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Harmonic Filter for BE FM-30T

Another example from my blown up shit collection, pictures archive:

Burned out harmonic filter, BE FM-30T transmitter

Burned out harmonic filter, BE FM-30T transmitter

The harmonic filter from a Broadcast Electronics FM-30T.  This actually started in the bullet connector to the 3 inch hardline on the output side of the filter.

Burned out 3 inch hard line section

Burned out 3 inch hard line section

Again, I did not install this myself, someone else did.  Cutting 3 inch hard line is pretty straight forward.  When using a field flange, the outer and inner conductors are cut flush.  Both conductors should be de-burred and filed smooth.  It only takes a little thing to start an arc with 30 KW of FM power, so once again, attention to detail is key to avoiding these things.

Fortunately, BE sent along replacement parts for the harmonic filter and the line section was replaced.

AM transmitter site maintenance check list

As promised, here is the AM transmitter site maintenance check list.  This is for a generic directional AM station with a backup transmitter, generator and an RF STL.

Broadcast Electronics AM6A transmitter

Broadcast Electronics AM6A transmitter

Usual disclaimers apply.

AM site Maintenance checklist

Weekly Maintenance:

A.  Visit site, Check following:

  1. Check critical transmitter values against last logged value
  2. Check forward/reflected power on main transmitter
  3. Check and reset any overloads
  4. Check signal strength on STL against last logged value
  5. Check generator fuel level
  6. General check of building, look in all rooms, inspect for damage from vandalism, Leaking roofs, obvious signs of trouble, take steps to correct.

Monthly Maintenance:

B.  Visit site, Check following:

  1. Do a full multi-meter log, (includes tower phase angles, loop currents), run backup transmitter into dummy load.
  2. Start and run generator for 5 minutes, check block heater, hoses, belts, oil and antifreeze levels
  3. Calibrate remote control meters with transmitter meters, log it*
  4. Check all tower fences for integrity and locked gates*
  5. Complete Items 3, 4 and 5 under weekly maintenance.

Quarterly Maintenance:

C.  Visit site, Check following:

  1. Complete 1 through 5 under monthly maintenance.
  2. Check all air filters, clean or replace as needed.
  3. Check frequencies of all transmitters, STL receiver, and log.
  4. Complete quarterly tower lighting and painting inspection*

Bi-yearly Maintenance:

D.  Visit site, Check Following:

  1. Complete 1 through 5 under quarterly maintenance.
  2. Conduct monitor point readings for all directional antenna patterns*
  3. Check base current readings for day/night towers.  Ratio.*
  4. Clean backup transmitter
  5. Place backup transmitter on air and clean main transmitter.

Yearly Maintenance:

E.  Check all licenses and authorizations for accuracy. Make sure that all renewal cards etc are in public file and are posted at control point.*

F.  Visit site, Check following

  1. Complete 1 through 5 under Bi-yearly maintenance
  2. Equipment performance measurements (NRSC, Harmonics, frequency)*
  3. Complete service of generator
  4. Complete Inspection of towers, check for vertical and plumb, check guy wire tensions, retension as needed.
  5. Check property for anything out of the ordinary
  6. Repair driveway as needed

General maintenance that is completed on an as needed basis

  1. Re-fill fuel generator fuel tank when drops below 50 percent
  2. Empty trash, sweep floors, dust.
  3. Cut/remove vegetation inside tower fences, spray herbicide as needed
  4. Water proof tower fences every 2 years
  5. Paint exterior of building
  6. Replace tower lights*
  7. Paint towers*

*These are FCC inspection items, pay close attention if you do not want a fine.

That is it, a .pdf version of this file can be downloaded here.

WOVV, Ocracoke, North Carolina

Community radio station WOVV signing on:

They are not there yet, according to their web site, anticipated sign on is not until spring of 2010.

Remember when all radio stations were community radio stations?  The CNN report now calls this “old-style radio.”  It is sort of funny how these little radio stations, built mostly by volunteers with donated money, get it. A radio station is supposed to be about community service. It is sad that broadcasters with both the means and methods to reach these isolated people have ignored them.  Because, you know, there is very little money in community service.

