October 2017
M T W T F S S
« Jul    
 1
2345678
9101112131415
16171819202122
23242526272829
3031  

Archives

Categories

The Gates Air FAX-10, Numero Dos

This is the second Gates Air FAX-10 that I have installed. This one is in the shipping container transmitter site from the previous post of the same name.  In this case, we dispensed with the equipment rack that came with the transmitter and installed it in a standard Middle Atlantic rack.   The Harris rack configuration wastes a lot of space and since space is at a premium, we decided to do it our own way.

Gates Air FAX-10 in Middle Atlantic rack

Gates Air FAX-10 in Middle Atlantic rack

The bottom of the rack has the transmission line dehydrator. The top of the rack has the Dielectric A60000 series 1 5/8 inch coax switch, a Tunwall TRC-1 switch controller and the Burk ARC-16 remote control.  I cut the rack panel top to accommodate the coax switch.  The racks were removed from an old studio site several years ago and were in storage since that time.

Gates Air FAX-10

Gates Air FAX-10

The Gates Air FAX-10 transmitter on the air, running a sports-talk format.

Dummy load and Broadcast Electronics FM10B transmitter

Dummy load and Broadcast Electronics FM10B transmitter

View from the other side showing the test load and BE FM10-B transmitter.  This transmitter had a problem that I have run into before with BE FM transmitters.  The jumper between the exciter and IPA had the wrong phase rotation causing reflected power.  I added a foot to it’s length and that problem disappeared.

North Adams Tower update II

Work continues on rebuilding the North Adams tower after the collapse of March 2014.  Over last winter, a new tower was erected.  This is a fairly substantial tower.

New North Adams tower on ground

New North Adams tower on ground

North Adams new tower erected

North Adams new tower erected

In the interim, a new Shively 6810 four bay half wave spaced antenna was ordered. This antenna will be combined for two stations, WUPE-FM and WNNI using a Shively 2630-2-06 branched combiner. The 70 foot utility pole next to the building will be retained as backup facility for both stations. The Shively Antenna went up in stages.

New WUPE-FM and WNNI Shively 6810 antenna

New WUPE-FM and WNNI Shively 6810 antenna

Tower climbers rigging tower for new antenna

Tower climbers rigging tower for new antenna

Prescott Tower from Rutland Vermont was on site to do the tower work. They were the primary contractor for installing the new tower and did a really nice job of it.

New North Adams tower ice bridges to various shelters

New North Adams tower ice bridges to various shelters

Hanging the top two bays of new antenna

Hanging the top two bays of new antenna

Lift of bottom two bays and first tuning section

Lift of bottom two bays and first tuning section

Securing bottom section and bolting bays together

Securing bottom section and bolting bays together

After that, there was twenty feet of rigid line, another tuning section, then the 1 5/8 inch helax into the transmitter room. The antenna was tuned and the load looks very good. We are waiting for the electrician to finish wiring up the new racks and we will move both stations into their new home.

Installation Check Lists

On the subject of project management; often times, we need to keep track of the small details that can derail a project, blow the budget and upset schedules. A quick check list can help to identify things that might not have been planned for. I developed a checklist mentality in the military. There, we had checklists for everything. Simple day to day things like disposing of garbage over the side, or pumping the CHT (sewage) tank to complex evolutions like entering or leaving port all had a checklist.  On the aforementioned CHT tank; the Coast Guard cutter I was on had a vacuum flush system to conserve water.  Emptying the CHT tank involved a complex set of valve openings and closings to rout compressed air into the vacuum tank and literally blow the sewage overboard.  Anyone can see the danger in such a design.  Failure to follow the exact procedure resulted in raw sewage blowing out of the nearest toilets, which were unfortunately (or perhaps humorously) in the lower level officer’s staterooms.

But I digress.

I have made a series of outlines for different project types.  These can be used as general guidelines for project planning and management.  Of course, each project is different, but these are flexible enough that they can be adapted on a project by project basis.

