Pages: 1 [2] 3 4   Go Down

Author Topic: Options for mounting a small 2 meter Yagi  (Read 532 times)

K1VSK

  • Member
  • Posts: 1949
Re: Options for mounting a small 2 meter Yagi
« Reply #15 on: July 24, 2022, 01:11:04 PM »

This 3 element yagi - 43" boom:  https://www.dxengineering.com/parts/hgn-vb23fm

I wonder if this would help bring in my signal enough better than my existing vertical to make the cost and effort worthwhile.  I would paint it in non-metallic shingle color to stealth it as much as possible.

If there are smaller 2 meter yagis that would be at least as effective as this, please advise.

A 3element beam is around 6dBd gain over a vertical. What that would “buy” you in terms of repeater coverage can’t be discerned. It took my 11element beam to reach some repeaters not close by. Seems like a lot of machination and hypothesizing all for nothing if you can’t ‘get away’ with it which is why I suggested asking.
Logged

KK4GMU

  • Member
  • Posts: 366
Re: Options for mounting a small 2 meter Yagi
« Reply #16 on: July 24, 2022, 01:49:27 PM »

This 3 element yagi - 43" boom:  https://www.dxengineering.com/parts/hgn-vb23fm

I wonder if this would help bring in my signal enough better than my existing vertical to make the cost and effort worthwhile.  I would paint it in non-metallic shingle color to stealth it as much as possible.

If there are smaller 2 meter yagis that would be at least as effective as this, please advise.

A 3element beam is around 6dBd gain over a vertical. What that would “buy” you in terms of repeater coverage can’t be discerned. It took my 11element beam to reach some repeaters not close by. Seems like a lot of machination and hypothesizing all for nothing if you can’t ‘get away’ with it which is why I suggested asking.
What distance do you consider "not close by?"
None of the repeaters I am interested in are more than 20 miles away...most within 15 miles on relatively flat terrain.

And something to keep in mind:  Not all HOAs are the same.  Not all enforce the same. Not all are as restrictive as others.
« Last Edit: July 24, 2022, 01:54:46 PM by KK4GMU »
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

AA4PB

  • Member
  • Posts: 15504
Re: Options for mounting a small 2 meter Yagi
« Reply #17 on: July 24, 2022, 02:29:55 PM »

Unless the repeater uses separate tx and rx antennas, it should have the same lobes on tx as it does on rx. Unless you are running a lot more power than the repeater then you should hear it as well as it hears you. It's possible that your omni-directional vertical antenna is picking up local noise from other directions and that is making the signal sound weaker (i.e. poor signal to noise ratio). A small directional antenna might help reduce the local noise.
Logged
Bob  AA4PB
Garrisonville, VA

K1VSK

  • Member
  • Posts: 1949
Re: Options for mounting a small 2 meter Yagi
« Reply #18 on: July 24, 2022, 02:51:58 PM »


What distance do you consider "not close by?"
None of the repeaters I am interested in are more than 20 miles away...most within 15 miles on relatively flat terrain.
That would be “not close by”

Quote
And something to keep in mind:  Not all HOAs are the same.  Not all enforce the same. Not all are as restrictive as others.

That is stating the obvious. The fundamental question applies regardless about seeking approval or a waiver. Shall we assume the lack of answer is an act of commission?

Living in an apartment/condo has its inherent limitations and consideration for neighbors unrelated to whether or not there are HOA CC&Rs.
« Last Edit: July 24, 2022, 02:59:39 PM by K1VSK »
Logged

KK4GMU

  • Member
  • Posts: 366
Re: Options for mounting a small 2 meter Yagi
« Reply #19 on: July 24, 2022, 03:40:22 PM »


Living in an apartment/condo has its inherent limitations and consideration for neighbors unrelated to whether or not there are HOA CC&Rs.

Exactly right.  Having a sense of moderation and sensitivity so as not to provoke or impinge on the rights of the neighbors is my highest priority. Legalism's purpose is to reign in the inconsiderate.
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

WB6BYU

  • Member
  • Posts: 20896
    • Practical Antennas
Re: Options for mounting a small 2 meter Yagi
« Reply #20 on: July 24, 2022, 09:18:16 PM »

Quote from: KK4GMU

On one repeater frequency at my QTH, the noise over-rides the signal. 




