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Water and RF do not mix

Last year, the main antenna and transmission line for WSPK was replaced.  I was, therefore, somewhat surprised to hear that there was an issue with the new transmission line.  And yet, problems there are.  Most likely, some ne’er do well has shot the transmission line with a bullet making a hole, which, when it rains, allows in water.  Said water then accumulates in the bend at the bottom of the tower.  When enough water is present to fill the gap between the center conductor and the outer conductor, this happens:

Foward and Reflected power meters, WSPK, Mount Beacon, NY

Foward and Reflected power meters, WSPK, Mount Beacon, NY

For those of you keeping score at home, that’s 980 watts forward, 375 watts reflected or about 4:1 VSWR.  Obviously not a good load, in fact the transmitter shut down.  Fortunately, the backup transmitter and antenna system worked flawlessly.

This began happening last month, usually after a heavy rain storm.  Thus, I went out to the base of the tower and shook the transmission line and sure enough, water was sloshing around in there.  Last time time it happened, a tower crew was summoned to inspect the line.  Inspect it they did, but did they find any holes? No, they did not.  Perhaps the issue is with the antenna itself, in which case the entire thing will have to be removed from the tower and lowered to the ground.   In the mean time, my boss drilled a small “weep hole” at the bottom of the bend where the line comes off the tower.

I uncovered this weep hole and pressurized the line and viola, lots of water came out:

WSPK 1 5/8 inch air dielectric transmission line, Mount Beacon, NY

WSPK 1 5/8 inch air dielectric transmission line, Mount Beacon, NY

A bit unconventional, but effective nonetheless.  The first video is of the water dripping out:

The second video is of me walking back into the transmitter building to pressurize the line:

Everything is very noisy because it is Monday, when all the generators on site exercise. There are five diesel generators running while I was videoing recording this.

I would estimate about 6 ounces of water came out through the weep hole, most of it landing on the ladder underneath.  After the water was drained out, the transmitter came back on at full power and normal VSWR.

A temporary fix to get the station back on the air. The real repair work will begin when the antenna comes down to be inspected.

Update: The tower climbers did find a hole in the transmission line, just below the flange that connects to the antenna.  It looks like a pencil sized gash just before the line bends back to the tower.  Lightning? Rifle bullet?  Damage while installing?  We can’t really tell. They installed a patch over the hole which holds about 3 psi line pressure.  We then used a vacuum pump to evacuate the line, then recharged with dry nitrogen.

Regarding Pedro’s question below in the comments:  Since we found this problem quickly and were able to evacuate the line, there should not be any corrosion, that is our hope.  Time will tell

Orban Optimod 8000

A piece of vintage gear from the late 1970’s, the Optimod 8000 was and still is a good sounding box.  I have often thought that these processors would make an excellent internet audio processor using the test jacks on the back of the unit.  The audio on these jacks is unbalanced and has 75 µS pre emphasis.   It would be easy enough to make a de-emphasis network and create balanced audio with a 10K:600 ohm transformer.  Some experimentation may be required with the transformer primary impedance value.  Orban notes that not less then 1 MΩ impedance should be connected to the test jacks.  For the internet station looking to copy the “FM radio” sound, this unit would do the job nicely.

The 75 µS  de-emphasis network would look something like this:

75 microsecond de-emphasis network, unbalanced to balaneced audio conversion

75 microsecond de-emphasis network, unbalanced to balanced audio conversion

In this case, the values for the de-emphasis network are fairly critical, therefore 1% or better tolerances for the resistors and capacitors is required.

Even better, an LPFM or some other radio station on a budget could acquire one of these for relatively little on eBay or somewhere else.  With a little TLC, most of these units can be rebuilt and put back into service.  I would recommend that some type of limiter be used in front of it, such as a Texar Audio Prism or CRL SEP-800.

Some classical music stations prefer these units.  I have noticed that they have a nice,  mellow, open sound.  Not at all fatiguing and yet still offer a nice easy 10 dB gain reduction.  There is also a modification that can slow down the release time on the gain reduction.  More gain reduction, AKA compression, can be had with something else in front of the unit.

The best part about these units, there is no rebooting, no processor lock ups, software glitches or any of that non-sense.  Additionally, a quick look at the front of the unit shows very few user controls, making it almost impossible to screw up and sound bad. They are well built and so long as the electrolytic capacitors are changed out, fairly bullet proof.  Other processors, not so much.

Optimod 8000A under test

Optimod 8000A under test

This is an Optimod 8000A that I decided to put through its paces.

Really, how much more do you need?  I recorded this on the camera microphone using a replica table radio, seen near the end of the video on the right hand side of the frame.

I used the Technics SL-1200 MKII turntable through an ATI P100 turntable preamp into the Optimod.  The Optimod is feeding a BE FX-30 exciter running 15 watts into a dummy load.   The Optimod is running about 5-7 dB gain reduction, which is enough in my mind.  The BE FX-30 is still just about the best sounding analog exciter every made.

