Six meter preamp
Good morning,
A few days ago I sparked a very good discussion on whether or not I might
need a preamp at the antenna when I got my six meter yagi up. It is up.
It is a 6 element LFA with a 22 foot 9 inch boom length. It is based on
the design by G0KSC. The SWR is 1.0:1 at 50.125 and less than 1.3:1 from 50
to 50.7 MHz.
I use the K3s, KPA500, and KAT500(when necessary). I also have the P3,
which is a very good measuring tool for signal levels, noise baseline,
etc...
The K3s has two preamps built it. I took base line noise measurements with
and without the preamps, on a dummy load and on the antenna as installed at
the tower. There is 320 feet of feedline between the K3s and the antenna.
260 feet is half inch Andrew superflex and the last 60 feet is new LMR
400. There is an RCS 10 remote antenna selector at the base of the tower.
Here are the results:
The scale on the P3 reads in dB. I think it means dBm. I should read the
manual someday.
On the Dummy load with no preamp: -130 dBm
Dummy load with preamp #1: -135dBm , noise in speaker comes up.
Dummy load with preamp #2: -147 dBm noise in speaker "maybe" a little
higher.
Antenna no preamp: -130 dBm
Antenna preamp #1: -135 dBm noise in speaker up "a little"
Antenna preamp #2: -140 dBm noise in speaker noticeably higher.
I have read various opinions as to how much noise increases when the
antenna is connected indicates whether or not a preamp is needed at the
antenna. I don't know how that relates to using internal preamps. But the
fact that there is no difference in noise with and without the antenna when
there is no internal preamp used makes me wonder. What do you think?
I then rotated the antenna and watched the noise base line. It is apparent
that I do not live in a noise free environment. The noise and birdies are
higher when pointed at my house (250 feet away). There is a really quiet
spot 15 degrees off of my house at 45 degree heading. It is 3 dB quieter
at -143 dBm.
The real shocker is when I point the antenna at the two TV towers near
Lexington. The base line goes up to -126 dBm. Heading is 245. The South
Pacific and the Southern sections of the West coast will have to be strong
to be heard!
Last night I worked CO and KS with Q5 signals. The strength was only S5 at
best. Then I worked a fellow in Richmond, KY which is 25 miles from me. I
was able to get a reading on F/B on the antenna and it was 30 dB or better,
just what the model said it would be. I can see Richmond from my tower
(and from the ground when the leaves are off). So It was a pretty good
line of sight path.
So that is my story. Any comments are welcome, especially those which
might point out errors in my thinking or technique.
It was a fun day in the antenna field.
73,
Dave, K4TO
Dave,
What is a 'P3' and how are you connecting it to what and how are
you using it?
Thanks,
Dana
On Sun, Jul 12, 2020 at 8:10 AM Dave Sublette via mvus-list <
mvus-list@lists.febo.com> wrote:
Good morning,
A few days ago I sparked a very good discussion on whether or not I might
need a preamp at the antenna when I got my six meter yagi up. It is up.
It is a 6 element LFA with a 22 foot 9 inch boom length. It is based on
the design by G0KSC. The SWR is 1.0:1 at 50.125 and less than 1.3:1 from 50
to 50.7 MHz.
I use the K3s, KPA500, and KAT500(when necessary). I also have the P3,
which is a very good measuring tool for signal levels, noise baseline,
etc...
The K3s has two preamps built it. I took base line noise measurements with
and without the preamps, on a dummy load and on the antenna as installed at
the tower. There is 320 feet of feedline between the K3s and the antenna.
260 feet is half inch Andrew superflex and the last 60 feet is new LMR
400. There is an RCS 10 remote antenna selector at the base of the tower.
Here are the results:
The scale on the P3 reads in dB. I think it means dBm. I should read the
manual someday.
On the Dummy load with no preamp: -130 dBm
Dummy load with preamp #1: -135dBm , noise in speaker comes up.
Dummy load with preamp #2: -147 dBm noise in speaker "maybe" a little
higher.
Antenna no preamp: -130 dBm
Antenna preamp #1: -135 dBm noise in speaker up "a little"
Antenna preamp #2: -140 dBm noise in speaker noticeably higher.
I have read various opinions as to how much noise increases when the
antenna is connected indicates whether or not a preamp is needed at the
antenna. I don't know how that relates to using internal preamps. But the
fact that there is no difference in noise with and without the antenna when
there is no internal preamp used makes me wonder. What do you think?
