection to the DB-37.  Hopefully, that will take care of it.

Water and transmitters do not mix

This incident happened a few years ago.  I thought I had lost the pictures of the disaster, but I found them this morning on my thumb drive. Hooray!  This occurred one morning just before Christmas after the area received a snow/ice/rain storm.  The gutters on the old ATT long lines building clogged with ice and the water on the roof built up.  Unfortunately, the transmitter was installed directly below a disused exhaust stack for the former backup generators.

I received the off air call from the morning show while I was driving to the office.  I diverted and went to the transmitter site and found water pouring into the top of the main transmitter.

WBPM transmitter room flood

WBPM transmitter room flood

Thus, water ran down directly into the top of the QEI FMQ-3500 transmitter (transmitter was upgraded to 6 KW). Unfortunately, high voltage and dirty stack water do not mix. The combination of sooty, iron laden water and the B+ damaged much of the transmitter circuits beyond repair.  The main transmitter is on the right, the backup transmitter is on the left.

I inspected the backup transmitter, also a QEI FMQ-3500, and it seemed to me that no water made it into the unit.  I rigged the tarp to ensure that none did, which was a very pleasing bit of work, what with the cold, smelly, dirty diesel water dripping on my head and running down my neck and back.

Top of WBPM QEI FMQ-3500 transmitter

Top of WBPM QEI FMQ-3500 transmitter

The 1 5/8 coax switch was also damaged:

WBPM 1 5/8 coax switch

WBPM 1 5/8 coax switch

As was the remote control in the equipment rack:

WBPM Gentner remote control

WBPM Gentner remote control

Fortunately, the backup transmitter ran, although I pressed the plate on button with a dry wooden stick while standing on a dry, non-conducting ladder.   Even so, I still felt a little trepidation holding that stick.

WBPM Saugerties, NY Nautel V-7.5 transmitter

WBPM Saugerties, NY Nautel V-7.5 transmitter

It took almost a year, but finally the insurance company for the building owner came through, and a new Nautel V-7.5 transmitter was installed.  I believe this is the last V transmitter Nautel made.  We moved the transmitter location across the room, not under the old generator stacks.  We also removed the generator stacks and patched up the roof with hydraulic cement and roofing tar.  By the way, that yellow color should look familiar to anyone who ever worked inside of a Bell Telephone System building.

 

FM transmitter site tour, Bavaria, Germany

Short, but interesting video tour of an FM transmitter site in Germany. The analog transmitters are 10 KW Telefunken solid state units, 5 main transmitters and two reserve units into an antenna combiner. At approximately the 35 second mark, the video shows a Rhode & Schartz DAB transmitter. Germany uses DAB+ in band III (174-240 MHz).

It is always interesting to see how others are broadcasting.

Harris exits the broadcast industry

When they sold their Broadcast Equipment supply division to SCMS a few years ago, the handwriting was on the wall. Even so, it is a little surprising that they would exit broadcasting altogether.

The decision to divest in no way reflects the quality of the work Broadcast Communications performed in support of our customers and our company.  Harris simply determined that Broadcast Communications could provide higher value and operate more effectively under a different ownership model.

They are spinning the broadcast division off to a new owner rather than completely shutting down the operation.  In an e-mail received from Harris Morris, President, Broadcast Communications Division, clients and customers will still receive support for existing products:

In the interim, Broadcast Communications will continue to be a part of Harris Corporation and operate business as usual. Our valued relationships, both longstanding and new, remain our top priority. The global Broadcast Communications team will continue to work diligently to ensure our commitment to our customers and partners remains steadfast, our execution to fulfill commitments is flawless, and our progress against strategic objectives remains focused.

Well, there you have it.  This effects such things as Harris transmitters (AM, FM, TV, HF) and support, Harris consoles and studio furniture (previously Pacific Recorders and Engineering or Pacific Research and Engineering, AKA PR&E), Intraplex STL systems, among others.

What does all this say about the future of terrestrial broadcasting?

We live in interesting times.

