The Pacific Records and Engineering BMXII console

I snapped these pictures at WICC in Bridgeport, CT. It is an older PR&E BMXII console, with 26 channels, I believe.

Pacific Recorders BMXII 26
Pacific Recorders and Engineering BMXII 26

These were manufactured starting in 1985, I installed one in 1990. It is a testament to their durability that this one has lasted 23 years.  They were expensive when purchased, and all of them were purchased directly from PR&E, Carlsbad, California.  The beauty of these things is their modularity.  All of the major components are replaceable, including the module face inlays.

Penny Giles conductive plastic fader
Penny Giles conductive plastic fader, PRE BMXII console

The faders, Penny and Giles 4000 series, are fully rebuildable.  The part that wears out the most is the nylon bushings that slide along the metal rails.  The contact fingers sometimes also need to be replaced.  These are 10 Kohm conductive plastic linear faders.  P&G does not make these anymore, they have been replaced by the 8000 series, which has an edge connector instead of a wiring harness.  Since the top of the fader is open, it also tends to accumulate dust, dirt, and other debris.  The fader board itself should be cleaned off with warm water, light soap may be used if needed.  Do not use alcohol on these because it eats into the conductive plastic and ruins the fader.

PRE BNXII line input module
PR&E BMXII line input module

One of the great things about this console is the fact that all the modules are hot-pluggable.  If one needs to be serviced, it can be pulled out of the main frame while the console is on the air and a new module plugged into it’s place.  Only the line output module replacement necessitated taking the station off the air, and then only for a few seconds.  It was a great concept that is now standard in almost every broadcast console.

There were several basic module configurations.  On the input side, line level, mic level, and telco were standard console inputs.  There was also a passive remote line select button set.  Out put modules consisted of line-level output, control room monitor, and studio monitor modules.

PR&E consoles were top-of-the-line gear, but expensive.  Most radio stations could not afford them and went with less expensive models like Wheatstone, BE, LPB, Autogram, Radio Systems, etc.  The fact that some of these BMXII consoles are approaching 30 years of age and still in service is a testament to their construction.

In the early 1990s, PR&E began branching out into the lower priced market with their product line.  They produced the Radiomixer and Productionmixer consoles, however, mid-market-sized radio stations were slow in adopting them because PR&E had the reputation of being expensive.  After all, if you can only afford a Chevrolet, why bother looking at the Mercedes?

WQXR control room
WQXR control room

This is a grainy promotions photo from the early 1990s showing what I think is the WQXR master control room, nick named “The Bridge.”  I took a tour there around 1993 or so and it was a fantastic facility, of course, the New York Times spared no expense.  I really felt like Willie Wonka in the Chocolate factory.

Later in that decade, they changed the name to Pacific Research and Engineering, and the went public.  I think going public was the death knell, soon thereafter they sold the entire product line to Harris Broadcast.  The final non-Harris console was the Airwave, which is a good medium-duty modular console, incorporating some of the traditional PR&E designs.  The later consoles stopped routing audio directly through the faders, using voltage-controlled amplifiers instead.  This solved some of the channel drop out problems that sometimes occurred in earlier consoles.  The Airwave consoles are much less durable than the BMX series, however, with the advent of voice tracking, perhaps 24/7 durability is not that necessary anymore.

Harris has dropped support of much of the early PR&E line, but there are those that soldier on, buying up parts and rebuilding these things.  Mooretronix has a good selection of BMX and ABX parts.

The WICC/WEBE  installation is about to be refurbed, which means these consoles will be headed out the door.  There are three of them in fair condition.

Digital Radio: A solution without a problem

Or, it could also be phrased “A solution that causes more problems.”  Radio World, once again, has a good article on the consequences of increasing IBOC power of the FM hybrid system.  Especially telling is figure 24, a fuzzy 400 Hz sine wave showing how much distortion is added to the analog signal by a mere 4% HD  signal.  I’d be especially interested to see the results of the full 10% now allowed.

Naturally, HD proponents will cry “But this is only temporary!  Wait until the transition to all digital!”

Bunk.

If HD radios were indeed flying off the shelves as iBiquity claims, and if the public expressed interest, okay, maybe.  Clearly, that is not the case.  The only thing that HD radio is doing is creating more interference. Period.  More interference to the parent station and more interference to the adjacent channels all for an audience that does not exist.   Another way to put it: NOBODY IS LISTENING.  One of the stations that I service had a Harris Deathstar go offline for four days.  NOT ONE PHONE CALL, NOBODY CARES!

The public did not perceive a technical problem with analog FM broadcasting.   Of course, that can always change as the band gets filled with interference.