I then rotated the antenna and watched the noise base line. It is apparent
that I do not live in a noise free environment. The noise and birdies are
higher when pointed at my house (250 feet away). There is a really quiet
spot 15 degrees off of my house at 45 degree heading. It is 3 dB quieter
at -143 dBm.
The real shocker is when I point the antenna at the two TV towers near
Lexington. The base line goes up to -126 dBm. Heading is 245. The South
Pacific and the Southern sections of the West coast will have to be strong
to be heard!
Last night I worked CO and KS with Q5 signals. The strength was only S5 at
best. Then I worked a fellow in Richmond, KY which is 25 miles from me. I
was able to get a reading on F/B on the antenna and it was 30 dB or better,
just what the model said it would be. I can see Richmond from my tower
(and from the ground when the leaves are off). So It was a pretty good
line of sight path.
So that is my story. Any comments are welcome, especially those which
might point out errors in my thinking or technique.
It was a fun day in the antenna field.
73,
Dave, K4TO
mvus-list mailing list
mvus-list@lists.febo.com
http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
Good morning Dana,
The P3 is Elecraft's matching panadapter for the K3s. It can see up to +/-
100 KHz of the tuned frequency. Plus it does a wide variety of other
things. It is a very accurate measuring device for signal level and
noise floor, etc.
Dave
On Sun, Jul 12, 2020 at 11:53 AM Dana Whitlow k8yumdoober@gmail.com wrote:
Dave,
What is a 'P3' and how are you connecting it to what and how are
you using it?
Thanks,
Dana
On Sun, Jul 12, 2020 at 8:10 AM Dave Sublette via mvus-list <
mvus-list@lists.febo.com> wrote:
Good morning,
A few days ago I sparked a very good discussion on whether or not I might
need a preamp at the antenna when I got my six meter yagi up. It is up.
It is a 6 element LFA with a 22 foot 9 inch boom length. It is based on
the design by G0KSC. The SWR is 1.0:1 at 50.125 and less than 1.3:1 from
50
to 50.7 MHz.
I use the K3s, KPA500, and KAT500(when necessary). I also have the P3,
which is a very good measuring tool for signal levels, noise baseline,
etc...
The K3s has two preamps built it. I took base line noise measurements
with
and without the preamps, on a dummy load and on the antenna as installed
at
the tower. There is 320 feet of feedline between the K3s and the antenna.
260 feet is half inch Andrew superflex and the last 60 feet is new LMR
400. There is an RCS 10 remote antenna selector at the base of the tower.
Here are the results:
The scale on the P3 reads in dB. I think it means dBm. I should read the
manual someday.
On the Dummy load with no preamp: -130 dBm
Dummy load with preamp #1: -135dBm , noise in speaker comes up.
Dummy load with preamp #2: -147 dBm noise in speaker "maybe" a little
higher.
Antenna no preamp: -130 dBm
Antenna preamp #1: -135 dBm noise in speaker up "a little"
Antenna preamp #2: -140 dBm noise in speaker noticeably higher.
I have read various opinions as to how much noise increases when the
antenna is connected indicates whether or not a preamp is needed at the
antenna. I don't know how that relates to using internal preamps. But
the
fact that there is no difference in noise with and without the antenna
when
there is no internal preamp used makes me wonder. What do you think?
I then rotated the antenna and watched the noise base line. It is
apparent
that I do not live in a noise free environment. The noise and birdies are
higher when pointed at my house (250 feet away). There is a really quiet
spot 15 degrees off of my house at 45 degree heading. It is 3 dB quieter
at -143 dBm.
The real shocker is when I point the antenna at the two TV towers near
Lexington. The base line goes up to -126 dBm. Heading is 245. The South
Pacific and the Southern sections of the West coast will have to be strong
to be heard!
Last night I worked CO and KS with Q5 signals. The strength was only S5
at
best. Then I worked a fellow in Richmond, KY which is 25 miles from me.
I
was able to get a reading on F/B on the antenna and it was 30 dB or
better,
just what the model said it would be. I can see Richmond from my tower
(and from the ground when the leaves are off). So It was a pretty good
line of sight path.
So that is my story. Any comments are welcome, especially those which
might point out errors in my thinking or technique.
It was a fun day in the antenna field.
