Restoration work on an RCA transmitter

I read through this article about the ongoing restoration work of an RCA SSB T-3 transmitter and found it interesting.  The RCA T-3 transmitter is a 20 KW SSB/ISB HF (2-28 MHz) unit designed for point to point telephony service.  Because SSB requires class A or AB low distortion amplifiers, this is a large unit, even for its age and power levels.

From the looks of the before pictures, this transmitter was in sorry shape.

Here is a brief video of transmitter start up:

These units were designed to be switched on and run at 100% duty cycle from most of their operating lives. That is some heavy iron there.  This particular unit was made in 1959. More here and video part 2:

Anyway, before geosynchronous satellites, HF point to point transmitters were used to make long distance phone call connections and send data and pictures back and forth over long distances. Out in Hicksville, Long Island, Press Wireless ran a data and fax system that used HF for long haul data transmission.  Much of the WWII reporting from Europe and the Pacific Theaters was carried over this system.

Text would be printed out on a mechanical teletype machine at something like 60 words per minute, which was considered fast for the time:

Tuning across the band, one can often hear Radio Teletype (RTTY or RATT) which uses a 5 bit baudot code, 170 Hz shift with 2125 HZ representing a Mark or 1 bit and 2295 Hz representing a Space or 0 bit, which is bit different from the Bell 103 modem specifications. This is what it sounds like at 75 Baud:

So slow you can almost copy that by hand.

The RCA H (SSB T-3) unit above was independent side band (ISB), which means that either side band or both could be modulated independently of the other, thus two channels of information could be transmitted.  SSB bandwidth is about 2.7 KHz, which is good for telephone grade audio or low speed data.

I sort of wish I was living in California again, I’d lend a hand.

HF broadcasting station maintenance

This video shows some of the maintenance required for a HF (AKA Shortwave) broadcast station. It starts with transmission line tensioning, some shots of a curtain array then goes on to show the inside of a transmitter building. Transmitters shown are Harris HF-100 (a 1980’s model tube type PDM design) and Continental 418, but I didn’t see the letter number. They are likely tube modulated units.

These are from the international service of Australia Broadcasting Corporation (ABC), or Radio Australia International.

Maritime Radio Historical Society Night of Nights XIII

Every year on July 12, the Maritime Radio Historical Society (MRHS) commemorates the end of commercial Morse code use in the US. I have a soft spot for Maritime Radio, as that is where I began my radio career.  For nearly one hundred years, ship board radio operators, “sparks” communicated with land based stations using Morse keys and relatively simple low powered transmitters.  The skills gained by a good CW operator could only be attained by time spent sitting watch.

In order to remember those who did that service, several former coastal radio stations fire up transmitters once a year on July 12th.   This year’s frequencies are:

KPH KFS KSM WLO KLB Ship transmit
426 426 488
500 500 500 500
4247 4343 4184
6477.5 6274 6276
8642 8438.3 8658 8582.5 8368
12808.5 12695.5 12993 12992 12552
17016.8 17026 16968.5 16736
22477 22280.5

Festivities begin at 8pm eastern time.  In addition to those frequencies, K6KPH will be on the air on 3550, 7050 14050 and 21050 KHz.

KPH, KFS and KSM are all operated from Point Reyes National Park, transmitters are on Bolinas. This is a video of the transmitter gallery in Bolinas:

Other video of Bolinas Facility:

Former KPH receiver site, Point Reyes National Park:

This is a former coastal station site in Cape Cod, which was torn down:

Lots more information at the Maritime Radio Historical Society site.

Goodbye, RCI 1945-2012

RCI logo
RCI logo

In yet another example of government sponsored international broadcasting ending, Radio Canada International calls it quits after 67 years.  Effective June 24, all broadcasts from RCI’s Sackville shortwave relay site will cease.  All satellite distribution will end and seventy five percent of the RCI workforce will be laid off.  This means the end of almost all RCI original content.  The good news, according to the press release, is that RCI will continue on webcasting.

This is due to budget cuts to the CBC, which administers RCI.  The Canadian Parliament cut the RCI budget from $12.3 million CAD to $2.3 million CAD for 2012.  This cut in expenditures is saving each Canadian resident approximately $0.35 CAD per year.

Thus, this weekend is the last chance to hear RCI or CBCNord Quebec on any HF frequency.

I listened to RCI for many years, until they drastically reduced their English language shortwave broadcasts to North America in 2006.  Simply put, HF broadcasters are folding up shop and moving toward web based distribution networks.  Those HF transmitters are expensive and they do not maintain themselves.

One drawback of this scheme is government censorship.  It is very easy to the government to block access to sites via internet firewalls.  It is very difficult to completely jam a radio station.

And perhaps those considerations are not important.

RCI transmitter site, Sackville, NB
RCI transmitter site, Sackville, NB, courtesy of Wikipedia

I wonder what will happen to their transmitters after sign off?  According to the wikipedia article there are nine HF transmitters in use, with power levels ranging from 100-300 KW.  They are likely to be hauled away and scrapped, the building torn down.