Most Popular Articles
Simple solutions for a stress-free system
Photo courtesy of Richland Towers Inc.
A robust transmission system is one that provides superior signal and audio quality, and provides this superior product even in adverse conditions. The system should also be fault-tolerant, and easy and inexpensive to maintain. Furthermore, remotely located systems should provide accurate and timely information about site conditions to remote users and maintenance personnel so that decisions can be made quickly in emergency situations.
All of these concerns must be addressed in each phase of a project - design, construction and maintenance.
The design phase
Because engineers are usually asked for their input, it is incumbent on the engineer to make his client or employer aware of the relevant issues and their relative weight, so that the client can make good decisions. There are times when the engineer may feel as though he is saving his clients from themselves — and there are times when that is true — but remember that management counts on the engineer to know the issues. Pounding the table once in a while to get a point across is OK; after all, a few bruised egos are better than being stuck with a bad site — but be careful not to sneer at non-technical types. Don't let an ego get in the way, either. I've been too pushy on projects before, and I have gotten myself fired more than once, too. In the end, the client got a bad facility because he hired an easy-to-get-along-with engineer, and I lost the money and the satisfaction of finishing the job after I had laid all the groundwork. This was a lose-lose situation for sure.
The chosen transmitter site should provide adequate coverage of the desired signal area, which may not necessarily be the city of license.
The chosen site should provide good coverage of the desired area, which is not always the city of license. The character of the land should be considered with height of terrain being of the greatest interest for an FM station and low, flat land with good conductivity being paramount for an AM station. Use the station's consultant if possible. A good consultant is well acquainted with site selection criteria, and he may have a few tricks, too. He can earn his pay in avoided pitfalls due to his advice.
Remote land is often chosen for transmitter sites due to low acquisition costs, but keep in mind that access roads to remote sites are expensive to clear and maintain, and management may balk at the continuing costs. Another potential problem with remote sites is the quality and availability of commercial ac power. In rural areas, the power company may be unwilling to provide three-phase power (or any power) without high up-front costs, and the station may find itself on the end of a long and unreliable power line with poor regulation, large numbers of surges and poor power-failure response times. Any assessment of a potential site should include input from the local power company and also from other stations in the area or other nearby customers — even residential ones. This is also true for telephone and any other utilities that may be desired at the site. Projects can be delayed at the last minute because management foolishly assumed that anything they needed could be provided in short order by the utility companies. Sometimes utility or access road issues can swing the tide in favor of a more expensive but more accessible site. Because this is one of the first decisions made for any facility, be sure to obtain the pertinent facts early in the project.
Make sure that your client or employer knows the issues regarding tower height vs. coverage area vs. price, and number of FM bays vs. coax cable and transmitter size. If an ill-advised decision is made, speak up. I recently had a client decide to diplex a low-band AM station at a higher-frequency AM site with a short tower — too short for that low-band signal. I advised him so, but the client went ahead anyway. The FCC refused the application, citing the short tower height. Now the station owner is building a taller tower, and I believe that this will serve the low-band station better.
While remote land may offer an attractive acquisition cost, adding commercial power and access roads may counteract the savings.
Simple but true: Buy good equipment. Of course, it gets complicated in a hurry when faced with choosing between a major manufacturer or a less expensive manufacturer, installing an auxiliary transmitter, STL, antenna, processing, dial-up or dedicated remote control, a coax switch or a dummy load. It's better to have one set of first-class equipment than two sets of substandard equipment.
Budget the essential items first, such as surge protectors, proper tower and building ground systems, generators and radomes. All too often stations try to cut budget corners by forgoing these infrastructure items because they are all but invisible; they add no capabilities and therefore have no champions, no constituencies. If a station doesn't budget for them now, it will have a hard time getting them budgeted later, and then only after the station is crippled and someone may have to take responsibility. Nobody ever wants to hear “I told you so.” Do everything possible to fight for these orphan (but essential) items now. Most managers know how hard it is when choosing what to cut from the budget, and they are usually aware of the bad (if delayed) consequences of their actions.