Let’s see where FM IBOC stands:

  • Rolled out with 1% digital power vs analog carrier, the system was found to lack building penetration and generally performed poorly in mobile listening environments (NPR labs study, Nov 24, 2009)
  • FCC allows up to 10% digital power vs analog carrier to overcome these problems, a few stations implement some type of power increase
  • This shows that self-interference is the largest problem IBOC needs to fix, one that is un-fixable due to the laws of physics
  • The public yawns, turns on their iPod

IBOC is a failure, both in AM and FM bands.

We are watching the self-destruction of radio broadcasting in the US.

WSPK antenna replacement, part I

WSPK is located on North Mt. Beacon, which is the highest point for miles around. It has a fantastic signal. The site is a little difficult to get to, however, especially in the winter.  In previous years, the road has been impassable four months out of the year.  Some engineers have hired a helicopter to get up there when the snow is deep.  For that reason, it is important to keep the equipment in good shape.

WSPK Shively 6810 antenna with damaged top radome
WSPK Shively 6810 antenna with damaged top radome

After last February’s snow/rain/ice storm, it was noted that the top antenna radome was missing its top.  A tower climber was sent up to look at it and it was also discovered that the top bay was bent down and the element was almost cracked in half.  A result of falling ice, likely from the big periscope microwave reflector (passive reflector) mounted above it.

WSPK tower
WSPK tower

The periscope reflectors went out of service in 2007, but the tower owner did not want to pay to take them down, thus a problem was not being solved.   It was decided to replace the 25-year-old Shively 6810 antenna with a new one, during which work, the radio station would pay to remove the reflectors from the tower.  In exchange for that work, the radio station would then be able to repair and remount the old Shively antenna below the new one, thus having a backup antenna.  Problem solved, except for, you know:  The actual work.

The tower and the periscope microwave system were installed in 1966, operated on 12 GHz, and were used by the Archdiocese of New York to relay their educational television programming from their Yonkers headquarters to the various schools in the Hudson Valley.  Sometime around 1975 or so, the FCC mandated that periscope microwave systems could no longer be used due to all the side lobes and interference issues they caused.  They were to be taken out of service as soon as possible.  The Catholic Church, being a multi millennial organization figured “as soon as possible” meant within the next fifty years or so.  Anyway, somebody else needed that frequency, therefore in 2007, they bought the Archdiocese a new digital microwave system.

The problem with the reflectors; they are big.  They are also heavy, and present a huge wind area.  They are also 300 feet up in the air.

WSPK tower periscope reflectors seen from ground level
WSPK tower periscope reflectors seen from ground level  

Finding a day with lite winds on top of Mount Beacon can be a problem.  Luckily, the weather was with us.  Still, it took a while to get this work moving along.  The other consideration is RFR and tower climber’s safety.  There are two digital TV stations, WSPK, several cell carriers, something called “Media Flow,” and a bunch of two-way radio repeaters.  The main concern was WSPK, the DTV, and Media Flow since the top of this tower is right in the aperture of those antennas.  All either went way down in power or off the air while this work was ongoing.

Rigging a gin pole and getting it to the top of the tower was a chore.  The gin pole needed to be threaded through those torque arms like a needle.

Gin Pole
Gin pole

The tower riggers truck had two winches, one a basic 120-volt capstan, the other a hydraulic winch in the bed of the truck with 1/2 inch steel cable.

Tower rigger's truck
Tower rigger’s truck

The bolts holding the reflectors in place had to be cut with a saw, you can see the tower climber working on the left-hand reflector, which gives you an idea of size.  If this reflector were to fall off the tower, chances are good that major damage and or injuries would result on the ground.  Proceed with extreme caution.

Cutting bracket mounting bolt on periscope reflector
Cutting bracket mounting bolt on periscope reflector

Carefully lowering reflector past Shively 6810 FM antenna and Scala PR-950U microwave antenna.  During this phase, the tower climbers had to push the reflector out away from those obstacles with their legs.  You can see the gin pole at the top of the tower.

lowering periscope reflector
Lowering Periscope reflector

Another view:

Lowering reflector
Lowering reflector

Another view:

Lowering reflector
Lowering reflector

Almost down to the ground.  This measured 15 by 10 feet and ended up weighing 830 pounds.

Reflector almost to the ground
Reflector almost to the ground

One down, one to go.  I can’t believe those gigantic things were at the top of this tower, on the top of this mountain for 43 years and the tower is still standing.  This is going to change the appearance of the mountain top from down below.  For years, it looked like a pair of mickey mouse ears, now it will only look like a tower.  I wonder what the environmentalists will think.

I will make a second post with the antenna pictures as this one is getting a little long.

Care and feeding of Propane Fueled Generators

Broadcasters historically have tried to remain on the air during emergency events like major storms, earthquakes, and other forces of nature.  Oftentimes, commercial power is interrupted, and thus, the backup power generator is installed.  Propane-powered generators for medium duty (power up to 45 KW) are popular because of the decreased environmental hazards, availability and expense of fuel, and ease of maintenance and repair.  This sized generator can run the critical loads of a studio facility or a transmitter site with TPOs between 5 and 10 KW.

