Conelrad in Boston area

[dan.strassberg@att.net]

I guess Mark missed my first post in this thread, in which I speculated about which Boston-area stations were on 640 and which were on 1240. In response to a later post by Eli Polonski, I admitted that I had overlooked 1330 and speculated that I had probably overlooked others. For reasons of compatility of antennas and ATUs (not phasors; the ND operation meant phasors weren't used--which was a damned fine idea; AM phasors are as frequency-sensitive as can be), low-on-the-dial stations must have been assigned to 640 and high-on-the-dial stations to 1240. However, unless a station went to greater lengths than most did (or happened to operate normally on its ConElRad frequency), the antennas were not properly tuned. So efficiency must have suffered at least a little.
--
dan.strassberg@att.net 
eFax 707-215-6367


-------------- Original message from markwa1ion@aol.com: -------------- 


> I don't doubt Dan's assertion that different stations may have been 
> used at different times. 
> 
> There still could have been technical limitations to which stations 
> could transmit on which frequencies effectively. Most likely 640 would 
> not have emanated from a station designed for above 1200 kHz, since the 
> shorter antennas would be quite inefficient. On the other hand, any 
> station could have likely radiated a decent signal on 1240. 
> 
> On the occasions I listened in 1961, the 1240 signal was definitely NOT 
> strong enough to be from WCOP-1150's site on Concord Avenue in 
> Lexington, less than 2 miles away from Arlington. I think that the 
> stations normally on 1260 and 1330 would have been possible candidates. 
> 1330 was a bit stronger than 1260 but both of these were (/are) far 
> weaker than 1150, 1030, 850, 680, and 590. 
> 
> 640 did seem strong enough to be from either the 590 or 680 site. Both 
> stations could have been utilized in the round-robin sequence. 
> 
> If 630 in RI was being used to provide coverage on 640 to Providence 
> and either 590 or 680 to cover Boston, one would think that there would 
> be quite an interference zone extending down US-1 from Dedham through 
> Sharon to Walpole and Mansfield. Admittedly if the frequencies were 
> precisely controlled within a few Hz and the program feed perfectly 
> synchronous, the effect of the overlap would be minimal. 
> 
> I'm not sure that all content was identical and perfectly-synched 
> nationally or if there were localizations in content specific to cities 
> covered by given outlets. 
> 
> I seem to remember that with many domestic frequencies vacated during 
> the tests, it gave more opportunities to pick up daytime groundwave 
> signals from Montreal and the Canadian Maritimes. 
> 
> Mark Connelly, WA1ION - Billerica, MA 
> 
> -----Original Message----- 
> From: Dan.Strassberg 
> To: markwa1ion@aol.com; boston-radio-interest@rolinin.BostonRadio.org 
> Sent: Fri, 23 Nov 2007 10:41 am 
> Subject: Re: Conelrad in Boston area 
> 
> 
> The whole idea was that you could not do direction finding and  
> especially that enemy aircraft cound not do direction finding! There  
> was not _A_ 640 transmitter or _A_ 1240 transmitter. The various  
> participating AM stations in a region (such as greater Boston) were  
> divided into two groups--a 640 group and a 1240 group. The program  
> material was fed to all participating stations (I think via a land  
> line). The several stations in a group would go on the air for a few  
> seconds apiece in a round-robin sequence. I think that the order of  
> the round robin and the precise amount of time (number of seconds)Â  
> that each station would stay on the air in the sequence varied minute  
> by minute--controlled by signals sent down the line with the program.  
> The idea, I gather, was to make each iteration of the round robin  
> different from the others. Given that the system was set up in the  
> early '50s, the algorithms that varied the sequences in real time were  
> probably not very complex because they were likely implemented by some  
> rather primative mechanical switching technology--a rotating drum,  
> maybe.  
> Â  
> Anyhow, my understanding is that all participating stations were to  
> operate ND and that the maximum power of any station during ConElRad  
> operation was to be 5 kW. There may have been a minimum--I'm guessing  
> 250W--but I don't know that.  
> Â  
> If the signals during the test you heard appeared to be coming from a  
> single source on each frequency, the technology must have improved  
> considerably from the test I heard in Troy NY in the mid '50s. It was  
> very obvious when the transmitter switched and because of the smaller  
> number of stations in the market, there were gaps in the transmissions  
> (when no station occupied the time slot). The designers of the system  
> had apparently foreseen this problem (shame on them if they hadn't; it  
> was pretty damned obvious), so the messages repeated many times--IÂ  
> imagine, by use of an endless tape loop.  
> Â  
> BTW, ConElRad was developed in response to Pearl Harbor; the Japanese  
> aircraft had used the signals from either KGMB or KGU as directional  
> beacons. As with so much Civil Defense technology, ConElRad was  
> designed to fight the last war and not a war that used different  
> weapons--guided missiles, for example.  
> Â  
> -----Â  
> Dan Strassberg (dan.strassberg@att.net)Â  
> eFax 1-707-215-6367Â  
> Â  
> ----- Original Message ----- From: Â  
> To: Â  
> Sent: Thursday, November 22, 2007 1:15 PMÂ  
> Subject: Conelrad in Boston area  
> Â  
> > When I heard a Conelrad test in 1961 (at age 12), the 640Â  
> > transmitter was strong and 1240 was much weaker.  
> >Â  
> > I was living in Arlington, MA at the time, right next to Menotomy  
> > Rocks Park and 500 ft. north of Route 2 / Belmont town line.  
> >Â  
> > The 640 signal was good enough to be from either 590 (Medford) or  
> > 680 (Burlington): both local-quality then as now of course.  
> >Â  
> > 1240 may have been from 1260 on the Quincy-Milton line, hardly a  
> > "barn-burner" signal in Arlington but fine in Boston and nearby  
> > South and North Shore areas.  
> >Â  
> > At the time I was under the likely-incorrect illusion that the 640Â  
> > and 1240 rigs were at the Framingham (or Natick?) Civil Defense  
> > facility.  
> >Â  
> > Since I was so convinced that these transmissions were from  
> > Framingham-Natick, it didn't occur to me to take any  
> > direction-finding cuts at the time. Because I wasn't driving yet, IÂ  
> > would have had to take a few bus rides to get enough DF lines to  
> > triangulate these accurately.  
> >Â  
> > Happy Thanksgiving everybody !  
> >Â  
> > Mark Connelly, WA1ION - Billerica, MAÂ  
> >Â  
> > <<Â  
> > -----Original Message-----Â  
> > From: boston-radio-interest-bounces@tsornin.BostonRadio.org  
> > [mailto:boston-radio-interest-bounces@tsornin.BostonRadio.org] On  
> > Behalf Of  
> > Kevin Vahey  
> > Sent: Wednesday, November 21, 2007 9:47 AMÂ  
> > To: Dan.Strassberg  
> > Cc: boston-radio-interest@bostonradio.org  
> > Subject: Conelrad in Boston area  
> >Â  
> > Back in the 50's and early 60's national alerts were to be  
> > transmitted  
> > by Conelrad at 640 and 1240 on the dial.  
> >Â  
> > I recall one afternoon in the early 60's that all Boston ( and  
> > perhaps  
> > it was nationwide ) stations signed off for a Conelrad test and  
> > listeners were asked to go to 640 or 1240 for instructions.  
> >Â  
> > Where were the Conelrad transmitters liocated for Eastern Mass?  
> >>>Â  
> > 
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