The sound of an ATU

I am not generally given to nostalgia as it is often a luxury I cannot afford. However, there are some times when I think; I remember the first time I experienced that. Here is a brief video of the WABC ATU coils singing with modulation:

I believe the arc at the 23-second mark came from the Delta base current toroid sample transformer and was due to heavy modulation. Sid, shouting into the microphone again!

The current sample toroid is at the highest impedance point in the system and the voltage exceeds 5KV on the positive modulation peaks. There are also some little black flies that like to fly into the gap between the antenna output conductor and the toroid sample. When I clean up the ATU every quarter, I find many dead flies below the base current sample toroid. A 50,000-watt fly zapper. Fortunately, the DX-50 doesn’t seem to notice this and keeps chugging along.

After about a minute thirty I realized I was probably exceeding my 6-minute SAR and left the ATU building for a while.

Salvaged classic equipment

During the early days of COVID, we were engaged to move a studio out of an old location in a hurry. There had been a long-simmering dispute with the landlord, who finally changed the locks (illegally), but then gave 30 days’ notice, and so on. Regardless, we were building a new studio a few blocks away and were told to take anything usable, which we did.

I noticed the old RCA on-air light for one of the studios and the owner said he’d like to have that installed at the new place. There were two other ones that were not working. In total, we ended up with three of these:

RCA M-11717 on-air warning light

As far as I can tell, they dated from around 1960 and were filthy. Sixty years of dust, dirt, cigarette smoke, etc needed to be scrubbed off of them.

On-air lights cleaned

The original light bulb was a bi-pin 110-volt incandescent lamp. Over the years, the sockets became brittle and fell apart.

Rather than trying to source replacements for the lamp holder, I figured it was easier to install a 12 VDC LED module. That way this would become a low-voltage device and the LED module should last for as long as the studio is in use.

RCA M-11717 on-air light updated
Bench Test
On-air lights install

I took the two best units and installed them in the new studio. One of those units needed minor touchups to the black paint. The third unit’s paint was in bad shape. I opted to strip off all the black paint and repaint it, this time with red.

This is fine

How’s the weather? Well today, it will be orange outside.

3rd Avenue, Manhattan, no filters
The Manhattan sun, about 2 pm

No need to panic, however. Something or other about wildfires in eastern Canada is the cause.

3M P-100 Protective respirator

Fortunately, I have some protective gear in the vehicle. I always carry a hard hat, high vis vest, steel towed boots, and this mask. It comes in handy if there is mold or in this case smoke. A P-100 respirator will filter out Organic Vapors/ Acid Gases (chlorine gas, hydrogen chloride/sulfur dioxide or chlorine dioxide or hydrogen sulfide) – Class 1 and Particulate.

The P-2.50 Particulate monitor had a peak of 248 micrograms per cubic meter, which is very unhealthy.

Doing a bit of outside work today

I had to do my normal weekly outside maintenance items. Looks silly, I know, but I feel great! This was about three o’clock after the worst of the orange had passed.

This, on the other hand, is slightly worrying…

Cellular work on a skirted tower

Cell carriers generally do not like working on AM towers. It is out of their comfort zone and adds a layer of complexity to the project. However, sometimes they don’t have a choice, mainly when there is an existing site and they need to make changes. We have also had mixed results with tower contractors employed by various cell carriers. In one incident, a contractor showed up and re-tensioned the guy wires breaking all of the porcelain insulators. Another time, a contractor showed up to install footings 10 feet away from the tower and ripped up all the ground wires. One tower climber found one of the skirt wires was in his way, so he cut it off with a hack saw.

Those experiences demonstrate that it is far less expensive to have somebody on site while tower contractors are doing installation work on any skirted AM tower. And so it was today.

AT&T 5G sector assembled waiting for lift

This tower has two AM stations diplexed as well as two FM translators combined into one Nicomm antenna. We did before measurements on the AM stations using an OIB-3. Once the installation is done, we will do the after-measurements and then assist the licensee with any FCC 302 filings if the base impedance has changed significantly.

WENU, WMML W250CC and W245DA tower
Lifting the North Sector

With each lift, I went out to the base of the tower and made sure that the skirt wires were clear of the mounting brackets and not touching anything else. The tower crew was Russian speakers. When they asked if the transmitter was still on, which was kind of comical (he motioned to the skirt wire, made like he was grabbing it, then jerked around like he was being electrocuted). I had to wrack my brain to try and remember: Передатчик выключен. The literal translation is “Not working.” The difference between “working” and “not working” is one consonant at the beginning of the second word which is pronounced soft for off and hard for on.

This site was the subject of a previous post: A tale of five signals.