BE AM5E power supply problem

This is from my burned out shit collection, pictures section:

Broadcast Electronics AM5E power supply

Broadcast Electronics AM5E power supply

It is a power supply from a Broadcast Electronics AM5E transmitter.  Here is another view:

Broadcast Electronics AM5E power supply mating connector

Broadcast Electronics AM5E power supply mating connector

As you can see, there was a small fire started in the mating connector for the transmitter wiring harness.  I did not install this unit so I have no way to know for sure what happened, but I suspect that the mating connector was not pushed all the way in during installation.  In this business, really in all engineering fields, it is the little details that will catch up with you.

I know that one of the stations I used to work at had a fire at their electrical service panel at the FM transmitter site, after they installed a new transmitter.  This happened after I departed for greener pastures.  In any case, it is very important to torque the connections on any service disconnect or circuit breaker to the panel manufacture’s specifications.  I also check the lugs every so often with a Fluke 62 mini IR temperature meter. Any loose connections will show up as hot spots, which can be fixed before the fire breaks out.

All current carrying electrical connections should be double checked for solid connections before the transmitter is turned on, then check periodically thereafter for heat buildup and or heat damage.

FM transmitter site maintenance check list

I developed these check lists for FM transmitter site based on experience and what needs to be checked, how often it needs to be checked and what else can go wrong.  This checklist is for a generic FM transmitter site with a back up transmitter and an RF STL.  Every site is different, so some things on this would likely need to be changed or adapted depending on equipment and other facilities.

BE FM20T transmitter

BE FM20T transmitter

Enjoy!

Weekly Maintenance:

A.  Visit site, Check following:

  1. Check critical transmitter values against last logged value
  2. Check forward/reflected power on main transmitter
  3. Check and reset any overloads
  4. Check generator fuel level
  5. Check the STL signal strength level against last logged value.
  6. General check of building, look in all rooms, inspect for damage from vandalism, Leaking roofs, obvious signs of trouble, take steps to correct.

Monthly Maintenance:
B.  Visit site, Check following:

  1. Do a full multi-meter log, run backup transmitter into dummy load.
  2. Check line pressure, Check tank pressure and/or desiccant for water
  3. Start and run generator for 5 minutes, check block heater, hoses, belts, oil and antifreeze levels
  4. Calibrate remote control meters with transmitter meters, log it*
  5. Check the tower fence, be sure it is secure and locked.*
  6. Complete Items 3, 4, and 6 under weekly maintenance.
  7. During summer months, be sure the vegetation is cut around building and tower.

Quarterly Maintenance:

C.  Visit site, Check following:

  1. Complete 1 through 7 under monthly maintenance.
  2. Check all air filters, clean or replace as needed.
  3. Check frequencies of all exciters, STL receivers, TSL transmitters and log.*
  4. Complete quarterly tower lighting and painting inspection

Bi-yearly Maintenance:

D.  Visit site, Check Following:

  1. Complete 1 through 4 under quarterly maintenance.
  2. Clean backup transmitter
  3. Place backup transmitter on air and clean main transmitter.

Yearly Maintenance:

E.  Check all licenses and authorizations for accuracy, make sure all license renewal cards are posted and placed in the public inspection file.*

F.  Visit site, Check following

  1. Complete 1 through 3 under Bi-yearly maintenance
  2. Complete service of generator
  3. Complete Inspection of tower and antennas, check concrete tower bases, check guy wire anchors, (grounding, turnbuckle safety cable) check property for anything out of the ordinary
  4. Repair driveway as needed

General maintenance that is completed on an as needed basis:

  1. Tube changes on main/backup transmitter.
  2. Sweep antenna with a spectrum analyzer/return loss bridge to make sure it is on frequency and has sufficient bandwidth to pass FM signal.
  3. Look at FM RF mask with spectrum analyzer, check harmonics for proper attenuation.
  4. Sweep transmission line with a spectrum analyzer/return loss generator.
  5. Re-fill fuel generator fuel tank when drops below 1/2
  6. Empty trash, sweep floors, dust.
  7. Paint exterior of building
  8. Replace tower lights*
  9. Paint towers*

*These are FCC inspection items, pay close attention if you do not want a fine.

The .pdf version can be downloaded here. I’ll to an AM directional check list next week.