The Broadcast Electronics FW-30 automatic exciter switcher

This is a neat piece of kit, designed to save those late night/early morning call outs, which is the ultimate goal of all broadcast engineers, or at least it should be.  This seems like a really good idea, however, BE has discontinued the product line, the last manual update is from 2000.

Broadcast Electronics FW-30 exciter switcher innards

Broadcast Electronics FW-30 exciter switcher innards

A small four port coax switch is located next to the power supply transformer.  This is controlled by the circuit board.  The circuit board senses loss of excitation by detecting a forward power level below the threshold set on the board. The power sample comes from the exciter forward power remote metering terminals.  Thus, it can be used with any exciter(s) that have a remote forward power sample.

BE FW30 exciter switcher block diagram

BE FW30 exciter switcher block diagram

The idea is to use the RF fault function output of the FX-30 (later FX-50) exciter to automatically switch from a faulted exciter to one that is working.  Finally, it can be hooked to a remote control for manual switching.  The un-used exciter is muted and routed to a dummy load mounted on the back of the unit.

Broadcast Electronics FW-30 front, mid 1980's BE blue

Broadcast Electronics FW-30 front, mid 1980's BE blue

An alternate configuration would be to route the backup exciter to the backup transmitter instead of the dummy load.  This would create the best redundancy on a limited equipment budget.  It also has a battery bank designed to hold the last state of the unit through a power outage.  As we have a good sized UPS powering the remote control, STLs and satellite receivers, the batteries are not needed.

On the face of it, a pretty good idea.  I have had a few exciters fail over the years, which normally means the backup transmitter is placed in service by remote.

I did download the manual, but since it is currently listed on the BE website, it’s probably not a good idea to post the schematic.  Suffice to say, it is a tad bit complicated what with all the CMOS logic and that.  It is very possible to duplicate the functions of this equipment with a simple RF forward power sample and set a failure threshold with a comparator circuit.  Hook that to a small four port coax switch and a couple of RF mute/un-mute commands to each exciter and: Viola!  Automatic exciter switching!

Perhaps a good rainy day project.

The Harris Z6HD transmitter

These transmitters are good.   They seem to behave in a mostly normal manner, having a few quirks now and then. This particular unit is installed at WFAS-FM in White Plains NY.

Harrsi Z6HD transmitter, WFAS-FM, White Plains, NY

Harrsi Z6HD transmitter, WFAS-FM, White Plains, NY

I believe the reason for the installation was for the HD Radio® that was in it.  The Deathstar HD Radio® exciter is in the next rack over.  No further comment needed.

On this day, the transmitter had given up, throwing a main fan fault.  The fan (blower) motor had been replaced in the last six months (on a transmitter that is only five years old), so it was not that.  As it turns out, the stock fuses; 10 amp, slow blow, were just a little bit underrated for the job.  Harris released a service bulletin a few years ago calling for 15 amp slow blow fuses as replacement.  In any case, it was an easy fix and now there is a box of 15 amp slow blow fuses in the transmitter next to the fuse holders.

Harris Z6HD transmitter front RF modules

Harris Z6HD transmitter front RF modules

The modules are accessible by the front and rear of the transmitter.  These doors can be opened with the unit is on the air, since all of the high voltage is in the bottom of the transmitter where the blower is located.

Module in the middle is the IPA.  Each module has two RF amps, each RF amp has two devices (BLF-177).  The devices are field replaceable, however, on the HD models, one has to make sure that the amplifiers are still linear.  On the non-HD models (Z6CD), this is not a problem at all.  Shorted MOSFETS will be noted by a fault of one entire power supply.  Removing the bad RF module will allow the transmitter to run at somewhat reduced power.  Finding the bad module may take a bit of trial and error.

Harris Z6HD transmitter back

Harris Z6HD transmitter back

The back of the transmitter has the directional coupler, low pass filter,access to the back of the analog exciter, controller and remote control connection points.