Rechipped Optimod 8000A, TL071 opamp

Rechipped Optimod 8000A, TL071 opamp

This unit has been re-capped and re-chipped at one point.  The re-chipping follows the Orban recommendation; the 4558 and 1556 opamps are replaced by TL071CP and TL072CP respectively, and the uA 709 and 301A opamps are left in the unit.  A good thing to remember, the uA709 and 301A opamps can be replaced by TLO71cP opamps in the event of failure.  The Texas Instruments TL0 series opamps are very good and readily available.

Optmod 8000A input and limiter board

Optmod 8000A input and limiter board

Overall, this unit is in good condition, however, like many such units, it is missing its brown “Optimod” cover, which goes over the input/output controls.

Manual is available at the Orban ftp site: ftp.orban.com.

Machinery as Art

I have always been fascinated with mechanical things. Moving parts; engines, motors, turbines, actuators, et cetera are all designed with function over form in mind. Still, there is a certain beauty to a well designed machine or piece of equipment.  Somebody had to design the equipment to fill a basic need.  In that design process, a certain amount of creativity was used to determine how it looks.  The title specifies machinery, however by extension, transmitters are included in this category.

Here are some pictures of various equipment and things found in a radio station:

Onan diesel generator

Onan diesel generator

Onan diesel generator, WROW-AM transmitter site, Albany, NY.

Overhead Conduit

Overhead Conduit

Overhead Conduit, WRKI transmitter site, Brookfield, CT

Borg transmitter

Borg transmitter

Playing around with photoshop. The back of a Nautel V 7.5 transmitter, WSPK transmitter site, Mount Beacon, NY.

Fire tower

Fire tower

Sixty foot tall Aeromotors LS40 fire tower, Clove Mountain, NY

Nautel NV

Nautel NV

Back of Nautel NV-40 transmitter, WVPS, Mount Mansfield, VT

LEA TVSS surge suppressor

LEA TVSS surge suppressor

LEA TVSS surge suppressor, WSPK, Mount Beacon, NY

RCA BTA1 transmitter

RCA BTA1 transmitter

RCA BTA1AR transmitter

Nautel V-40 transmitter

Nautel V-40 transmitter

Nautel V-40 transmitter (combined V-10 x 4), WHUD, Peekskill, NY

WHHZ studio console

WHHZ studio console

WHHZ studio console, Gainesville, FL

Chasing down a Pirate Radio station

I stumbled on this video on youtube. It seems like some old guy has too much time on his hands and is out being a private citizen vigilante:

Part one, he is driving around a neighborhood with a spectrum analyzer looking at signal strength:

Seems slightly creepy.

Then there is part II, the plot twist:

Actually, looks like a nice studio. PRE BMX II console, RE-20 microphones, and a live performance room at a radio station, what a concept.

Part III, trouble of a technical nature sets in:

Brave man, fear of heights is overcome because of his love of radio. I myself suffer from Phronemophobia, not in myself, but in other people.

So this series goes on for some, then… First, a Notice Of Unauthorized Operation (NOUO), then, A construction permit for a C1 station! Wow!

So, they are currently building out their station and putting up a tower. Check out 89.1 Ken’s FM-KNNZ and see how they are doing.  The call sign is KNNZ, licensed to Hawley, MN.  Real radio, alive and well in some places at least.

I wonder what kind of transmitter that is, I do not recognize it.

Good luck, guys.  I will have to check out the web stream, it sounds like fun.

Backing up the UPS

Power loss is a critical failure, thus much money is spent to prevent or mitigate commercial power interruptions in broadcast facilities.  Backup generators and Uninterruptible Power Supplies (UPS) are the first line of defense against commercial power interruptions.  It is prudent to research products and check reliability and interoperability when specifying and installing these systems.  However, even the best mechanical and electrical systems will fail, often at the worst possible time.  The UPS has a startling tendency to shut down, often at the worst possible moment, due to some internal control circuit or something similar.   This can happen when commercial power is being supplied without interruption.  The net result is some critical piece of equipment is now dark and the station is off the air.

Eaton Automatic Transfer Switch and UPS

Eaton Automatic Transfer Switch and UPS

There is a solution: The Eaton EATS EPDU TPC 2234-A Automatic Transfer Switch.

Eaton EATS EPDU

Eaton EATS EPDU

With this unit, the primary plug is connected to the output of the UPS, the secondary plug is connected to the commercial power source.  If the UPS fails, the load is automatically transferred to the commercial power.  Typically, the commercial power is also backup up with a generator.  The secondary plug can also be connected to a second UPS.  In theory, having two UPSs connected in parallel via an Automatic Transfer Switch would increase the Mean Time Between Failure (MTBF) by 50%.

UPS Eaton ATS EPDU block diagram

UPS Eaton ATS EPDU block diagram

The Eaton products come with a variety of options, including basic network monitoring, advanced network monitoring, switching and management.  Those features are available via Ethernet or serial data port.

Multiple layers of redundancy is the best method to avoid those late night, weekend or holiday phone calls.

WKZE transmitter site

We rebuilt this station’s studio couple of years ago.  WKZE is licensed to Salisbury, Connecticut.  The transmitter is located near Millerton, NY and the studio is in Red Hook, NY.  Today, I had to go to the transmitter site to fix a problem with the station’s processor.  While there, I snapped a few pictures:

WKZE, 98.1 MHz, Millerton, NY

WKZE, 98.1 MHz, tower near Millerton, NY

The WKZE single bay antenna is mounted on the left hand tower.