Nautel V-40 FM transmitter

Yesterday, I threw out a transmitter.  I know there is probably some radio station out there that may have been able to use a 5 KW FM transmitter, but believe me, not that one.  There are limits to how much you can help out a fellow broadcaster.  Donating an FM transmitter that never really worked right in the first place is counter productive.

Anyway, to demostrate that I am not a total heel, here is my favorite brand of transmitter, Nautel:

Nautel V-40 transmitter (4 V-10 transmitters combined)

Nautel V-40 transmitter (4 V-10 transmitters combined)

I like Nautel because they are rugged, reliable and good looking.  Okay, good looking is low on the list of transmitter attributes, however, you have to admit, it is good looking.  It is also good sounding.  The night we switched over from the long in the tooth BE FM30A to the Nautel V-40 I noticed a marked improvement in the station’s sound.  It was like somebody switched off the background noise generator.

As the caption states, this is 4 V-10 transmitters combined with a ERI magic T combiner.  It is set up so that if any one transmitter fails or reduces power, the magic T combiner automatically adjusts for minimum rejected power, then the SC-1 controller turns up the other three transmitters to maintain the stations Transmitter Power Output (TPO).

TPO 28 KW

TPO 28 KW

In this case the TPO  is 28 KW, which is getting into the semi serious range for an FM station.   Nautel has updated their transmitter line, which now consists of the NV series transmitter.  The differences mainly have to do with the IPA module/PA module interchangeability (not interchangeable in the V series, fully interchangeable in the NV series) and the “Advanced User Interface.”  I don’t know, fancy touch screens are optional on FM transmitters as far as I am concerned.  It’s the underlying RF generating sections that I am most concerned about.

Nautel V-40 transmitter

Nautel V-40 transmitter

Another view.  Just for the useless trivia that is in it, the “V” in these transmitter names stands for “Virtuoso.”

Gates FM5G transmitter

Takes its rightful place in the world today, the scrap heap:

Gates FM5G carcass

Gates FM5G carcass

As EDWARD I of ENGLAND once said, “A man does good business to rid himself of a turd.”

Of course, he was speaking about Scottsman John Balliol and not some old cranky FM transmitter, but I understand that feeling.  The Gates and later Harris transmitters always seemed to be somewhat less than top notch. The 5G was no exception to this rule.  The final step for tuning the transmitter was to turn off the lights in the room and look down through the screen on top to make sure there were no little arcs in the PA tuning section.  It also had a way of self oscillating, which could make for some exciting tuning.

Gates FM-5G transmitter prior to disassembly

Gates FM-5G transmitter prior to disassembly

Good bye, I will not miss you.

In one of my past jobs, I worked in a RCA town.  I worked there long after the broadcast arm of that company went out of business, however, all of the broadcast transmitters, AM, FM, TV were made by RCA.   I had an RCA FM-20ES1 which was 22 years old, built like a tank and just kept going along.  I think that transmitter was finally destroyed in a fire, caused by it’s replacement transmitter.

Old Collins, Contenental, RCA and even Broadcast Electronics transmitters had some heft to them.  Of course, not every RCA transmitter was well thought out, the amplifuze series of AM transmitters were a maintenance nightmare.

Radio is dead/Radio is not dead

I have been reading with interest the whole debate about radio being dead or dying vs. radio being a vibrant thriving business.

FM-analog-tuning-indicator

Radio is not dead by any measure, however it is declining for a number of obvious reasons.  There are more competing entertainment and information options, that is true.  Ipods, netcasters, satellite radio have taken some of radio’s listeners away.  However, the main culprit in radio’s decline are the investment bankers that are squeezing every drop of blood nickle out of the industry before moving on to their next victim investment opportunity.

The net result of this has made much, not all, of radio predicable and boring.  No longer is radio the source for new music, news, information and entertainment as it used to be.  I don’t think that anyone will argue that point.  The money men have fired most of the creative and talented individuals who used to bring in the listeners and replaced them with computers.  They have also cut news staffs, support staffs and anything else that lives and breaths except sales people.  More sales people are always required.

