history – Page 7 – Engineering Radio

The Raytheon RL10 Limiting Amplifier

Update: Apparently this is quite interesting to a number of people. I have rescanned the manual, properly compressed it and which you may find it here.

Found this manual at one of the older transmitter sites:

Raytheon RL10 limiting amplifier manual cover

The entire manual is available for your reading pleasure here: Raytheon RL10 limiting amplifier

As this is an older design than either the Gates Sta level or the Collins 26U, it may not be as useful to tube audio enthusiasts.

The main issue with the Gates and Collins unit is the GE 6386 remote cutoff triode used, which were great tubes, but very difficult to come by these days. This design calls for a 1612 or 6L7, which is a pentagrid amplifier. Feedback is provided by the screen of the following stage, a 6SJ7GT. Anyway, perhaps it will give somebody some idea of how to make a good tube compressor limiter.

Suppression of ideas

I found this video called Empire of Noise about broadcast radio jamming. It seems to be about ten years old and is a post-cold War documentary about the jamming of radio signals by the USSR, Warsaw Pact counties, and China. It is an interesting look into the extent and expense that governments will go to suppress counter thoughts and ideas.

The video is quite long, and there are stretches of jamming noise that can be annoying, but perhaps that is the point. It is worth the time if interested in history and radio broadcasting. You know what they say about history; those that do not understand history are destined to repeat it.

A few of the highlights:

The former Soviet Union had the most extensive jamming network of anyone on Earth. There were groundwave jamming centers in eighty-one Soviet cities which consisted of approximately 10-15 transmitters each in the 5 KW covering the medium and shortwave frequencies.
Each groundwave jamming station consisted of a transmitter site and a receiver/control site. The receiver site possessed lists of frequencies to monitor, when objectionable material was heard, the jamming transmitters were turned on.
There was a skywave jamming network consisting of 13 jamming stations with 10 or more 100-200 KW transmitters in each. There were some transmitters in the 1,000 KW power range. These were located in Krasnodar, Lvov, Nikolaev, Yerevan, Alma-Ata, Grigoriopol, Sovieck, Novosibrisk, Tashkent, Khanbarovsk, Servdlosk and Moscow (some of these names may have changed). These operated in a similar fashion to the groundwave jammers.
After the sign-off of government stations, Soviet jammers sent a blanketing signal on the IF frequency (most likely 455 KHz) of receivers to effectively block them from receiving any station while USSR government stations were off the air.
Baltic states had 11 jamming stations with approximately 140 transmitters
Ukraine had approximately 300 Jamming transmitters.
Warsaw Pact countries had extensive medium-frequency jamming networks.
It is estimated it takes about 20 times the transmitted power to jam any one signal.

The entire jamming network was hugely expensive to equip and operate, costing several tens of millions of dollars per year.

It is interesting that the US position in all of this was:

Everyone has the right to seek, receive and impart information through any media and regardless of frontiers. Jamming of radio broadcasts is condemned as the denial of the right of persons to be fully informed concerning news, opinions and ideas.

Sounds perfectly reasonable. The free exchange of ideas and information over the internet is something that should be guarded carefully and should not be restricted or censored. Perhaps somebody should inform Congress.

As requested: The old WSBS studio building

Alan asked if I should ever find a picture of the old WSBS studio building to publish it. Here it is:

I found this above the coffee machine in the lobby, nicely matted and framed. I didn’t want to ruin the framing job, so I took a picture of the picture under glass and cropped it, so thus the quality could be better.

I believe this is the original tower from 1959. The current tower stands on a taller concrete pedestal and is further away from the road. I think the roadway was widened and raised at some point, thus the new building sits higher in relation to the tower base. In any case, it little bit of radio history.

Radio Caroline, 49 years after

Radio Caroline went on the air forty-nine years ago this weekend, broadcasting from the MV Caroline off the coast of England. Why is this important? Before offshore broadcasting was attempted, in Europe the only radio stations (and TV) were government owned. As such, they had a monopoly over the airwaves and were very restrictive on which groups or types of music they allowed to be broadcast. Many of the so-called “British Invasion” groups like The Beatles, Rolling Stones, The Who, The Kinks, etc got their first airplay on offshore radio stations like Radio Caroline or Radio London.

This video “Radio Caroline – A Day in the Life,” shows what it was like to be an offshore broadcaster:

By the haircuts and music, that appears to be sometime in the eighties.

Check out the Radio Caroline website for more information. From 1983 onward, Radio Caroline was broadcast from the MV Ross Revenge. This is an overview of the Ross Revenge transmitter hold. The movie “Pirate Radio” is loosely (very loosely, by most accounts) based on Radio Caroline/Radio London composite.

Radio London was one of the other well-known offshore radio ships.

I am sure that there are other tribute sites with lots of technical information on how they broadcast. Much of offshore radio was outlawed in the late 1960s by several European countries. Radio London signed off on August 14, 1967. Radio Caroline continued on in various iterations until about 1991 or so.

WBCQ is airing a radio ships special on Sunday, March 31, 2013, at 5,110 KHz starting at 6 pm Eastern daylight time (2200 UTC).