If you can't afford new equipment, consider used equipment. Late-model, good-quality used equipment will almost never turn out to be a lemon, and an engineer can probably save enough money to put some of the extras he thought he was going to have to do without back into the budget.
The more inaccessible the site, the better the remote control should be. This applies to all backup equipment. For a truly remote site, the remote control should have complete control over all transmitters and should monitor everything in sight: full transmitter metering/status including internal overloads shown separately from VSWR; extensive site monitoring with ac power including phase loss, site and outside air temperature, site intrusion and security, full tower light monitoring and STL signal loss and generator monitoring.
A backup power generator is an essential item at a transmitter site, particularly in remote locations.
No matter how good the equipment is or how carefully the site is selected, the radio transmission system won't be robust if the building itself is falling down. Buildings that are too small don't work well either. Make sure that the building is built well for its location and is big enough to accommodate present equipment needs with enough room for reasonable expansion. Think about concerns such as ceiling height and required RF plumbing before you are forced to put equipment such as coax switches where they hit you in the head every time you walk past.
The construction phase
This is where all the decisions from the design phase are implemented. It falls on the project engineer's shoulders to make sure that the subcontractors install the subsystems in accordance with the design. Be assertive. An engineer only has to make one subcontractor redo work for word to get around that he is to be taken seriously. Make sure that management backs you up — this is important.
If the project engineer is not going to climb the tower to check their work, use a tower company. Even then, check everything possible from the ground. Make sure that they properly handle items that are small to them, and therefore often easily overlooked, such as grounding kits or tower lighting conduit weep holes. If the subcontractor gets the idea that shoddy work and cut corners won't be tolerated, he is more likely to expect that standard for all the work at the site.
Don't let any subcontractor off the site without double-checking his work. Make sure that everyone knows that they may be called back if problems develop. If possible, arrange for some percentage of their payment to be withheld until the station is on the air and everything has been observed to run properly for some period of time (10 percent for 10 days, for example). This gives them a clear incentive to make sure that the station is happy as a customer.
A clean and organized transmitter site makes a more efficient work environment, particularly during emergency maintenance.
Arrange for work, such as grounding or wiring in the slab or walls, to be inspected before it is covered. Don't rely on city or county inspectors for this because it isn't their site. Don't forget small items such as fence placement and FCC-required signage.
No matter how well designed or built, a facility has to be properly maintained or it falls apart.
Fighting persistent failures that consume all of the engineer's time and parts budget is not efficient. Lack of good surge protection or grounding, poor-quality or worn-out equipment, or equipment poorly sized for the job are the usual culprits. These issues have to be addressed, and quickly once an engineer is put in charge of a particular site, or else management will lose faith in his ability to solve the problems. If the failures are obvious enough and often enough, then the engineer should not have much trouble making a case to management of proper remedial action. This clearly takes precedence over all other issues, except perhaps pressing legal ones.
Once the facility is in proper working order, establish a good set of site supplies and parts, and a maintenance schedule and budget that provides not just for the upkeep, but also for the improvement of the facility. Never visit a transmitter site without making some improvement in the site's functionality, cleanliness, or supply cache.
If the facility has old equipment, develop a plan for replacing it. To do this the engineer will need to speak the language of management: money.
It pays to go to management with good numbers for any budget, especially for new equipment. Show them the benefits of the new equipment. Does it use less power? How much? Does it take less maintenance? Is it solid-state instead of tube? Show the savings in eliminated tube costs. Make the numbers tell the story. Another thing to consider is whether the equipment be leased? Do the homework. Get programming on your side — even sales. It's hard to sell a product that's not on the air, or that sounds bad. Be creative, even if you're just trying to get a new piece or two of equipment. It never hurts to be perceived as a team player, either.
As with new sites, sometimes the purchase of good used equipment is a smart move. Don't get fixated on the all-or-bust mentality. Compromise is often the order of the day.