HD RadioTM radio is a joke at best.  Setting aside all of the technical problems with coverage and building penetration, the programming sucks too.  The same purveyors of crap on the main analog channels are now branching out on the HD2 and HD3 channels.  I can’t believe that the secondary channels will somehow be better than the main analog channels,  or even marginally good enough to buy an HD Radio radio.  Some groups are putting their AM programming on an FM HD2 channel, which is great if one cares to hear drug addled corpulent talk show hosts wheezing into the microphone in full fidelity.   At least on the AM analog broadcasts, everything above 4.5 KHz is cut off, wheezing included.

The good news is, there are still some radio stations that are programmed well.  Radio sets are almost universal, every car has one, every house has at least one or two, most offices, stores, etc. Radio reception is still free.  Radio is still popular among many people.  Radio owner’s could very easily become involved with their communities of license, make better programing decisions, hire staffs, and add valuable informative local programs again.  This decline would soon be forgotten.

The bad news is that is unlikely to happen.  Less than a snowball’s chance in hell unless someone wakes up and smells the coffee.

I am half an optimist.

The lesser of two evils

If I had to pick between allowing HD RadioTM a 6 dB increase or removing the third adjacent protection for LPFM stations, I’d choose LPFM.

In tests performed by NPR, Ibiquity’s In Band On Channel (IBOC) digital radio scheme created significant interference to the first adjacent channel when running with 6% of the analog carrier power (-14 dB referenced to carrier) vs. the 1% (-20 dB referenced to carrier) currently allowed.  The NAB has would like to see -10 dB referenced to carrier or 10% of the analog carrier power.

Remember Bill Clinton’s sign during his first election, something about the economy, stupid.  In this case, it’s the Bandwidth, Stupid.  In the US and Canada, FM stations are allowed 200 kHz of spectrum to transmit their analog signals.   Analog signals include main channel mono (left plus right), and sub channels for stereo pilot (19 kHz) stereo matrix (left minus right), RDS (57 kHz) and any subcarriers in the 67-92 kHz range.

HD RadioTM radio requires 400 kHz of spectrum to transmit it’s digital carriers.  Here come those laws of nature again, you can’t fit 400 kHz bandwidth into 200 kHz of spectrum.

Ibiquity decided to try it anyway, contravening the FCC’s rules about FM broadcasting bandwidth channels which had been in place since the advent of FM broadcasting in the early 1940’s.  What they attempted to do was make the power level on the adjacent channel so low that most analog radios would not have a problem with it while there was a strong signal from another station present.  (hey buddy, how about a little of this new thing called crack?) This is known as the capture effect.

Now, Ibiquity created this whole thing to make some money.  Nothing wrong with that, this is a market economy after all.  They marketed the hell out of HD RadioTM radio, I saw them at various trade shows, they had full page advertisements in all the trade magazines, they hit the phones, it was a full court press (it’ll make you really cool, you’ll be able to do things you can do now and you’ll feel really good).  They would even reduce or waive the license fee (here, just take a little rock, try it, on me, you’ll see).

So they were able to sell a very expensive system that has significant coverage issues because of the low power levels needed to satisfy the FCC’s concerns about adjacent channel interference.  The NAB and many of the big radio groups bought in to it (gotcha, crackhead, you’re mine now).

Now, of course, those that bought into HD RadioTM radio want their investment to work, (which it doesn’t right now) so all the talk of power increases and hey, lets just disregard that pesky interference issue.  If you ignore it, eventually it will go away (along with the entire FM band).

The problems with HD RadioTM radio are:

  1. Inadequate building penetration at the current power level (1% of carrier power)
  2. Bandwidth that exceeds current channel assignments on both AM and FM frequencies.
  3. Proprietary nature of HD RadioTM‘s CODECs and licensing for second channels give Ibiquity too large a role saying how radio is broadcast in the US.  Remember, radio station licenses are granted in the public interest, the owners are trustees of the public
  4. Complete lack of public awareness.
  5. It doesn’t really improve anything anyway.

By the way, shame on NPR (again) for their corporate stance contrary to maintaining good quality radio and serving public interest.

Compared to that, LPFM is a very minor thing.  As I said before, removing the third adjacent protection will raise the noise floor in the FM band and by default cause more interference.  However, I’ll take a little more interference created by community radio stations over the complete rack and  ruin of the FM band.

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

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