Rick (W-A-one-R-K-T) wrote:
On Sat, 12 May 2007 10:37:13 -0400, Rick (W-A-one-R-K-T) wrote:
Thanks for the pointer. That one was a real eye opener. I always thought
that any angle 90 degrees or greater at the feedpoint was OK. I think
mine is something like about 100 degrees.

Actually I just calculated it out and it's more like around 130 degrees,
or each leg is just 25 degrees down from horizontal. So, according to
Cebik that should be pretty good.

What is the length of your feedline?
--
73, Cecil http://www.w5dxp.com

On Sat, 12 May 2007 12:47:32 -0500, Cecil Moore wrote:

What is the length of your feedline?

That I don't know at the moment. I downloaded your imax.exe program and
ran some numbers.

There sure aren't very many numbers that are good for all bands 160
through 10.

No doubt my feedline is wrong for a lot of frequencies, made more clear by
the fact that there are a few frequencies where my LDG autotuner can't
find a match.

However, how much does the feedline length matter IF the autotuner is able
to find a good match point?

I can get 1.5:1 or better from everywhere in the 160 and 80 meter bands,
and the high end of the 40-meter band (on the low end I can't get below
about 2:1).

I'm about to go outside and try some different feedline lengths.

Rick (W-A-one-R-K-T) wrote:
No doubt my feedline is wrong for a lot of frequencies, made more clear by
the fact that there are a few frequencies where my LDG autotuner can't
find a match.

However, how much does the feedline length matter IF the autotuner is able
to find a good match point?

Some impedances are outside the matching range and some
impedances are barely inside the matching range. Some
of the latter may not be a "good" match point. I model
my antenna systems to get a ballpark idea of what
impedance I am up against and use an antenna analyzer
to fine tune the system.
--
73, Cecil http://www.w5dxp.com

Rick (W-A-one-R-K-T) wrote:
. . .
The only criterion I have available right now is received signal strength.
I don't yet have the resources to do transmit signal strength
measurements.
. . .

Do you expect them to be different? Why?

Roy Lewallen, W7EL

On Sat, 12 May 2007 13:33:16 -0700, Roy Lewallen wrote:

Do you expect them to be different? Why?

Good evening Roy...

Well, yeah... sorta...

Wouldn't one normally expect a "better" antenna to be "better" on receive
(i.e. give a stronger received signal) as well as on transmit?

"Rick (W-A-one-R-K-T)" wrote in message
news
On Sat, 12 May 2007 13:33:16 -0700, Roy Lewallen wrote:

Do you expect them to be different? Why?

Good evening Roy...

Well, yeah... sorta...

Wouldn't one normally expect a "better" antenna to be "better" on receive
(i.e. give a stronger received signal) as well as on transmit?


yes, a 'better' antenna would be... but higher and longer don't necessarily
mean 'better'.

Then it should work fine
yes you do seem to have a problem. maybe if you shrtened it up some.

On May 12, 10:46 am, "Rick (W-A-one-R-K-T)"
wrote:
On Sat, 12 May 2007 09:27:47 -0700, herbert.don wrote:
how far apart are the ends?

Around 235 feet.

You should definitely expect the difference between two antennas to be
the same in terms of signal strength for transmitting and receiving.
However, the antenna which produces the stronger signal isn't
necessarily the better receiving antenna. What counts when receiving is
signal/noise ratio, and the the antenna producing the strongest signal
may well produce a worse signal/noise ratio.

Doing transmit signal tests is entirely useless unless you happen across
someone with a step attenuator who knows how to use it, and the patience
to make many measurements as QSB fades you in and out. A friend of mine
gets perverse pleasure out of the dramatic differences other people
report between "antenna A" and "antenna B", when they're actually the
same antenna.

Roy Lewallen, W7EL

Rick (W-A-one-R-K-T) wrote:
On Sat, 12 May 2007 13:33:16 -0700, Roy Lewallen wrote:

Do you expect them to be different? Why?

Good evening Roy...

Well, yeah... sorta...

Wouldn't one normally expect a "better" antenna to be "better" on receive
(i.e. give a stronger received signal) as well as on transmit?

I have been reading the Inverted Vee thread about the differences in
receive and s/n.

My process of using the tuner is to find the highest noise level,
then, turn on the carrier and fine tune to the lowest SWR. Often I
find that the signal strength isn't as good as it was before tuning.

Assuming the SWR is acceptable when tuned to the best signal, even
though it is not at its lowest, would it be better to leave the tuner
at the best received signal and use the radio with a bit higher SWR?

I am talking about SWR below 2:1, (not 10:1) as measured by the meter
or radio at time of tuning. For me, acceptable SWR for my solid state
rigs is 1.7:1 as 1.8:1 often causes protective circuits to kick in and
reduce power.

Comments?

Buck
N4PGW

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Buck wrote:
I have been reading the Inverted Vee thread about the differences in
receive and s/n.

My process of using the tuner is to find the highest noise level,
then, turn on the carrier and fine tune to the lowest SWR. Often I
find that the signal strength isn't as good as it was before tuning.

Assuming the SWR is acceptable when tuned to the best signal, even
though it is not at its lowest, would it be better to leave the tuner
at the best received signal and use the radio with a bit higher SWR?

I am talking about SWR below 2:1, (not 10:1) as measured by the meter
or radio at time of tuning. For me, acceptable SWR for my solid state
rigs is 1.7:1 as 1.8:1 often causes protective circuits to kick in and
reduce power.

Comments?

Buck
N4PGW

It would be really neat if we had a tuner that would selectively tune
the signal and noise. But alas, we don't. At HF, the signal and noise
are both coming from outside the antenna, so anything we do at the tuner
-- or anywhere between the antenna and receiver -- affects both equally.
The tuner won't affect the received s/n ratio unless you get it so badly
mistuned that you start hearing receiver noise, which isn't likely at
HF. So tune it any way you want.

For transmitting, you're always best off getting as much power to the
antenna as you can. (I mean actual power, not "forward power".) What
you're trying to do is make the best s/n ratio at the other guy's
receiver. You can't do anything about his noise, but for every dB you
increase your signal, you get a one dB improvement in the s/n ratio at
his end. This means having an SWR low enough that your rig doesn't shut
down. Unless you have an extraordinarily lossy transmission line, any
SWR below the shutdown point will get the same amount of power to the
antenna for practical purposes.

At VHF and above, receiver noise is usually greater than atmospheric
noise, so the rules change for receiving antennas. There, you do want to
get as much signal from your antenna as you can in order to get the best
s/n ratio. The rule for transmitting is still the same, though.

Roy Lewallen, W7EL