These are for general use, and should be adapted for your own purposes.  Don’t forget to document and label all the wire runs, etc.

Also, do not forget the transmitter site maintenance checklists: FM transmitter site maintenance list, AM transmitter site maintenance list. I have used these reliably at many different sites since I committed them to writing in late 1999.

Copper Thieves

If you are the type of person that drives around to transmitter sites and steals things; fuck you. You have no idea the problems you are causing to get a few extra dollars worth of scrap copper.

Missing copper ground buss bar

Missing copper ground buss bar

I have a feeling that most of these copper thefts can be attributed to out of town tower contractors removing old cellular equipment from towers.  Notice, only the buss bar and copper ground wire is missing.  They did not try to cut the transmission lines.  In other words, they seemed to know what they were doing.  I have noticed around here that a when a particular contractor, employed by an unnamed large company that rhymes with glint, would work at a site, things would be missing afterwards.

Perhaps it is just a coincidence. I have never been able to catch anyone pinching things. However, if this is you, and I catch you, you can rest assured that I will block you in with my car, then walk down the road and call the police.

The Shively 6710 Antenna

Shively 6710-1 FM antenna

Shively 6710-1 FM antenna

Perhaps that is one Shively Antenna that you haven’t heard of. They were an odd-ball combination of a horizontally polarized antenna with an adjustable vertical element. This design allowed the station to adjust the ratio of horizontal to vertical power from a range of 1:1 to about 4:1 (H:V).  Why would this be a desirable feature?

Back in the early days of FM broadcasting, almost all stations had horizontally polarized antennas.  This system worked remarkably well, stations could broadcast at moderate power levels over fairly long, line of sight (or mostly line of sight) paths.  Most FM receivers were stationary units installed in people’s homes often with outdoor antennas.

It was not until the late 1960’s and early 1970’s that FM radio receivers became a stock option in most low and mid cost automobiles.  It was then that a slight problem with FM broadcasting was discovered;  car antennas are vertically polarized.  People driving around in their new machines found that the FM reception was not all that great.  Stations began adding a vertical component to their signal to help improve the mobile reception situation.

I found this Shively Brochure in a file cabinet drawer at the WFLY transmitter site.  This model antenna was ordered and installed by that station in 1970.  It had a 3:1 horizontal to vertical ratio.  Why not install a fully circularly polarized antenna?  Because often that necessitated installing a new, more powerful transmitter.   Every watt of power taken from the horizontal plane and added to the vertical plane reduced the ERP by that much and had to be made up with more transmitter power output.  Often times, the ratio of H:V power would be adjusted to take up whatever headroom there was in the transmitter and the station would run that way until the next transmitter replacement cycle.

I found the remains of this antenna in the woods, north east of the tower.

Shively 6710 antenna section

Shively 6710 antenna section

This section looks pretty well destroyed.  It is probably better to dispose of these type things by scraping, rather than dumping them in the woods.  While there is not a lot of scrap value to this unit, it can become an attractive nuisance copper thieves and other vandals if it is left laying about.

It is a strange looking piece of kit, a sort of make do until the situation could be fully rectified.  I think this antenna was in service until 1986 or 87 when it was replaced with a circularly polarized ERI.

Filing an STA

FCC rules stipulate that when a station is operating at a variance from its licensed parameters for more than 10 days, Special Temporary Authority (STA) is required.  The reasons for requesting an STA are varied but could include things like:

  • Damaged transmission equipment
  • Loss of transmitter site or building use
  • Loss of tower
  • Eviction
  • Facilities upgrade or renovation
  • Natural disaster

The loss of transmission tower at WUPE-FM falls into one of those broad categories.  Thus, we have filed a STA with the FCC for temporary transmission facilities while a new tower is being constructed.  Since the old tower is completely lost, we specified a new tower location, new height above average terrain (HAAT), new ERP and environmental certification.  To gather that information, several steps were needed:

  • Obtain new tower location.  This was done with a GPS receiver and verified on itouchmap.com.  Once the NAD83 position was obtained, it needed to be converted to NAD27 for the FCC filing.  The FCC has a conversion tool on their website.
  • HAAT calculation is fairly simple, use the HAAT calculator tool on the FCC website.  For this, the antenna radiation center height Above Mean Sea Level (AMSL) is needed.  Using a topographical map, find the ground level AMSL, convert it to meters, then add the radiation center height above ground level (AGL).
  • The Effective Radiated Power (ERP) calculation is also simple; Transmitter Power Output (TPO) minus system losses (transmission line and antenna gain). It is easiest to do this in dBm, e.g. convert the TPO from Watts to dBm, then add or subtract the gain or losses in dB, convert the final product back to Watts.
  • The environmental statement is slightly more tricky.  Basically, the filer is certifying that the STA complies with all environmental regulations including OET-65 (RF exposure limits).  Since the temporary antenna is significantly lower than the original, some investigation is required.  For this, there are two methods to demonstrate compliance; ground measurements with a NARDA meter, or RFR worksheets which are a part of the broadcast station renewal form, FCC-303s.

I have taken the RF worksheet sections out of the 303s and separated them into the FM RF Worksheet and the AM RF Worksheet.  These worksheets are not effective for large tower farm type sites where there are too many variables and RF contributors to be accounted for.  The calculations on the worksheets are not conclusive, however, if the facility in question falls under the limits, it is generally accepted as being in compliance.   Taking ground measurements with a NARDA meter is the definitive method for determining RFR compliance.  Since this is a relatively simple site, the worksheet calculations should be sufficient.

The worksheet calculations show that the RFR is with in both the controlled occupations limits and the uncontrolled general population limits.

WUPE-FM temporary antenna RFR worksheet

WUPE-FM temporary antenna RFR worksheet

The position of the new temporary pole verified on itouchmap.com:

itouch_nadams

It is never good to be operating at a varience from licensed parameters without notification of the FCC. Such things could lead to fine or other problems for the broadcaster.

WMHT’s former analog transmitter

During the digital TV conversion in the US, all broadcast television stations installed new transmitting equipment and antennas.  Most stations ended up on a different frequency than their original analog channel.  In Albany, New York, all of the TV stations moved to a common transmitter site and installed their antennas on a single tower.

home of WRGB, WTEN, WNYT, WXXA, WMHT, and WCWN

Albany DTV tower, home of WRGB, WTEN, WNYT, WXXA, WMHT, and WCWN

For more on the Albany DTV site, check out the NECRAT page: www.necrat.us/albdtv.html

So, what happened to the old Analog TV sites in Albany?

For the most part, after the analog turn off on June 12, 2009, the sites have sat empty.  Such is the case with the former WMHT site.

Sign outside of former WMHT transmitter building

Sign outside of former WMHT transmitter building

This old sign about sums up the end of analog television.

Former WMHT Comark analog transmitter

Former WMHT Comark analog transmitter

Former WMHT analog transmitter wide shot

Former WMHT analog transmitter wide shot

Former WMHT operator position

Former WMHT operator position

The former transmitter operator desk. Maintenance log is still open. From the looks of things, they opened the circuit breakers and walked away. Everything remains intact from the antenna to the klystrons and exciters. It does appear that the coolant has been drained from the system. Other than that, it seems like the whole thing could be restarted with minimal effort.

Former WMHT Onan DFN 350 backup generator

Former WMHT Onan DFN 350 backup generator

There were two Onan DFN 350 backup generators. With a TV transmitters, it is vitally important to run the cooling system after shutdown. The idea here is that both generators in parallel could run the whole station, if one generator failed, then the cooling system would still run and cool the klystrons.

