Engineering Radio – Page 109 – One Hundred percent Human Generated Content for your Reading Enjoyment

RoHS and Electronics Reliability

ROHS stands for Restriction of Hazardous Substances Directive. It is a mainly European effort to reduce lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr⁺⁶), Polybrominated Biphenyl (PBB), Polybrominated diphenyl ethers (PBDE) and Acrylamide in electronics and consumer goods.

The main effort appears to be in the reduction of lead in circuit boards and solder. Generally speaking, the reduction of pollutants is a good thing. Lead is toxic, especially to young children. Mercury is a potent neurotoxin. Those other elements and chemicals don’t sound good either.

There are all sorts of green logos and other nice-looking things attached to products that meet the standard.

I feel better, don’t you?

Now for the other side of ROHS. According to Lead Free Electronics Reliability (large .pdf) by Dr. Andrew Kostic, the effort had been hugely expensive with very limited results:

A huge (~ $14B annual revenue) semiconductor manufacturer estimated the annual worldwide Pb reduction per 1,000,000,000 integrated circuits was only equivalent to ~100 automobile batteries.

Wow! That is simply amazing on the face of it. Over the years, I have probably found and carted at least 10 old car batteries to the recycling center for a few dollars each. According to the Kostic paper:

(Computer chip manufacturer) Intel’s efforts to remove lead from its chips have so far cost the company more than $100 million and there is no clear end in sight to the project’s mounting costs

Wouldn’t $100m be better spent on other, more pressing pollution issues? Fukushima, springs to mind.

Further, the replacement metals used in electronics have some problems of their own. They may be better for the environment, however, they lack testing and are

Not optimized for high reliability, severe stress, long life applications

Further, replacing parts in legacy equipment using ROHS parts and solder may present problems with bonds between dissimilar metals. Thus, making field repairs, or any repairs impossible.

Many of the newer solders and circuit boards use Tin (Sn) as the finishing metal. There is a problem with tin, known as Tin whiskers. This was first noted at the Bell Labs in 1947. Small hairs grow out of the surface of the metal, acting as short circuits, and at higher (above 6 GHz) frequency RF, antennas. This happens with other metals such as Zinc, Silver, and Gold.

Silver Sulfide Whiskers on circuit board

As you can probably deduce, this can have certain detrimental effects on the performance of the circuits in question. I can imagine all sorts of strange behavior from controllers and other bits and parts of equipment.

I don’t know how prevalent this is in Europe where the directive has been in effect for 6 years or so. It would be interesting to find out. I also wonder how many US manufacturers are adopting RoHS as the de facto standard in order to do business in Europe.

Troubles at the Tower

Troubles at the AM tower; I don’t know why, it won’t switch power.
Over the phone I can tell, the program director’s day is not going very well.
Press the “day” button but there is no kerchunk, the directional coupler shows the load is junk.
Out into the big field, I go to find the problem quickly and fix it just so.
The wind is cold, the snow is deep, I think of the contract terms I must keep.
Reaching the tuning house, take out the keys, lock, do not be frozen, please.
Once inside, there I find, no big surprise, the mice have been a working this pre-sunrise.
A nest they have build in a most inconvenient place, in the back of the phasor wiring chase.
Oh, the wires they have chewed, the circuit’s destroyed, all for the lack of mousetraps deployed.
As I reach in to clean out the mess, the smell of mouse makes me gag, I confess.
The fuses are blown, the contactor is jammed, perhaps, if I am lucky, I can move it by hand.
A large screwdriver strategically employed, I pry up slowly, further damage to avoid.
The bar thunks up, the contacts engage, the transmitter is ready to apply amperage.
Call on the cell phone, tell them it’s fixed, stand back and watch the base current meter, transfixed.
Then; Up it goes! Wonderful radio frequency current flows!
I clean up, lock the door, lock the gate, carrying bad news the owner will hate.
The damage is grave, the repair bill is steep, if a good relationship with the FCC you desire to keep.
Business is off, the accounts are low, is this really necessary, he wants to know.
The terms of the license are your obligation to keep, getting caught out of tolerance will not be cheap.
Looking forlorn, the owner says in disgust, it is only the AM, but fix it if you must.
Happy as a lark, with a song in my heart, I dig though the manual and order the part.
Time to go home, eat breakfast, brush teeth, take a shower. I have another client to see before the noon hour.