73,
Dave, K4TO
mvus-list mailing list
mvus-list@lists.febo.com
http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
HI Dave, interesting data that you took. I always skip to the bottom line and just see how much the noise comes up when you connect the antenna to the radio compared to a 50 ohm load. So if you are seeing a 7 dB increase in noise with the antenna compared to 50 ohm resistor, and the audible noise is noticeably louder, then I would say that you have a low enough noise figure. No improvement really if you were to add a preamp at the antenna or at the radio. BUT, if you are getting quieter in some other direction, then maybe a preamp would help.
Do you have the 10M/6M optional preamp in the K3S ? If not, I would get one. It makes a substantial improvement. If you do have that preamp, then not much improvement to add at the radio end but you could make up for feedline loss by putting one at the antenna. Your feedline loss should be fairly low so you are likely in good shape if you have the low noise preamp option in the K3S.
73
Steve
K8DZ
On Jul 12, 2020, at 11:59 AM, Dave Sublette via mvus-list mvus-list@lists.febo.com wrote:
Good morning Dana,
The P3 is Elecraft's matching panadapter for the K3s. It can see up to +/-
100 KHz of the tuned frequency. Plus it does a wide variety of other
things. It is a very accurate measuring device for signal level and
noise floor, etc.
Dave
On Sun, Jul 12, 2020 at 11:53 AM Dana Whitlow k8yumdoober@gmail.com wrote:
Dave,
What is a 'P3' and how are you connecting it to what and how are
you using it?
Thanks,
Dana
On Sun, Jul 12, 2020 at 8:10 AM Dave Sublette via mvus-list <
mvus-list@lists.febo.com> wrote:
Good morning,
A few days ago I sparked a very good discussion on whether or not I might
need a preamp at the antenna when I got my six meter yagi up. It is up.
It is a 6 element LFA with a 22 foot 9 inch boom length. It is based on
the design by G0KSC. The SWR is 1.0:1 at 50.125 and less than 1.3:1 from
50
to 50.7 MHz.
I use the K3s, KPA500, and KAT500(when necessary). I also have the P3,
which is a very good measuring tool for signal levels, noise baseline,
etc...
The K3s has two preamps built it. I took base line noise measurements
with
and without the preamps, on a dummy load and on the antenna as installed
at
the tower. There is 320 feet of feedline between the K3s and the antenna.
260 feet is half inch Andrew superflex and the last 60 feet is new LMR
400. There is an RCS 10 remote antenna selector at the base of the tower.
Here are the results:
The scale on the P3 reads in dB. I think it means dBm. I should read the
manual someday.
On the Dummy load with no preamp: -130 dBm
Dummy load with preamp #1: -135dBm , noise in speaker comes up.
Dummy load with preamp #2: -147 dBm noise in speaker "maybe" a little
higher.
Antenna no preamp: -130 dBm
Antenna preamp #1: -135 dBm noise in speaker up "a little"
Antenna preamp #2: -140 dBm noise in speaker noticeably higher.
I have read various opinions as to how much noise increases when the
antenna is connected indicates whether or not a preamp is needed at the
antenna. I don't know how that relates to using internal preamps. But
the
fact that there is no difference in noise with and without the antenna
when
there is no internal preamp used makes me wonder. What do you think?
I then rotated the antenna and watched the noise base line. It is
apparent
that I do not live in a noise free environment. The noise and birdies are
higher when pointed at my house (250 feet away). There is a really quiet
spot 15 degrees off of my house at 45 degree heading. It is 3 dB quieter
at -143 dBm.
The real shocker is when I point the antenna at the two TV towers near
Lexington. The base line goes up to -126 dBm. Heading is 245. The South
Pacific and the Southern sections of the West coast will have to be strong
to be heard!
Last night I worked CO and KS with Q5 signals. The strength was only S5
at
best. Then I worked a fellow in Richmond, KY which is 25 miles from me.
I
was able to get a reading on F/B on the antenna and it was 30 dB or
better,
just what the model said it would be. I can see Richmond from my tower
(and from the ground when the leaves are off). So It was a pretty good
line of sight path.
So that is my story. Any comments are welcome, especially those which
might point out errors in my thinking or technique.
It was a fun day in the antenna field.
73,
Dave, K4TO
mvus-list mailing list
mvus-list@lists.febo.com
http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
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Yes Steve, There are two preamps in my K3s. I may select either one. The
antenna is new, the radio is relatively new, and I am newly back on six
meters after a long absence. I am just trying to learn and make sure I
have everything set up properly. I agree with you. I think the 7 dB
increase indicates I have a low enough feedline loss and system noise
figure to get the best results.
