We have been poking away at this one for the last year or so. It seems that the previous owners of Berkshire Broadcasting had filed for a translator to rebroadcast WNMB, (100.1 WUPE-FM) North Adams in downtown Pittsfield, during the great translator rush of 2003. When the CP showed up in the mail last March, the current owners were quite surprised.
After looking at the Construction Permit, we made some modifications;
- Moved the transmitter location from 100 North Street to 1 West Street (Crowne Plaza Hotel) which is the tallest building in Pittsfield. Antenna AGL is 44 meters (145 feet).
- Changed the rebroadcasting station from WUPE-FM, North Adams to WUPE-AM Pittsfield
- Changed the antenna to non-directional
- Changed the ERP from 48 watts to 100 watts
We were able to make those antenna and power changes because we changed the parent station to the local AM station, WUPE, 1,110 KHz. The previous power/pattern was submitted to keep the translator signal within the 60 dBu contour of the FM station in North Adams.
This, I feel, is the best use for an AM to FM translator. WUPE-AM is a class D station with no night time service. Adding a night time service greatly increases the station’s value to the community. While the 100 Watt translator does not cover near as much as the 5,000 watt AM station, the transmitter location is right in the center of Pittsfield, so coverage of the population center is excellent.
The view from the top of the Crowne Plaza is quite spectacular. I am pretty sure I will have a lot of transmitter maintenance to do right about the middle of October.
W277CJ 60 dBu contour
The installation is fairly straight forward:
W277CJ installation, roof of Crowne Plaza, Pittsfield, MA
W277CJ transmitter in outdoor enclosure
The outdoor enclosure is a DDB POD-16DXC which is rather nice, it comes with rack rails and a thermostatic controlled fan.
W277CJ Shively 6812B antenna
The antenna is a Shively 6812B with RADOMES. The transmitter is a BW Broadcast TX600v2. I really like these transmitters, they are well designed and rugged. We have yet to have a single failure of one of these units in the field.
The station ERP is 100 watts, so a small bit of calculating is required to arrive at the proper station TPO. I find it easier to make all these calculations in the decibels per milliwatt (dBm) unit domain, then convert back to watts. Thus, the ERP is 100 watts, or 50 dBm. The antenna has a gain of -3.4 dBm. We used 25 feet of LMR-400, which at 103.3 MHz, has a loss of -0.26 dBm. The total losses are -3.66 dBm, making the necessary TPO 53.66 dBm, 232.27 watts or rounding down to 232 watts.
That is how long it has been since I started this blog. Six years and 727 posts later, I find myself wondering how much longer I can continue this. I have not been posting too much lately because I seem to have run out of things to say. Posting just for the sake of posting seems to dilute the good material with mediocre stuff that has to be deleted later.
The radio business has changed little in the last six years; fewer owners, AM is still plagued with technical issues and poor programming, the FM band is getting jam packed with translators and the occasional LPFM, HD Radio is, well HD Radio.
My situation changed as well with the change in jobs, a new degree, more family responsibilities, etc.
I was thinking about ways to make this more interesting and perhaps doing more with my under utilized youtube channel would be fun. I was called an “old timer” a few months ago as a compliment and I am not sure how I feel about that. After a bit of reflection, I realize there is some truth to it and there are fewer and fewer of us out there that can do what we do. Perhaps some informational things on how to trouble shoot and find problems, what a day in the life of a radio engineer is actually like, radio station people, etc. I know that good trouble shooting is an art form.
I would need a tripod and a better camera.
In the mean time, here are a few statistics from the last six years:
- I have typed a total of 812 posts, of which 727 are public and there are about 30 drafts on various subjects hanging out, waiting to be finished and posted. Out date material is usually deleted when I get around to it.
- The blog has a decent following, with an average of 700 page views a day, approximately 120 regular readers and 185 RSS subscribers.
- There are 3,494 comments and the spam filter has eliminate 1,102,631 useless, fake, ridiculous or otherwise stupid machine generated garbage.
- There is also an international readership, with approximately 40% of visitors coming from outside of the US. According to my flag counter, these are the countries that have not visited yet:
- British Indian Ocean Territory
- Central African Republic
- Christmas Island
- Norfolk Island
- North Korea
- Saint Barthelemy
Everyone else has made at least one appearance. I am a little bit disappointed that no one from North Korea has graced our presence.
- Top six non-US countries are Canada, UK, India, China, Germany and France.
- There are approximately 1,380 images of various interesting things. Most of them are my own, some are borrowed from other sites or the public domain.
I hope that I can continue this thing in some way or format. I have certainly enjoyed meeting many people, reading comments, replies, off line emails and such. It has been an overall positive experience and I value everyone’s input.
I found these old drawings in the filing cabinet and thought they were kind of cool. They look like they were drawn sometime in the 50’s for the WPTR studio at 1860 Central Avenue in the Town of Colonie.
It looks like there was a lot of Neon, including a speller, which I take to mean the sign would spell “W-P-T-R 1540″ then turn off again.
