ne1s at securespeed.us
Tue Jun 22 19:57:23 EDT 2010
Bernie Doran wrote:
> Hi Larry: what a dinosaur!!! you might even be older that I am. I
> have not heard an 80 AM station since 1950s. but that sure qualifies
> for a few feet. I wonder if anyone ever thought there was something
> wrong with their xmtr. bet you could tell them that you are setting it
> for side band the way TV does!! Bernie
Yep, vestigial sideband.
Nope, you're older, but I probably have older gear!
The first time I got a report like that I didn't think much of it. The
second time it was from I a guy whose technical expertise I knew and
trusted, so I took it as accurate. At first I couldn't think what might
make a classic plate-modulated class C transmitter have asymmetric
sidebands, and wasn't coming up with anything for a satisfying
explanation (mobile transmitter was/is an Elmac A-54H, class C 807
modulated by pair of 5881s). Then I though about how sharp the antenna
tuned, and I came to the conclusion the antenna was acting as a sideband
filter - albeit not a terribly effective one (assuming you wanted SSB -
but who would want that? ;-))
73 and hope to talk to you on the air again this fall/winter,
> ----- Original Message ----- From: "Larry Szendrei" <ne1s at securespeed.us>
> To: "Discussion of AM Radio in the Amateur Service"
> <amradio at mailman.qth.net>
> Sent: Tuesday, June 22, 2010 12:19 PM
> Subject: Re: [AMRadio] Antennas
>>> There have been some interesting cases with short loaded antennas
>>> in the BC band, the bandwidth has occasionally been so narrow that
>>> the AM
>>> sidebands become attenuated! Not going to see that effect in the
>>> bands unless someone is running an antenna only a few feet long!!
>> Correct. This has been observed on my 75M AM mobile signal, with reports
>> of one sideband being attenuated relative to the other. Antenna is a
>> Webster bandpanner ("a few feet long").
More information about the AMRadio mailing list
This page last updated 20 Oct 2017.