It's useful to establish end-of-life criteria for each piece of equipment at a site; some calendar date or failure point after which it is clearly time (and hopefully budgeted) to replace that equipment. Once that date or condition arrives, stick to the schedule. Don't let anything be a sacred cow. Every piece of equipment at a radio station has a useful life span, beyond which trying to maintain it is no longer smart engineering. Don't be afraid to put a value on it.
Transmitter site maintenance goes beyond the transmission equipment. Vegetation, like this section of tree that grew into a guy wire, must be cleared from the site regularly.
A site should always be thought of as dynamic, never as fixed. This year management may only replace a few parts, but next year the station may need a new audio processor, a new remote control or even a new transmitter or tower. The budgets should reflect this. Don't let management get the idea that the entire equipment set at a site is set and need not be looked at until it comes time to completely rebuild that site. Even worse, don't provide the feeling that the site will last forever. The “state-of-the-art” changes all the time. Look at the number of generations of audio processors developed recently. Budget in such a way that the site is not falling hopelessly behind. Get management to replace something every year at every site, even if it's only to upgrade the firmware in the remote control, so they don't get the impression that they can write off upgrades.
The equipment that can't be replaced must be maintained. Get in there and clean. Even at sites without water, it's easy to bring containers of water, alcohol or other solvent or surfactant, large enough to clean any equipment or mop the floor.
Pay attention to how a transmitter is vented and what effects that has had on its level of cleanliness. In terms of transmitter cleanliness, it pays not to use an extern-ally-vented air system, but instead to install a sufficient air conditioner to handle the heat load of the transmitter, keeping the transmitter in a closed system. This re-duces the dirt in the transmitter — dirt that ends up in the tube socket and on the HV supply wiring or gets sucked into blower bearings and deposited onto heat-sink fins.
The older the equipment, the more aggressively it needs to be maintained. Don't forget to change old electrolytic capacitors, old relay contacts or old bleeder resistors. Keep all the indicator lights working. Sometimes this requires coming up with innovative ways of doing that, such as using solid-state light bulbs, reduced voltages or shutting off the voltage to the indicators when no one is there to see them.
Site and building maintenance
Be proactive. Look for things like peeling paint and rotting boards before the whole TX building wall is sagging. Don't let weeds become overgrown. Keep the road passable. Don't let locks get rusty or else they will break a key at 3 a.m. in the rain.
Spending time at transmitter sites is usually not fun, and all too often management's attitude seems to be that if the engineer isn't at the studio, he isn't working. But it pays to stay ahead of the curve. An engineer who only visits his transmitter sites when there is an emergency is just asking for trouble.
Any budget worth the paper it's printed on should take into account building maintenance, tower painting and other infrequent occurrences. If management is reminded that these items are on the horizon, even if it's not this year or next, they'll be much more willing to budget the money when the time comes than if it's sprung on them.
A robust transmission system is not just within the reach of big-city engineers. I have seen nicely equipped sites in small towns, and I have seen some poorly maintained sites in big cities. Creating a first-class site is possible with a little help from management. Attitude will go a long way toward obtaining that help. So, next time you go to a transmitter site, bring some fuses, and a bottle of water, and a flashlight, and …
Patton is president of Michael Patton and Associates, Baton Rouge, LA.
Acceptable Use Policy blog comments powered by Disqus
[an error occurred while processing this directive]
Today in Radio History
The history of radio broadcasting extends beyond the work of a few famous inventors.
EAS Information More on EAS
The feed provides feeds for all US states and territories.
Need a calendar for your computer desktop? Use one of ours.
Information from manufacturers and associations about industry news, products, technology and business announcements.
When Northern Community Radio set out to build a new community radio station in rural northern Minnesota 38 years ago, naysayers said that it would be broadcasting “only to a bunch of gophers
Browse Back Issues[an error occurred while processing this directive]
Also in the July Issue
- Trends in Technology: Robust IP STL
- LPFM on The March
- RF Engineering: Modern Modulation Techniques
- Field Report: Tascam TH-2000 Headphones
- Battery Maintenance: Testing and Charging