"Ralph Mowery" wrote in
m:

....
That is what I am using on a home built version. Using a 4:1 voltage
balun at the feedpoint and the ferrite bead type about 20 feet down
from the feedpoint.

The ferrite choke is doing something as it gets warm while running
around about 1 KW to the antenna. Doesn't heat up when going into a
dummy load.

I am not surprised at your results with a dummy load. If it is a well
screened unbalanced dummy load, you should expect zero dissipation in the
balun cores.

The fact the balun cores are heating in the antenna scenario indicates
there is some common mode current. You probably have no idea of the
current.

Something to keep in mind is that the average power of uncomressed voice
SSB is about 3% of PEP, so if your 1kW was uncompressed voice SSB, the
average transmitter power might be more like 30W, or half that in a 50:50
over scenario over the long term.

Another thing is the ferrite toroids heat and cool very slowly, so the
operating temperature might still be rising half an hour after the
transmitter is applied (so long as you haven't exceeded their Curie
temperature).

It would not surprise me if the common mode choke consumes a significant
portion of transmitter power on some bands, the portion will depend a lot
on your own scenario.

Owen

"Owen Duffy" wrote in message
...
"Ralph Mowery" wrote in
m:
..

Something to keep in mind is that the average power of uncomressed voice
SSB is about 3% of PEP, so if your 1kW was uncompressed voice SSB, the
average transmitter power might be more like 30W, or half that in a 50:50
over scenario over the long term.

Another thing is the ferrite toroids heat and cool very slowly, so the
operating temperature might still be rising half an hour after the
transmitter is applied (so long as you haven't exceeded their Curie
temperature).

It would not surprise me if the common mode choke consumes a significant
portion of transmitter power on some bands, the portion will depend a lot
on your own scenario.

Owen

I was running the amp around 1 KW with a carrier so the power was a constant
KW.
I only felt the choke while testing on 80 meters. It got warm, but not hot
after about 5 minuits of applied power while hooked to the antenna. Never
got even warm just going into the dummy load.

While I don't know what the choke actually does to the outgoing signal, my
reasoning was to try and keep the unradiated power from comming back in the
the shack and causing problems.

On Tue, 14 Sep 2010 21:18:00 -0400, "Ralph Mowery"
wrote:

It got warm, but not hot
after about 5 minuits of applied power while hooked to the antenna.

Hi Ralph,

Then the loss is trivial. On 80M the Z should be sufficiently high
enough to prevent a large current to develop a node at that point on
the line - it remains to be seen if you need another one further down
to suppress induced current that would then slide into your shack (you
would be complaining of it by now, however).

73's
Richard Clark, KB7QHC

On 9/14/2010 5:09 PM, Owen Duffy wrote:

...
It would not surprise me if the common mode choke consumes a significant
portion of transmitter power on some bands, the portion will depend a lot
on your own scenario.

Owen

Yep, why I don't like windoms ... unless he has discovered a zero point
energy source, his RF IS heating those beads ...

Regards,
JS

On 9/14/2010 5:09 PM, Owen Duffy wrote:
"Ralph wrote in
m:

...
That is what I am using on a home built version. Using a 4:1 voltage
balun at the feedpoint and the ferrite bead type about 20 feet down
from the feedpoint.

The ferrite choke is doing something as it gets warm while running
around about 1 KW to the antenna. Doesn't heat up when going into a
dummy load.

I am not surprised at your results with a dummy load. If it is a well
screened unbalanced dummy load, you should expect zero dissipation in the
balun cores.

The fact the balun cores are heating in the antenna scenario indicates
there is some common mode current. You probably have no idea of the
current.

Something to keep in mind is that the average power of uncomressed voice
SSB is about 3% of PEP, so if your 1kW was uncompressed voice SSB, the
average transmitter power might be more like 30W, or half that in a 50:50
over scenario over the long term.

