Dipoles and the rig's RF ground...
 

"Roy Lewallen" wrote in message
...
I disagree.

I'd venture to guess that the average output power of a 100 watt PEP
sideband rig is no more than about 10 watts unless heavy compression is
being used. And I think you'll find that a 10 watt resistor inside a
typical tuner cabinet -- representing loss of all the transmitted power --
will make a barely noticeable difference in the cabinet temperature.

Well for heaven's sake of course! Who would use SSB to make a test like
this? Put it on CW and put a brick on the key. Come back after dinner. Then
you'll know.

Add to that the fact that the thermal time constant of the tuner is
probably longer than the typical transmitting session, so the power needs
to be averaged over the receiving periods, too.

Average, shmaverage. 100% duty cycle during the test.


If you're running a kW, you're up to 100 watts or so during transmit only.
But can you tell the difference with your "calibrated" hand between 1 dB
loss in the tuner (25 watts), 3 dB loss in the tuner (50 watts), or 100%
of the power lost in the tuner (100 watts)?

Between 25, 50 and 100? You betcha, although calibration of hand might have
to be checked.
Remember, we're not talking NIST here, just an idea of what's happening.

I'd love to see the results of a double-blind study where a measured tuner
loss is compared with an estimate made using Bill's method. But I think
the chances of that are about the same as finding a double-blind study of
the audio quality enhancement of $1000 speaker cables.

Bill's method will be less accurate, more cost effective and good enough.
:-)

Bill, W6WRT

Dipoles and the rig's RF ground...
 

Bill Turner wrote:

Well for heaven's sake of course! Who would use SSB to make a test like
this? Put it on CW and put a brick on the key. Come back after dinner. Then
you'll know.
. . .

So that's where those unidentified carriers that stay on for hours come
from. I'd always wondered.

Roy Lewallen, W7EL

Dipoles and the rig's RF ground...
 

On Wed, 11 Jan 2006 18:44:00 -0800, Roy Lewallen
wrote:


I'd venture to guess that the average output power of a 100 watt PEP
sideband rig is no more than about 10 watts unless heavy compression is
being used. And I think you'll find that a 10 watt resistor inside a

Roy, I did some experiments a few years back when the FCC OET formed a
view that the average power of an SSB voice signal was something like
40% of PEP. My experiment was to modulate a TS440 normally with ALC,
with and without compression, and to analyse the audio captured from a
comms monitor. The ratios averaged over 30s that I obtained were -13dB
and -11dB. Those numbers are consistent with the practice in carrier
telephone systems in estimating the power of a n channel multiplex.

Later, I have made the same measurements off-air with FSM which
reports measurements with an average responding detector, RMS
detector, quasi peak detector and peak detector. The results averaged
over seconds were -10 to -15dB. I have no idea where OET got -4dB
(averaged over 6 minutes).

I don't doubt that it is possible to get several dB loss in an ATU,
but it says more about the understanding of the person using it in
that way than the basis for a law for tuner loss.

A chap was telling me on air a few weeks back how good his MFJ tuner
was, it could tune anything. He got 1:1 and discovered he didn't even
have the aerial connected, how good is that! I suggested he take the
covers off and see if the coil support strips had softened / deformed
/ charred. How could I tell him to stop viewing the world through an
SWR meter?

Owen
--

Dipoles and the rig's RF ground...
 

"Owen Duffy" wrote -

How could I tell him to stop viewing the world through an
SWR meter?
=========================================

Easy! Just tell him he has never viewed the world through an SWR
meter. He hasn't got one. He has a TLI. smiley
----
Reg.

Dipoles and the rig's RF ground...
 

ORIGINAL MESSAGE:


"Roy Lewallen" wrote in message
...

So that's where those unidentified carriers that stay on for hours come

from. I'd always wondered.

Roy Lewallen, W7EL

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Huh-uh. I do some testing on the air, but always at the appropriate times.
Ten meters in the wee hours of the morning, 80 meters at high noon, etc. I
don't QRM and I do identify.

Bill, W6WRT