This was the sign for the entrance to the studio building
WPTR sign for front of old studio building at 1860 Central Avenue
I think this is a take off on the old KHJ sign in Los Angeles.
There is some disagreement in the organization that I work with regarding the use of Shielded Cat 5e cable. Is it needed and if so, when and where? Category cables commonly used in Ethernet computer networks and also used for analog audio and other data applications come in a variety of flavors. Shielded (Shielded Twisted Pair or STP) and unshielded (Unshielded Twisted Pair or UTP) Cat 5, 5e and 6 are the most common in radio broadcast facilities.
The main purpose for using UTP and STP for high speed data transmission is common-mode rejection. Cables that are installed in office buildings are subject to various electric and electronic noise sources. Properly installed UTP works to reject these unwanted signals by using differential signaling, which is balanced. Differential signaling can best be described as transmitting information using two complimentary signals that are opposite from one and other.
Noise rejection, differential signaling. “DiffSignaling” by Linear77 – Own work. Licensed under CC BY 3.0 via Wikimedia
The key performance measurement in category cable is Common Mode rejection. Outside noise will introduce a common mode signal on the cable which will be cancelled out by the differential amplifier on the receiving end of the circuit. Proper terminations and good wiring techniques are very important for proper performance.
Using the correct patch panel termination, terminating block or RJ-45 (8P8C) connectors are required to maintain the advertized bandwidth of the cable. There is also a difference in connector and terminating block designs for solid versus stranded cables. Using improper connectors for the type of cable installed can cause dropouts and loss of data.
When installing category cable, care must be taken not to kink the cable, not to exceed the recommended minimum bending radius or exceed the maximum pulling force. Each of these will degrade the cable performance by changing the physical characteristics of the cable. Each pair of wires in category cable has a different twist. Altering these twist ratios by stretching the cable or bending it too sharply will increase the NEXT (Near End Cross Talk) and FEXT (far end cross talk) between pairs. In Gigabit networks, this will degrade throughput and create bottlenecks.
Generally speaking, the minimum bending radius is four times the cable diameter, or approximately one inch for Category 6 cable. The maximum pulling tension is not more than 25 ft/lbs or 110 Newtons.
Category 6, Shielded Twisted Pair
In high EMF environments, shielded cable (STP) can be beneficial in mitigating high electrical noise along with proper installations techniques noted above. Signaling levels on 100BaseT are +1, 0 and -1 volt (MLT-3 Encoding). On Gigabit Ethernet, the levels are +1, +0.5, 0, −0.5 and −1 Volt (PAM-5 Encoding). Induced voltages on in cables from external sources can degrade network performance and create bottlenecks. High EMF environments would include places like transmitter sites and anything on a tower or rooftop. Properly terminated shielded cable is necessary for EMP protection from lightning strikes or other sources. STP has special shielded metal connectors which each category cable class. These connectors supply the path to ground through the RJ-45 jack.
Ungrounded shields are useless.
RJ-45 or 8P8C shielded plug for Category 6 STP
There are also other cable characteristics to consider such as UV resistant jacking for outdoor installations or gel filled (AKA “flooded”) cable for wet locations. Fortunately, there are plenty of sources for these types of cables and they are not terribly expensive.
To answer the question at the beginning of the post; STP can be beneficial at high EMI/EMF or RF sites to mitigate induced voltages on the cable from external sources provided it is properly terminated. In office and studio locations which are not at or next to a transmitter site, UTP is more than adequate provided it is properly installed and terminated.
So, I was working at one of our FM clients in Albany when I decided I had a few moments of spare time, I could neaten up the remote control rack. I opened the rack door and was staring intently at the remote control interface panel, when out of the corner of my eye, I saw something move.
Now, the top of the rack is a little bit dark and I was not sure what I was looking at. At first I though somebody had stuffed a rag in the top of the rack. But, I could not figure out why anyone would do such a thing. Then I thought it was some cardboard. I almost reached up and grabbed it, but something was amiss. Then I saw the tough flick out and smell the air:
Transmitter room denizen
At this point, I think I may have said something like “Oh, shit!” and took several steps back. Those colors and pattern have two possibilities; Copperhead or Grey ratsnake. Since I could not really get a good look at its head, I could not tell which it was. I went and got a work light to see better with.
Grey rat snake
A copperhead is a pit viper, which has a triangular shaped head and a small indentation or pit under each eye. This snake has neither, so it is fairly harmless. Actually, the ratsnakes are beneficial because they eat the mice and other pests around the transmitter building. There are several versions of these in the northeast, including a black ratsnake which happens to look just like a piece of 7/8 coax laying across the pathway to the door, until it moves that is…
This species can get to be about 6 feet long (1.8 meters) and the larger ones can draw blood when they bite. Even though he looked to be on the small side (approximately 30 inches or 76 cm), I decided that discretion is the better part of valor, closed the door on the rack and did something else for a while.
