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-   -   Standing Waves (and Impedance) (https://www.radiobanter.com/antenna/84606-standing-waves-impedance.html)

Fred W4JLE December 27th 05 02:54 AM

Standing Waves (and Impedance)
 
In the setup menu, you can disable unused modes. Go back in and turn it on.

"Cecil Moore" wrote in message
...
Fred W4JLE wrote:
65.75 is the magic frequency. It does appear the WFM mode can not be

used on
this frequency on the 706 MKIIG I have. In the FM position, while

distorted
it is copyable. The radio shows WFM mode, but it certainly isn't in the

wide
mode.


My original problem was with an original IC-706 which I sold.
I'm now mobile with an IC-706MKII with DSP. But my mode switch
switches from FM to AM to FM ... and never shows WFM at all,
not even when tuned to 88-108 MHz so commercial FM or TV is not
worth listening to. I have a Sony Walkman that does receive VHF
TV audio and my CCRadio+ does also.
--
73, Cecil http://www.qsl.net/w5dxp




Cecil Moore December 27th 05 04:47 AM

Standing Waves (and Impedance)
 
Fred W4JLE wrote:
In the setup menu, you can disable unused modes. Go back in and turn it on.


Thanks Fred, success at last. I don't remember ever disabling
WFM mode and, to the best of my memory, I had never accessed
the Q0 setting before. I think I liked my Hallicrafters S-53A
better.
--
73, Cecil http://www.qsl.net/w5dxp

John Ferrell December 27th 05 02:21 PM

Standing Waves (and Impedance)
 
You guys are testing my gray matter today...
The question: Is it possible to detect an FM subcarrier without
receiving the base carrier?

Perhaps another cup of coffee will help...


On Mon, 26 Dec 2005 18:05:38 -0500, "Fred W4JLE"
wrote:

65.75 is the magic frequency. It does appear the WFM mode can not be used on
this frequency on the 706 MKIIG I have. In the FM position, while distorted
it is copyable. The radio shows WFM mode, but it certainly isn't in the wide
mode.

Now I have to get in the circuitry and see why the WFM is not operable on
this band.

"Cecil Moore" wrote in message
. net...
Fred W4JLE wrote:
You can if you tune to the audio offset.


I have run the IC-706 all up and down the channel 3
60-66 MHz frequencies while in College Station, TX
and cannot hear the audio anywhere.
--
73, Cecil http://www.qsl.net/w5dxp


John Ferrell W8CCW

Richard Fry December 27th 05 03:47 PM

Standing Waves (and Impedance)
 
"John Ferrell" wrote
The question: Is it possible to detect an FM subcarrier without
receiving the base carrier?

______________

If you are still thinking of the broadcast television signal, the audio
portion is not a subcarrier -- it is a discrete carrier whose modulation can
be detected by any receiver capable of FM demodulation, and able to tune to
its r-f center frequency.

RF


Cecil Moore December 27th 05 06:09 PM

Standing Waves (and Impedance)
 
Richard Fry wrote:
If you are still thinking of the broadcast television signal, the audio
portion is not a subcarrier -- it is a discrete carrier whose modulation
can be detected by any receiver capable of FM demodulation, and able to
tune to its r-f center frequency.


The confusing part, at least for me, was that the entire passband *can
be* downconverted and then demodulated assuming 4.5 MHz separation. That
doesn't imply a *necessary* condition for demodulation.
--
73, Cecil http://www.qsl.net/w5dxp

Fred W4JLE December 27th 05 06:46 PM

Standing Waves (and Impedance)
 
TV audio is not a sub-carrier. The audio is an independent transmitter from
the aural transmitter.

They may have come up with some other way since I worked at WXEL in the
fifties, but as a fifty's TV set still works today, I suspect the result is
the same.

"John Ferrell" wrote in message
...
You guys are testing my gray matter today...
The question: Is it possible to detect an FM subcarrier without
receiving the base carrier?

Perhaps another cup of coffee will help...





Roy Lewallen December 27th 05 09:22 PM

Standing Waves (and Impedance)
 
Richard Fry wrote:

If you are still thinking of the broadcast television signal, the audio
portion is not a subcarrier -- it is a discrete carrier whose modulation
can be detected by any receiver capable of FM demodulation, and able to
tune to its r-f center frequency.


You've described how it's commonly generated. But is the end result any
different than if it were generated instead by modulation of the main
carrier by an ideal modulation system not having the practical problem
of intermodulation distortion? That is, isn't the end result identical
to a subcarrier?

When I worked in radio broadcasting in the '60s, we generated an FM
(SCA) subcarrier in addition to the stereo subcarrier by modulating the
transmitter. Some stations had multiple SCA subcarriers.

Roy Lewallen, W7EL

Richard Fry December 27th 05 11:04 PM

Standing Waves (and Impedance)
 
"Roy Lewallen" wrote
Richard Fry wrote:
You've described how it's commonly generated. But is the end result any
different than if it were generated instead by modulation of the main
carrier by an ideal modulation system not having the practical problem of
intermodulation distortion? That is, isn't the end result identical to a
subcarrier?

____________

No, in that an aural subcarrier would disappear without a visual carrier to
convey it. TV aural via a standalone r-f transmission system would not.

RF


John Ferrell December 27th 05 11:28 PM

Standing Waves (and Impedance)
 
I like your answer best, probably because I understand how it works!

On Tue, 27 Dec 2005 13:46:45 -0500, "Fred W4JLE"
wrote:

TV audio is not a sub-carrier. The audio is an independent transmitter from
the aural transmitter.

They may have come up with some other way since I worked at WXEL in the
fifties, but as a fifty's TV set still works today, I suspect the result is
the same.

"John Ferrell" wrote in message
.. .
You guys are testing my gray matter today...
The question: Is it possible to detect an FM subcarrier without
receiving the base carrier?

Perhaps another cup of coffee will help...



John Ferrell W8CCW

Roy Lewallen December 27th 05 11:37 PM

Standing Waves (and Impedance)
 
Richard Fry wrote:
"Roy Lewallen" wrote

Richard Fry wrote:
You've described how it's commonly generated. But is the end result
any different than if it were generated instead by modulation of the
main carrier by an ideal modulation system not having the practical
problem of intermodulation distortion? That is, isn't the end result
identical to a subcarrier?


____________

No, in that an aural subcarrier would disappear without a visual carrier
to convey it. TV aural via a standalone r-f transmission system would not.


Sorry, I obviously failed to communicate my question. Let me try again.

With no information other than looking at the composite signal including
video and audio, would you be able to tell if it was generated by two
separate transmitters or by modulation of a single transmitter by the
video and an audio subcarrier? That is, if you could do the modulation
without generation of intermodulation products.

Roy Lewallen, W7EL


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