How much is prevention worth?

I sometimes get the distinct impression that the corner office doesn’t understand what it takes to keep a radio station on the air and in good repair.  It is most often the problems or “issues” that tend to get the most attention.  The things that are working well tend to get ignored. After all, how often do you hear a news report about the airliner that landed safely.

Lightning strike TV tower
Lightning strike, TV tower

When lightning strikes the tower and knocks the transmitter off the air causing major damage and expensive repairs, that is a problem.  When lightning strikes the tower and nothing happens, no problem.  What is the difference between those two situations?

Grounding strap, FM transmitter site
Grounding strap, FM transmitter site

If the generator starts and runs during every power outage and has done so for the last five years straight, it is obviously a reliable unit, does it need all that maintenance?

Caterpillar 75 KW diesel GENSET
Caterpillar 75 KW diesel GENSET

Money spent on preventing undesirable outcomes can be difficult to quantify as disasters and events that do not happen are ill defined.   It is difficult to quantify the “amount saved” on something that didn’t or won’t occur.  Using past situations is good start, but that only covers a fraction of possible outcomes.  In order to invest money wisely, one has to look at the probabilities.  If there is an unlimited budget, then the probability exercise should be minimal, however, there is very seldom an unlimited budget.

For example, how much does a back up STL system cost vs the risk of being off the air while the main STL system is being repaired?  How often do failures occur, when are they likely to occur and for how long are all good questions.  Is there an alternative to a full back up like an IP CODEC?  Such a solution would cover all aspects of the STL system including antennas, transmission line, transmitters and receivers.

There are certain FM stations north of here that have neither RADOMES or antenna heaters.  Once every two years or so, the antenna ices up and the transmitter folds back due to VSWR.  How much of an impact to listeners notice when this happens?  If it happened more often, say two to three times a year, would it be wise to invest in some type of deicing equipment?

What is the ownership and management opinion on off air conditions?  I have often heard tell “Oh, its only the AM, we don’t mind if it goes off the air.”  That is, until it actually goes off the air, then it is a big problem.

Based on my and others experiences, these are the things that will happen at an average transmitter site:

  • The electric will go off at least once per year for several hours.
  • The main transmitter will fail at least once every two years.
  • Lightning will strike the tower at least once per year.
  • The STL system will fail, at unknown intervals.

At studio sites, these things will occur:

  • The file server will crash depending on the operating system
  • The telephone lines and or T-1 service, internet service, ISDN etc will go out
  • The electric power will go out for several hours
  • The satellite dish will fail once every two to three years
  • If there is a tower, it will get struck by lightning

Other site specific things can occur like floods, blizzards, earthquakes, fire, etc.

Money spent on backup systems for those items is good insurance.  Not only will the station stay on the air, the on call engineer’s phone will ring less often, which, if you are the on call engineer, should make you happy.

If a full backup is not available, a second transmitter for example, having a good stock of spare parts on hand can mean the difference between an early evening and an all nighter.   Keeping good maintenance logs and well documented repair records can point out trends and give a good basis for ordering spare parts.

Repair trends are important.  If the same part seems to be going bad over and over, it is time to dig deeper and find the cause of failure.

The old adage “An once of prevention is worth a pound of cure,” still holds true.

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.

The Harris MW1A

They say the first thirty years are the hardest, perhaps it is true. This Harris MW1A transmitter turns 31 this year:

Harris MW1A AM transmitter, WINE, Brookfield, CT
Harris MW1A AM transmitter, WINE, Brookfield, CT

Truth be told, these are not bad units.  They have some quirks, however, the overall circuitry is simple, the design is simple enough and parts for repair are readily available.  They require regular infusions of RF transistors, but those are easy to change and are inexpensive to buy off the shelf from places like Mouser or Allied.

It is on the air as the main transmitter for WINE-AM in Brookfield, CT.   This is Harris’s first solid state AM transmitter design, based on the work of Himmler Swanson.  This is not a PDM transmitter, rather, each module has RF transistors and audio transistors.  The output of all twelve modules are combined for a carrier output of 1,000 watts with +125% modulation.   Harris calls this PSM (Progressive Series Modulation), which is sort of high level modulation.

This is also the only transmitter that I know of where blown fuses can cause damage to the RF devices.

The RF output transistors and audio transistors are still available from Harris.  Non-OEM parts for this include the 2N5038 for the RF transistors and the MJ15011 for the audio transistor.  Inside the front of the transmitter is a row if incandescent light bulbs that glow increasingly as the various transistors go bad.  At 1,000 watts carrier power, the ratio of PA volts to PA amps is 52.5/22.5 respectively.  If that ratio is off by any measure, there is a problem.

Original sales brochure for the MW1 (no A):

Harris MW1 sale brochure
Harris MW1 sale brochure

Entire brochure available here.

Harris MW1 interior view
Harris MW1 interior view

The other thing with this transmitter is it is very sensitive to any kind of VSWR.  Any change in the output impedance will quickly make itself apparent.  My Harrisburg MW1A had two ATU settings, one for winter and one for summer.  It was a slightly tall tower on 1230 KHz, thus any change in the ground system (e.g. snow cover) would upset the tower base impedance.

The other thing that goes bad is the large Rotron fan in the bottom of the cabinet.  They go bad about every 10-15 years or so.

The owner has spent some money on this particular unit, rebuilding and replacing several modules with new transistors etc.  Will it last another thirty years?  Depends on if the RF and audio devices remain in production.

The never ending HD radio debacle continues to not end

Especially on the AM band.

Radio World, bless them, has yet another article about the public’s lack of awareness regarding HD Radio®.  Calling it “lack of awareness,” is overly kind and I think they are missing the point.  It would be better phrased “apathy” or “indifference.”

There is a general misconception in the world that one either loves or hates something.  That is not true, the opposite of love is indifference, not hate.  The public has voted, with their wallets, for things like 3 and 4G wireless devices, satellite radio, iPods and other entertainment venues.  Why?  Because HD Radio® is not an advance, it is a repackaging of old ideas with slick marketing.  The general public has viewed the great digital radio conversion with a jaundiced eye, opting to sit on the fence and wait for something better.  What has iBiquity given them?

The technology itself is a step backwards with many band aids needed to affect the same coverage area as analog FM.  A technology that has poorer building penetration, less coverage area , mobile reception issues with no appreciable difference in sound quality or program material offerings.  A power increase from 1% to 10% analog carrier power (20dBc to -10dBc) hasn’t really made a difference.  Now, studies are underway looking at asymmetrical sidebands and same frequency repeater networks for FM IBOC.  All of these things, not to improve radio reception, but rather to achieve the same coverage as analog FM.

The AM HD Radio® has even greater issues.

There is nothing at all surprising about the public indifference toward HD Radio®.