Dedicated to all those who have been there, done that and the breed of RF men and broadcast engineers who are slowly fading away.

Generators and mice

Never a good mix, unfortunately, it usually turns out bad for the mice and sometimes the equipment. This is an Onan GGMA 20 KW propane generator installed in a rural area, not that the location matters that much. Mice will find what they perceive as a safe secure spot to hold up for the winter.

Unfortunately, the mice decided that the generator cooling fan was a good place to make a nest. It probably was until the generator started, then the mice had a quick lesson in centripetal force.

This will require some additional maintenance in the springtime when I change to oil. By that time, the carcasses should be mostly dried out and easier to deal with.

The mice are generally a nuisance, getting into ATU’s, transmitters, electrical panels, spare parts boxes, etc. Once in place, they begin to breed and reproduce. The gestational period for a mouse is 21 days, which means populations rapidly increase creating further problems. If left alone, mice will chew through electrical insulation, control wires, cardboard boxes, packing material, and so on. They tend to carry diseases like hantavirus and bubonic plague.

I don’t usually agree to using poison to get rid of pests, it tends to linger in the environment and accumulate up the food chain. However, judicious use of some type of poison is usually the only way to effectively get rid of a mouse infestation.

Wherever possible, make sure that all openings and holes into equipment and buildings are sealed up. Do not kill snakes and other predators, who will assist in keeping the mice in check. Employ traps and wear gloves when removing dead mice and mouse parts. Beware of fleas.

WNAW North Adams

Originally signed on as WMNB in 1947, it is a Class C AM station on 1230 KHz, one of thousands in the country. Initially, it had a power of 250 watts, upgrading at various times to its current power of 1,000 watts.

WNAW-WUPE-FM, North Adams, Ma circa 2012

What is different about this station is the studio building. It is located in its original place on Curran Highway on the south side of North Adams. The studio is a late Art Deco design, complete with a small glass atrium in the lobby. Like many older radio stations, this installation was built on a raised floor. The walls and doors are all well constructed for maximum sound attenuation. The doors are large, heavy, and solid wood.

WNAW news room, formerly the performance studio — WNAW newsroom, formerly the performance studio

Inside, the original studios are laid out with a control room, a broadcast studio and a live performance room. At one time, the live performance room had a grand piano. Several times per week, live music shows were broadcast on the station. There was a large newsroom, and a big corner office for the General Manager and sales managers.

WNAW studio, looking into the control room. Back in the day, the announcer, whose only concern was announcing, worked in a separate studio from the engineer on duty, who worked console in the control room. The audio level limiting consisted of turning down the level on the console if the announcer started speaking loudly. They often communicated with each other with hand signs through the windows.

At the time that WMNB was signed on, the Adams/North Adams Massachusetts area was in the heart of the northeast manufacturing belt. Sprauge had a capacitor plant in Adams, GE was making plastics in Pittsfield, There were many textile mills still in operation and so on. The population was predominantly working middle class.

Obviously, the console has been changed since those days. The current console is a Audio Arts R-60. This serves as the control room for WNAW and WUPE-FM. The programming for WUPE-FM comes from Pittsfield on a T-1 line. From here, it is relayed to the transmitter site on a 950 MHz STL. WNAW transmitter is located about 2/10 of a mile south of the studio building on Curran Highway. It consists of a skirted self supporting tower with a Gates 1 solid state transmitter.

Equipment racks containing the T-1 equipment, modulation monitors and STLs. Note the very old Moseley TRC-15 remote controls. We have been unwiring these at the transmitter sites and disconnecting the TELCO lines. The transmitter sites now have Sine Systems dial up remote controls.

In 1961, WMNB-FM (now WUPE-FM) signed on the air from a tower north east of downtown, off of Mohawk Trail (MA route 2). It broadcast on 100.1 MHz with an ERP of 1,000 watts using a Gates FM1B transmitter.

WNAW continues on today as a community based radio station and is well liked and supported.