[Boatanchors] Short Wave Broadcasts

[Richard Knoppow]

----- Original Message ----- 
From: "Sheldon Daitch" <SDAITCH at bbg.gov>
To: "Rob Atkinson" <ranchorobbo at gmail.com>; "Boat Anchors 
List" <boatanchors at mailman.qth.net>
Sent: Saturday, April 19, 2014 1:23 AM
Subject: Re: [Boatanchors] Short Wave Broadcasts


Rob,

wish we had had this discussion 25 years ago, and I could 
have checked the AME signals from Greenville for audio 
quality.

Remember, too, for the VOA use, those AME transmissions were 
for program feeder service and the receivers were not AM 
receivers, but SSB receivers - almost always the RCA SSB-R3 
series in the latter years.

VOA isn't the only user of the curtain arrays, but I agree, 
they are on the expensive side.

Formerly WSHB and now WHRI, near Cypress Creek, SC 
32°40'47"N   81°7'53"W appears to have a few curtain arrays, 
actually, 12, per their web site:

http://www.whr.org/Technical-Information.cfm

73
Sheldon

     Along with Leonard Kahn's system for transmitting 
sideband signals on AM transmitters he also developed the 
technology of synchronous detectors for DSB signals. These 
will yield low distortion output from an AM signal 
regardless of whether the carrier is there or not. A low 
level carrier can be transmitted as as pilot to synchronize 
a local oscillator but the synchronous detector synchronizes 
on the basis if the comparative phase of the sidebands.  It 
can't work for a SSB signal although would probably lock on 
a low level carrier if present.  The double sidband and 
synchronous detectors would have worked well for relay use. 
I do remember hearing VOA relay stations who used SSB. They 
may have had a pilot carrier, I don't remember. The audio 
quality of the VOA stations I remember (and I listened a 
lot) was fairly good but usually had heavy processing plus 
many were fed through the AT&T network and had the usual 
distortion one could hear on domestic radio networks on long 
lines.
     I certainly heard the Greenville station but the 
strongest here were those at Dixon and Delano California. I 
saw the curtain antenna at Delano several years ago when 
driving to Sacramento. I wanted to visit but my lady friend 
was very single minded.  Too bad.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com