Katolight 45 KW generator w/outside housing
Katolight 45 KW generator w/outside housing

Most propane generators use a gasoline engine modified to use propane.  These generators can also use natural gas, however, because natural gas has slightly less energy, the generator’s service rating is reduced by about 10 percent.

Ford inline 6 cylinder engine
Ford inline 6 cylinder engine

The biggest error I consistently see with propane generators is improper fuel tank sizing.  It might seem just fine to plop a 500-gallon tank down next to a 45 KW generator and expect everything to be just fine.  500 Gallons may sound like a lot of fuel, but the more important consideration is tank vaporization, that is to say, how fast the liquid propane can be removed from the tank for use.  Propane fuel companies should be able to size these things correctly, most of them have books and charts that tell what capacities and sizes are needed.  However, as a general troubleshoot guide, the following information is provided:

Generator manufacturers will specify how many BTU per hour a generator will require under full load. If not, these are some conservative rules of thumb:

  • For every 1 KW of electrical generation, 2 horsepower of the engine is needed*
  • Under full load, each horsepower will consume 10,000 BTU per hour*
  • Propane has 92,000 BTU per gallon
  • Propane weighs 4.2 pounds per gallon

*Note: These are not the figures you will find in your engineering handbooks, they are adjusted for generator winding and engine efficiency.

Propane Tank Vaporization Rates (Continuous BTU/hr vs volume at tank temperature):

Size propane in a tank (assumes 1/3 full)Maximum continuous BTU/hr at degrees F
20°40°60°70°
120129,600188,640247,680308,160338,400
150146,880213,790280,700349,200383,520
250253,800369,400485,000603,480662,700
325321,300467,670614,000763,900838,900
500396,270567,700757,300942,2401,034,700
1000708,4801,031,2301,353,9801,684,6001,849,900
1450816,1201,253,4001,645,6902,047,5502,248,480

Note: Tank vaporization depends on fuel level, tank temperature, and withdrawal rate.  The above chart is a conservative generalization and represents a safe median value.

If a propane tank cannot vaporize fuel fast enough, the generator will begin to run lean, eventually overheat, and shut down. The vaporization rate depends on the tank temperature, which drops as fuel is withdrawn.  For the above-cited 45 KW generator called to duty after a severe winter storm, the tank would need to vaporize: 45KW x 2 HP = 90 HP.  90 HP x 10,000 BTU/hr = 900,000 btu/hr.  A 500-gallon tank is too small for that size generator.

As the tank temperature drops a propane tank can develop frost on the outside of the tank, even on a hot summer day, which compounds the problem.

The correct size tank for a 45 KW generator is 1000 gallons.  This can also be two five-hundred-gallon tanks connected in parallel via a high-pressure line.

45 KW propane generator with two 500 gallon tanks
45 KW propane generator with two 500-gallon tanks

Also note, the generator’s radiator is facing the tanks so that when the unit is running, hot air is blowing on the tanks, warming them up.  This particular generator is about 25 years old, which is why it looks a little worn.  It still carries the load and mechanically is in sound condition.

Most propane fuel systems have two regulators; one high-pressure regulator on the tank, which takes the variable tank pressure and steps it down to about 10 PSI, and the vaporizer which steps the pressure down to a few ounces per square inch (or inches of water column) and adds air creating propane gas for the generator to burn.

High pressure propane tank regulator
High-pressure propane tank regulator

It is important that the vaporizer be mounted above the snow line and that there is a little screen on the air intake, otherwise, mud wasps will build a nest in the air intake and the next time the generator is required to run, it won’t start.

Low pressure propane regulator/vaporizer
Low-pressure propane regulator/vaporizer

Fuel piping is also a concern, if the low-pressure lines are not large enough to handle the required BTU, the generator will run lean, creating the same problems as an improperly sized tank.  Different piping has different capacities, see the following charts:

Propane steel pipe sizing diagram
Propane Schedule 40 steel pipe sizing diagram
Propane copper pipe sizing diagram
Propane copper-K pipe sizing diagram

Assumes pressure less than 1.5 PSI, one MBTU is equal to 1,000 BTU per hour.

Once the generator is installed, maintenance is required.  As a minimum:

  • Exercise the engine bi-weekly for 15 minutes. Propane generators do not need to run under load.
  • Check fuel, oil, and antifreeze levels monthly, more often if heavy use.
  • Change the oil, oil filter, and air filter, and check the antifreeze freeze point, and battery electrolyte specific gravity yearly
  • Change out belts and hoses as needed, and pay close attention to the block heater hose, this is where leaks often develop
  • Clean out mice nests and droppings as needed

Mice love generators.