73,
Dave, K4TO
On Sun, Jul 12, 2020 at 4:39 PM Steve Koogler k8dzsteve@gmail.com wrote:
HI Dave, interesting data that you took. I always skip to the bottom line
and just see how much the noise comes up when you connect the antenna to
the radio compared to a 50 ohm load. So if you are seeing a 7 dB increase
in noise with the antenna compared to 50 ohm resistor, and the audible
noise is noticeably louder, then I would say that you have a low enough
noise figure. No improvement really if you were to add a preamp at the
antenna or at the radio. BUT, if you are getting quieter in some other
direction, then maybe a preamp would help.
Do you have the 10M/6M optional preamp in the K3S ? If not, I would get
one. It makes a substantial improvement. If you do have that preamp, then
not much improvement to add at the radio end but you could make up for
feedline loss by putting one at the antenna. Your feedline loss should be
fairly low so you are likely in good shape if you have the low noise preamp
option in the K3S.
73
Steve
K8DZ
On Jul 12, 2020, at 11:59 AM, Dave Sublette via mvus-list <
mvus-list@lists.febo.com> wrote:
Good morning Dana,
The P3 is Elecraft's matching panadapter for the K3s. It can see up to +/-
100 KHz of the tuned frequency. Plus it does a wide variety of other
things. It is a very accurate measuring device for signal level and
noise floor, etc.
Dave
On Sun, Jul 12, 2020 at 11:53 AM Dana Whitlow k8yumdoober@gmail.com
wrote:
Dave,
What is a 'P3' and how are you connecting it to what and how are
you using it?
Thanks,
Dana
On Sun, Jul 12, 2020 at 8:10 AM Dave Sublette via mvus-list <
mvus-list@lists.febo.com> wrote:
Good morning,
A few days ago I sparked a very good discussion on whether or not I might
need a preamp at the antenna when I got my six meter yagi up. It is up.
It is a 6 element LFA with a 22 foot 9 inch boom length. It is based on
the design by G0KSC. The SWR is 1.0:1 at 50.125 and less than 1.3:1 from
50
to 50.7 MHz.
I use the K3s, KPA500, and KAT500(when necessary). I also have the P3,
which is a very good measuring tool for signal levels, noise baseline,
etc...
The K3s has two preamps built it. I took base line noise measurements
with
and without the preamps, on a dummy load and on the antenna as installed
at
the tower. There is 320 feet of feedline between the K3s and the antenna.
260 feet is half inch Andrew superflex and the last 60 feet is new LMR
400. There is an RCS 10 remote antenna selector at the base of the tower.
Here are the results:
The scale on the P3 reads in dB. I think it means dBm. I should read the
manual someday.
On the Dummy load with no preamp: -130 dBm
Dummy load with preamp #1: -135dBm , noise in speaker comes up.
Dummy load with preamp #2: -147 dBm noise in speaker "maybe" a little
higher.
Antenna no preamp: -130 dBm
Antenna preamp #1: -135 dBm noise in speaker up "a little"
Antenna preamp #2: -140 dBm noise in speaker noticeably higher.
I have read various opinions as to how much noise increases when the
antenna is connected indicates whether or not a preamp is needed at the
antenna. I don't know how that relates to using internal preamps. But
the
fact that there is no difference in noise with and without the antenna
when
there is no internal preamp used makes me wonder. What do you think?
I then rotated the antenna and watched the noise base line. It is
apparent
that I do not live in a noise free environment. The noise and birdies are
higher when pointed at my house (250 feet away). There is a really quiet
spot 15 degrees off of my house at 45 degree heading. It is 3 dB quieter
at -143 dBm.
The real shocker is when I point the antenna at the two TV towers near
Lexington. The base line goes up to -126 dBm. Heading is 245. The South
Pacific and the Southern sections of the West coast will have to be strong
to be heard!
Last night I worked CO and KS with Q5 signals. The strength was only S5
at
best. Then I worked a fellow in Richmond, KY which is 25 miles from me.
I
was able to get a reading on F/B on the antenna and it was 30 dB or
better,
just what the model said it would be. I can see Richmond from my tower
(and from the ground when the leaves are off). So It was a pretty good
line of sight path.
So that is my story. Any comments are welcome, especially those which
might point out errors in my thinking or technique.
It was a fun day in the antenna field.
73,
Dave, K4TO
mvus-list mailing list
mvus-list@lists.febo.com
http://lists.febo.com/mailman/listinfo/mvus-list_lists.febo.com
mvus-list mailing list
mvus-list@lists.febo.com
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