WKZE single bay Shively 6810 antenna

WKZE single bay Shively 6810 antenna with Radome

The transmitter is a CCA FM3000DS, made new in April, 1970:

WKZE 98.1 MHz CCA transmitter

WKZE 98.1 MHz CCA FM3000DS transmitter

The CCA designs are dirt simple. Grounded grid, driven with an external solid state amplifier that is a modification.

WKZE CCA transmitter, 42 years on

WKZE CCA FM3000DS  transmitter, 42 years on

WKZE CCA transmitter name plate

WKZE CCA transmitter name plate

As you can see, this transmitter was originally manufactured for WHVW-FM, which is now WCZX.  The station has a large, mostly cult following throughout the mid Hudson valley.  Even though it is a 3,000 watt class A station, it’s coverage carries far beyond it’s theoretical 60 dBu contour:

WKZE predicted 60 dBu contour

WKZE predicted 60 dBu contour

This is because the station is in mono.

The Polyphaser IS-PT50HN-B

I found this on the floor at an old transmitter site:

Polyphaser IS-PT50HN-B DC block surge suppressor

Polyphaser IS-PT50HN-B DC block surge suppressor

Since it appears to be discarded, I ignored the dire warnings and opened it up to look inside:

Polyphaser IS-PT50HN-B DC block surge suppressor

Polyphaser IS-PT50HN-B DC block surge suppressor

This is is a DC blocked lightning surge suppressor designed for 890-980 MHz, 750 watts maximum.  The two parallel wires represent a capacitor, coupling the radio to the antenna, the inductor acts as an RF block to the gas discharge tubes.  The design is such that the inductor acts to block the normal in use radio frequencies but will allow the 10-30 KHz lightning pulse to pass to the gas discharge tubes thence to ground.  The inductor and gas discharge tubes are on the antenna side of the unit.  I measured these units with a DVM and they all appear to be good.

My only comment on this unit is that there is no effort to maintain the transmission line impedance.  At the upper end of the UHF spectrum, this can lead to return loss and wasted power.  For a receive application, it may not be so bad, but for a transmitter, I would rather use something else.

For lower VHF frequencies, something like this can be DIY fabricated with minimal expense and effort.  The case must be bonded to the station ground.

FM Fool website

Just for geeks, the FM Fool website is.  None the less, it is a cool site to look at and can be used as a tool to find out what stations are available in any certain area.  Using the FCC database and terrain profile, it will print out a radar plot of all signals for any address in the US:

FM Fool Radar plot

FM Fool Radar plot

This plot is for my house based on a 30 foot outdoor antenna and includes all FM stations that are even marginally receivable.  We kind of live off to the side of nowhere.

The transmitter database was last updated on July 5, 2012.  Longer bars represent stronger signals.  Details about each transmitter are provided in the table to the right of the plot.

This is a companion site for the TV Fool website.  If you want to see what off air TV signals are available at any given location, this is the way to do it.  A few years ago, I was thinking of getting rid of the Cable TV in favor of off air reception.  Unfortunately, there are only a few off air TV channels available at my house.  Therefore,  I threw out the TV.  Problem solved.

 

We are experiencing technical dificulties, please stand by

There appears to be some issue with my version of WordPress, the server in use and the version of PHP. The ISP recently upgraded my sever and migrated my site over to a new unit, which was supposed to be transparent. Right. I am working with the ISP to resolve these issues as quickly as possible and return to my regular blogging.

In the mean time:

Update: All fixed, for now anyway. Something about a mismatched password in the backend. To all those that tried to comment, my apologies. It should all be working correctly now.

Maritime Radio Historical Society Night of Nights XIII

Every year on July 12, the Maritime Radio Historical Society (MRHS) commemorates the end of commercial Morse code use in the US. I have a soft spot for Maritime Radio, as that is where I began my radio career.  For nearly one hundred years, ship board radio operators, “sparks” communicated with land based stations using Morse keys and relatively simple low powered transmitters.  The skills gained by a good CW operator could only be attained by time spent sitting watch.

In order to remember those who did that service, several former coastal radio stations fire up transmitters once a year on July 12th.   This year’s frequencies are:

KPH KFS KSM WLO KLB Ship transmit
426 426 488
500 500 500 500
4247 4343 4184
6477.5 6274 6276
8642 8438.3 8658 8582.5 8368
12808.5 12695.5 12993 12992 12552
17016.8 17026 16968.5 16736
22477 22280.5

Festivities begin at 8pm eastern time.  In addition to those frequencies, K6KPH will be on the air on 3550, 7050 14050 and 21050 KHz.

KPH, KFS and KSM are all operated from Point Reyes National Park, transmitters are on Bolinas. This is a video of the transmitter gallery in Bolinas:

Other video of Bolinas Facility:

Former KPH receiver site, Point Reyes National Park:

This is a former coastal station site in Cape Cod, which was torn down:

Lots more information at the Maritime Radio Historical Society site.

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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