A few pictures

Some things I have been working on lately:

A nice row of transmitters
A nice row of transmitters

Finishing up a transmitter site rehab.  The BE FM20T is nearly 20 years old.  The BE FM2C transmitters are new.  There is also a rack of new fiber equipment and CODECs.  This site has good utilization; there are three stations on one tower with a shared STL antenna and generator.

Energy Onix ECO-6
Energy Onix ECO-6

Energy Onix ECO-6 tube type transmitter.  One of Bernie’s better designs, a grounded grid tube with solid state driver section.  This one needed some fans replaced and a new tube.

AM transmitter site.  Looks like these vines have not been cut in a couple of years.
AM transmitter site. Looks like these vines have not been cut in a couple of years.

I wonder how much the guy tensions have changed…

Noticed this after some particularly strong thunderstorms
Noticed this after some particularly strong thunderstorms

The reason why you do not use a POTS line phone during a thunderstorm.

USS Slater radio room
USS Slater radio room

I took a tour of the USS Slater, a museum ship in Albany, NY.  The museum has painstakingly restored the ship to its WWII configuration.  The main transmitter is the RCA TBL-8 seen in the left/center of this picture.  This unit put out 200 to 400 watts CW or 150 watts AM phone.  During the hostilities it was turned off as allied ships observed radio silence unless they were sinking (and sometimes even then).

A little ChiFi tube type RIAA phone preamp.
A little ChiFi tube type RIAA phone preamp.

I have been fooling around with this little 6AK5 preamp.  I find it works very well and sounds better than the built in phone preamp on my Kenwood VR-309.  The FU-29 tube amp did not come with a phone preamp.

This is a short video clip of an audio processor at one of our transmitter sites. The fancy lights around the control knob are designed for the program director. They are saying “Buy me… Buy me…”

Ten years on

It was ten years ago that I registered the domain name for Engineering Radio. A few days latter, I put the first post up. It is still there.  Those were different times for me personally and the business in general.  There certainly have been trials, but it has never been dull.

Periodically, I go back through the posts and delete anything that is no longer relevant.  I would estimate about 1/4 to 1/3 of the content has been deleted over the years.  It is a good exercise to go back through and read what I wrote previously.

Currently, the stats are:

  • 787 published posts, there are a few in the wings waiting to be finished
  • 4459 comments
  • Approximately 200 page views per day
  • 170 RSS feed subscriptions

I lost the country counter, but I believe the split is still about 60/40 US readers vs other countries.

I will continue on with this thing for as long as I feel it is worth while.

Last Walk across The Island

Yesterday I took, what I hope to be, my last walk across Pleasure Beach Island in Bridgeport, Connecticut. The task at hand was repairing the antenna array for WICC. There turned out to be several issues which were addressed in turn.

WICC tower feed point, courtesy of NECRAT

The trouble started when the feed line between the ATU and the tower became disconnected during a storm. That consists of a 1 inch copper pipe extending from the ATU feed through insulator up to a brass plate suspended between the four tower legs by hard drawn single 0 copper wire. The feed line separated at the brass plate which, unfortunately, is approximately eighteen feet in the air.

North Tower feed point connection, cold soldered

The feed line was repaired, but not effectively. By the looks of the picture, the brass plate never got hot enough to accept the solder.

After the feed line was re-repaired, other issues became apparent. The base impedance of the tower was still off and the array was still way out of tolerance.

It was noticed that several bypass capacitors on both of the tower lighting chokes where blown open. Those where replaced and the tower lighting chokes where checked for shorted turns. While it is always nice to replace burned out parts, this did not correct the problem.

Finally, we were back at the base of the tower with the defective feed point and a decided to grab the pipe and give it a good shake to see if it came apart again. It did not, but then I realized that that tower was supposed to be back in the circuit and I did not receive any RF burns for my carelessness.

We dug into the ATU and discovered that the input capacitor was marginal and there was a large crack in it. The output capacitor seemed to be completely open. The base current that we were seeing on the base current meter was being induced by the other tower. It all began to make sense.

Bad Capacitor

The parts were ordered and shipped and I made another trip out to install them myself.

Thus, on this particular day, I had my tool bag, an OIB-3 with fresh batteries, my cordless drill, drill bits, and three type 294 mica capacitors. I took the drill because the new capacitors were quite a bit larger than the old ones, so I needed to move the stand off insulators to remount them.

Pleasure Beach pier, foggy day

The walk from the end of the dock to the transmitter site is approximately 900 meters or 0.55 miles, according to google maps. On a nice day, it is a pleasant walk. On not so nice days, it can be less so. It was foggy with light drizzle. Not enough to get wet right away, but enough to get slowly soaked while working on the ATU repairs.

WICC square base self supporting towers, manufactured by Milliken Tower, circa 1924

With the new capacitors installed, I needed to adjust the array back into tolerance, which didn’t take too long. I made a short video of the station running at full power showing the antenna monitor readings for both the day and night patterns. Then packed up and headed back to the dock.

My ride is here

I wanted to take a set of monitor points, but the FIM-41 had been moved to another location. That was fine, I was getting pretty uncomfortable in my wet clothes, so I headed home.

Goodbye, WICC.

Almost Eighteen Years

I do not know what the record is for the longest tube life, however, this particular tube lasted 17 years, 11 months and 23 days.  That’s 157,596 hours.

I had written about this almost five years ago: http://www.engineeringradio.us/blog/2014/12/longest-tube-life/

The last one was last fall: http://www.engineeringradio.us/blog/2018/09/i-almost-hate-to-say-anything-but/

Eimac 4CX12000A power tube, serial number RHH108

This was installed new in a Broadcast Electronics FM20T transmitter which was placed on line on June 6, 2001.  It lasted until May 28th, 2019 with almost no down time.  Towards the end, the emissions started dropping off and we increased the filament voltage up to 10 volts.  When you have to increase the filament voltage, that really is the end for a tube.

The new tube was put in and I carefully marked out the date in the maintenance log.  The hour meter on the transmitter stopped working several years ago.

Prior to this, the longest tube life I’d experienced was an EEV 4CX35000C from an MW-50B transmitter RF section.  When that tube came out, it looked like it have been on fire.