Another thing is the ferrite toroids heat and cool very slowly, so the
operating temperature might still be rising half an hour after the
transmitter is applied (so long as you haven't exceeded their Curie
temperature).

It would not surprise me if the common mode choke consumes a significant
portion of transmitter power on some bands, the portion will depend a lot
on your own scenario.

Owen

Even worse than that! A lot will only consider the loss in the
transmitted signal of such an antenna, perhaps even call it "trivial."
However, the received signal will suffer from exactly the same losses
.... while even losing 500 watts of a 1KW signal can be considered
"trivial", losing 50% of ones received signal is NOT!

Regards,
JS

Even worse than that! A lot will only consider the loss in the
transmitted signal of such an antenna, perhaps even call it "trivial."
However, the received signal will suffer from exactly the same losses
... while even losing 500 watts of a 1KW signal can be considered
"trivial", losing 50% of ones received signal is NOT!

Regards,
JS


3dB is still only 3dB regardless of where it happens in the link budget!!

Jeff

On Sep 15, 6:18*am, John Smith wrote:
... while even losing 500 watts of a 1KW signal can be considered
"trivial", losing 50% of ones received signal is NOT!

That depends on the signal to noise ratio. If the signal to noise
ratio remains the same while 50% of one's signal is lost, the dynamic
range of a low-noise HF receiver usually makes up for it. Witness the
Beverage antenna where 99% receive power loss is tolerated: (from
Wikipedia)

"While Beverage antennas have excellent directivity, because they are
close to lossy earth they do not produce absolute gain (typically -20
to -10 dBi). This is rarely a problem, because the antenna is used at
frequencies where there are high levels of atmospheric radio noise."
--
73, Cecil, w5dxp.com

On 9/15/2010 4:51 AM, Cecil Moore wrote:

...
That depends on the signal to noise ratio. If the signal to noise
ratio remains the same while 50% of one's signal is lost, the dynamic
range of a low-noise HF receiver usually makes up for it. Witness the
Beverage antenna where 99% receive power loss is tolerated: (from
Wikipedia)

"While Beverage antennas have excellent directivity, because they are
close to lossy earth they do not produce absolute gain (typically -20
to -10 dBi). This is rarely a problem, because the antenna is used at
frequencies where there are high levels of atmospheric radio noise."
--
73, Cecil, w5dxp.com

Cecil,

If a mere loss of 10% drops you too close to the sensitivity threshold
of your receiver, your ability to pull out a weak signal just suffered
the kiss of death ... 100w on a kw might not even be noticed on the
other end ...

Regards,
JS

In message , John Smith
writes
On 9/15/2010 4:51 AM, Cecil Moore wrote:

...
That depends on the signal to noise ratio. If the signal to noise
ratio remains the same while 50% of one's signal is lost, the dynamic
range of a low-noise HF receiver usually makes up for it. Witness the
Beverage antenna where 99% receive power loss is tolerated: (from
Wikipedia)

"While Beverage antennas have excellent directivity, because they are
close to lossy earth they do not produce absolute gain (typically -20
to -10 dBi). This is rarely a problem, because the antenna is used at
frequencies where there are high levels of atmospheric radio noise."
--
73, Cecil, w5dxp.com

Cecil,

If a mere loss of 10% drops you too close to the sensitivity threshold
of your receiver, your ability to pull out a weak signal just suffered
the kiss of death ... 100w on a kw might not even be noticed on the
other end ...

As a Windom is only likely to be used on the HF bands (and probably
mainly on the lower HF bands), I would have thought that a few dB of
attenuation would have negligible effect on the SNR.
--
Ian

On 9/15/2010 5:30 AM, Ian Jackson wrote:

...
As a Windom is only likely to be used on the HF bands (and probably
mainly on the lower HF bands), I would have thought that a few dB of
attenuation would have negligible effect on the SNR.

There are "Windom only baluns?" I thought that was something they just
told the newbies!

Regards,
JS