This post has nothing to do with radio engineering, but is full of geeky goodness, nonetheless. My son is playing Little League again this year. This is his first year in the majors division, and I have to say, I have been thoroughly enjoying watching his games. There is, of course, one minor glitch in the matrix; the scoreboard, which occasionally looks like this:
Little League Scoreboard, missing LED segments.
Now, that is more of an annoyance than anything else. I know what inning it is and what the score is. Truth be told, most of the time the scoreboard is being run by one of the parents (read: a mom) and they can become distracted at times. Very often, the ball/strike/out count is not correct, which in turn causes the home plate umpire to angrily stare up and the scorekeeper’s window.
As I was saying, more of an annoyance…
Regardless, I thought to myself; jeez, I fix things, perhaps I should have a go at that sign. So I spoke to one of the Little League board members who was more than grateful for any assistance I could render.
Thus, one afternoon, after work, I got the ladder out and started poking around to see what I could learn. These signs are relatively simple. Each digit on the sign has one circuit board. Each circuit board has seven segments. Each segment has fourteen LEDs in series. There is a Toshiba ULN2803APG, which is a 16 pin darlington driver, a LM 317 voltage regulator which is fixed with a 62 ohm resistor.
Scoreboard single digit circuit board
Approximate schematic scoreboard circuit board segment
After poking around with the DVM for a while, I determined that the bad segments were due to open LEDs. I measured the working LED’s and determined that each LED was dropping about 1.7 volts. I took a board home with me and rummaged around in the parts bin until I found some orange 5MM LEDs that matched the voltage drop of the ones on the board. I confirmed my ladder top troubleshooting findings on the work bench using the DVM in diode mode. I also noticed that the Fluke DVM had enough current to light the LED, thus making troubleshooting much easier. There were three bad circuit boards with various segments out.
Scoreboard LED voltage drop
Scoreboard individual LED testing good
A few minutes with the soldering iron and presto:
Sign repaired. I little further research and I found that an Everlight MV8104 LED (Mouser part number 638-MV8104) is a near perfect replacement. Literally, a 23.3 cent (US) part.
In all fairness to the company that makes the scoreboard, this unit was new in 2003 or 2004. It has spent at least 11 years outside in upstate NY, which is not a tender climate. They will replace the digit circuit boards for 175.00 each, plus $25.00 shipping. My repair work used 9 LEDs ($2.10) plus about two hours troubleshooting and repairing vs. $600.00 plus perhaps an hour to replace the boards.
After one of our clients had an FM station go off the air over the weekend, I investigated and found this:
Transformer melt down
Looks like something one might find in the reactor room at Chernobyl or Fukushima.
Transformer melted down
This is at one of those sites with three phase open delta power. Needless to say, the transformer is toast, perhaps the entire transmitter too. This will be another fun transmitter scrapping project. I was thinking about this; over the last five years, I have scrapped at least ten to fifteen old tube transmitters. The old tube types are going away fast, as are those that can still work on them.
Photoshop, oh photoshop:
For some reason, I found this funny. I think the dad jokes are rubbing off on me.
This is a tower behind one of our FM transmitter sites. In the past, it has housed paging and two-way services. It has always been sort of a slum, in my opinion. Several times, malfunctioning or improperly installed 900 MHz paging radios from this site have caused interference with our 950 MHz STL receivers. In recent years, all those things have gone away however, to be replaced by a Wireless Internet Service Provider (WISP). Even with this change, the site is mostly overgrown and uncared for.
Yesterday, I noticed the tower was not as tall as it used to be, so I walked down the hill and saw this:
Self supporting tower after loosing top section
It appears this happened a few weeks ago. View from the other side:
Self supporting tower section resting on roof of building
Close up of tower section that failed:
Looks like the bolts that held one the flanges together failed, the tower was pushed over by a strong NE wind causing the other two legs to fail. Truth be told, the tower had been in rough shape since the mid 90’s. I am surprised that it stayed up this long.
WISP sector antennas. I don’t know if they owned the tower or were tenants. Either way, this is going to cost a few rubles to repair.
Looks like the shelter took a little bit of damage too. To be honest with you, I hope that this is it for this site. I would be nice if they take down the stump, scrap the lot of it and move somewhere else.
The original V series Nautel transmitters have required a couple of firmware upgrades in some cases.
Upgrading the PA module firmware on Nautel V-5D transmitter, WDVT, Rutland, VT
The first was for the controller to add a little bit of bias to the PAs during analog operation. The second one I have had to do is to the PA modules themselves which was to keep the power supplies from shutting off during re-transfer from Generator power to commercial power.
I have done several of these and once you get the hang of it, it only takes a few minutes to complete. Still, I remember when transmitters didn’t have firmware. The low voltage control circuits were either 120 or 240 VAC with big relays and contactors that loudly confirmed their closure before any meters began to move.
Regarding Nautel transmitters in general; the newer models are not same rugged, reliable designs that were common in the past. We have AM ND series transmitters that have been on the air for 20 years without a single failure. The models rolling out of the factory these days often have switching power supplies fail without reason or warning and RF pallets that are fragile things. Ah well, I suppose all things are cyclical.