Former WMHT site kitchen

Former WMHT site kitchen

Former WMHT tower, wave guide and WVCR antenna

Former WMHT tower, wave guide and WVCR antenna

The former WMHT tower, which currently holds the WVCR-FM, WXL-34 (NOAA weather radio), and W44CT-D (Three Angles Broadcasting) Low power TV transmitter.

Current site occupants; WVCR-FM and W44CT-D

Current site occupants; WVCR-FM and W44CT-D

These equipment racks and the NOAA weather radio transmitter in the other room are the only active equipment at this site.

WMHT-TV Chanel 17 (488-494 MHz) signed on 1962 from this site.  The Comark transmitter was installed in 1984.  The station’s analog ERP was 2000 KW visual, 200 KW aural.

It is an interesting site.

Decomissioning a NEXTEL site

Remember when “NEXTEL (b-b-b-beep), how business gets done…” Well, not anymore. NEXTEL was purchased by Sprint in 2005 and their product lines were combined.  Thus, all of these old NEXTEL sites have become redundant and switched off.  This particular site was co-located with one of our FM radio clients, which required a power reduction while the old equipment was removed from the tower.  I took the time to grab a few pictures of the process:

Former NEXTEL communications equipment room

Former NEXTEL communications equipment room

All of the equipment was removed from the equipment shelter. This site has been switched off since June of 2013 and everything in it is destined for the scrap yard.  This equipment worked on the 800 MHz band, which has been re-purposed for Public Safety and Critical Infrastructure, e.g. government users.  These racks and radios look like they were expensive:

NEXTEL equipment racks and radios

NEXTEL equipment racks and radios

Speaking of expensive, this site had over 4,500 feet (1,370 meters) of 1 5/8 inch foam coax, which was cut up and scrapped.  At today’s prices, that cost $13.25 per foot.

Scrapped transmission line

Scrapped transmission line

The tower was rigged:

Rigging tower to remove antennas

Rigging tower to remove antennas

Each of the three panel sector mounts were removed and lowered to the ground.

Dropping cellular panel antennas

Dropping cellular panel antennas

The NEXTEL antennas were mounted at the 260 foot (80 meter) level of a 395 foot (120 meter) tower. It took some time to remove all of the antennas and equipment from the tower.

Cellular panel antenna array being removed from a tower

Cellular panel antenna array being removed from a tower

I looked on the Sprint website and could not determine if they still offer a push to talk service option (direct talk).  With all of the communications options available today, I do not expect there would be much call for it.

For old times sake, here is an old NEXTEL commercial from many years ago:

They did have a good marketing department…

The PIROD PRLC-A tower lighting controller

PIROD tower company has been around for a while, thus there are likely many of these tower light controllers out in the field.  They perform a vital service in controlling and monitoring tower lights at remote transmitter sites maintaining a safe operating environment for aircraft and compliance with FCC rules.

PIROD was sold to Valmont in 2004, Valmont no longer manufactures or supports the product.  All is not lost, however, as XCEL Tower Controls does support it and parts are still available through them.

These units were fairly rugged, had good surge suppression on the incoming AC lines and are designed for easy access to service parts.

PIROD PRLCA tower light controller, WRKI Brookfield, CT

PIROD PRLCA tower light controller, WRKI Brookfield, CT

This particular controller is being installed at WRKI in Brookfield, CT.  We are adding toroid cores to the tower lighting circuits coming off of the tower because the last controller has been mostly destroyed by lightning.  It is a tall tower, on top of a tall hill, thus it gets struck by lightning many times over the course of a year.

WRKI tower, Brookfield, CT

WRKI tower, Brookfield, CT

The block diagram looks like this:

PIROD PRLCA block diagram

PIROD PRLCA block diagram

Click for higher resolution.

The basic schematic looks like this:

PRCLA tower light controller schematic

PRCLA tower light controller schematic

Click for higher resolution.

The entire manual can be found here, (medium sized .pdf) courtesy of John Brickley of EXEL tower controllers.

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!