The power supply in the bottom of the transmitter has multiple taps, each on with its own fuse.  These can be a bit of a chore to work on.  There is also a ribbon cable that goes from the controller to the power supply board.  This is directly in the path of the cooling fan and can flop around causing the conductors in the cable to break.  The result is the power supply may not come on, or may show an unbalanced power supply condition (in the case of a three phase transmitter).  Very difficult to diagnose.

Harris Z6HD transmitter, on air, WFAS-FM, White Plains, NY

Harris Z6HD transmitter, on air, WFAS-FM, White Plains, NY

Here it is, running again.

The hard restart

Sometimes there is just no way around it, especially with some modern equipment:

Hard restart, Nautel VS2500 transmitter

Hard restart, Nautel VS2500 transmitter

This Nautel VS2500 transmitter got all cranky after lightning struck the tower (or nearby) on Friday night.  Thunderstorms in February are not unheard of, but they are unusual, at least in the Northeastern United States.

Nautel VS2500 FM transmitter, WBEC-FM, Pittsfield, MA

Nautel VS2500 FM transmitter, WBEC-FM, Pittsfield, MA

Anyway, the transmitter would not reset or restart via remote control, therefore, we had to ride the chair lift to the top of the hill and pull the plug to reset its logic and start over again.

Bousquet Ski Area Chair lift

Bousquet Ski Area Chair lift

At least the trip up to the transmitter site was scenic.  We had to wait a day for the winds to calm down, but all in all, not a terrible day.  Did I mention the scenery?

Work ethic

We have this guy that works for us who is atypical. We call him Pete because that is his name.  The other day, he was slacking off on the job again, this time figuring out how to take a nap in a transmitter:

Pete working on a Harris FM25K

Pete working on a Harris FM25K

What are we going to do with him?

Actually, he is rebuilding the grid tuning section (AKA input tuning section), which is no small matter.  Soon, we will have this 26 year old transmitter running good as new, or better than new.  It already sounds much better on the air than it did before, the input tuning is broader and there is much less AM noise.

Currently, it is running about 70% power while we wait for a replacement amplifier from Silicon Valley Power Amps.

WRKI WINE transmitter move, update 2

Man, this is taking longer than I though it would. We moved the Harris FM25K last week, all went well. The only hangup, as you can see, is the harmonic filter and the height of the racks next to the transmitter. The transmitter had to go on a 4×4 to get the filter up over the racks. The output from the transmitter to the harmonic filter cannot be changed in any way, shape or form (e.g. adding a little bit of line section to the top of the transmitter), else the transmitter will not run. So, up on 4×4’s it is.

WRKI WINE transmitter room

WRKI WINE transmitter room

There we were, all ready to turn the transmitter on.  Press the high voltage on button, lots of volts but no current and no power output.  Seems something is wrong with the outboard IPA driver (over in the bottom of the rack, that thing pulled out with the manual on it).

The IPA is a Silicon Valley Power Amplifier 500 watt unit, which replaced the internal IPA driver about ten years ago.  The tube in the Harris FM25K needs at least 390 watts to drive the transmitter to full power.  Unfortunately, this particular amplifier was not in the best environments prior to the recent move.  It was sitting in an unconditioned building on top of the backup transmitter in high heat and humidity.  According to the manufacture, such abuse is bound to take it’s toll sooner or later. The later being, of course, the night we want to turn the thing back on and go home.

Time to drop back and punt.  I found an old RVR 250 watt amp at a sister station nearby, which was also in pretty bad shape but repairable.  That unit was pressed into service temporarily and with 200 watts drive, the old 25K put out about 11 KW.  We need to affect permanent repairs to the RVR power amp before we place into temporary service.  I don’t want any 2 am phone calls.  The Silicon Valley Power Amp needs to have the amplifier module sent back to the manufacturer and rebuilt.  They will refurbish the entire thing for something like $900.00 plus shipping.  Considering what it does, that is worth it.

This is a little short cellphone video of the turn on at half power.  This is a very loud transmitter, as such, I think the audio is a little distorted.

When this beast gets up to full power, I will update this, again.

Axiom


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

Free counters!