What is the signal strength on your S-meter?

It is quite possible possible that you have a local noise
source that is covering up the repeater signal.

If the signal is full scale, that is likely the case.  Then
you need to eliminate the interfering signal.  It might
be a wall wart or other piece of electronic equipment in
your house.

If the signal strength is below half scale, then it could
be a weak signal from the repeater.


Does the signal strength or readability change with the
modulation on your received signal?

That is a sign of “multi-path”, where the signal arrives
at your location via two different paths, at about the
same strength.  Depending on the path lengths, they
might be in phase (so they add), out of phase (so they
cancel each other), or somewhere in between.

And, yes, that changes with frequency, so it can be
different for the transmit and receive frequencies.

In that case, moving your antenna a foot or two
in any direction can totally change things.  At one
traffic light on my commute, moving the car about 3 feet
was enough to change from “transmit but no receive”
to “receive but no transmit”, and I had to carefully
find a point in the middle where both worked when
I was stopped there.


Using a beam may change the relative signal strength
of the two paths, so they don’t cancel each other as
much.




Quote

...All other repeaters, even further away are fine...




Distance depends on a lot of factors, including local
blockages, antenna height, etc.

How low can you set your transmitter power and still
have a good signal into the repeater?

If the repeater is hearing you just fine, especially on
low power, then higher antenna gain may not be
the answer.


Quote



1)  Keep my vertical, plus install the yagi below it, run a SEPARATE cable to the shack and switch between the two in the shack.  The yagi would remain stationary pointed at that useless SOB repeater.

...
Your thoughts.



I’ve used fixed yagis in the attic in other situations
where I needed more gain for one particular repeater,
and it worked well.  Home brew beams (yagis or quads)
are cheap to build (especially if they don’t need to
survive bad weather).

If you want to test whether a beam will help, you can
build a cheap one and try it temporarily while standing
on the roof, which shouldn’t be an issue for the HOA.
That will tell you whether it is worth pursuing.  You
can also see how much difference it makes when you
move the antenna a foot or two.  (And we can provide
designs for simple beams if you want.)


But the important first step is to analyze the symptoms,
particularly the received signal strength, to figure out
why you aren’t hearing the repeater well, because
without that information, we’re just guessing at what
how to fix the problem.

G4AON

  • Member
  • Posts: 2178
Re: Options for mounting a small 2 meter Yagi
« Reply #21 on: July 25, 2022, 01:27:14 AM »

On one repeater frequency at my QTH, the noise over-rides the signal.  All other repeaters, even further away are fine

Is there a spurious signal on that repeater frequency? You can easily check with your RSP DX SDR. It is also possible the repeater has a fault resulting in weak transmit. Can you listen to it from a car away from your QTH?

If you really want to try a vertical yagi, it should help but at a cost and with possible hassle from your HOA. That antenna you link to only has a short length of boom behind the reflector, commercial yagi antennas for vertical mounting usually have a longer rear boom. This avoids the mast and feeder interfering with the radiation pattern, the hy-gain yagi places the reflector very close to the mounting mast. See this link for a typical commercial example.

http://www.radiostructures.com/antennas/yagi-antenna-vhf-300mhz/vhf3-three-element-vhf-yagi-frequency-range-70-227mhz/prod_167.html

73 Dave
Logged

W9IQ

  • Member
  • Posts: 8866
Re: Options for mounting a small 2 meter Yagi
« Reply #22 on: July 25, 2022, 03:35:36 AM »

Has something changed? On another thread you said:

My S meter reads S9 at 145.330 Mhz, the repeater frequency.  The lowest reading across the whole 2 meter band (144 to 148) is S9.

Or is it that the other repeaters overcome the S9 noise but this particular repeater does not?

- Glenn W9IQ
Logged
- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KK4GMU

  • Member
  • Posts: 366
Re: Options for mounting a small 2 meter Yagi
« Reply #23 on: July 25, 2022, 02:03:59 PM »

Has something changed? On another thread you said:

My S meter reads S9 at 145.330 Mhz, the repeater frequency.  The lowest reading across the whole 2 meter band (144 to 148) is S9.

Or is it that the other repeaters overcome the S9 noise but this particular repeater does not?

- Glenn W9IQ

Well, Glenn, I'm glad you noticed and asked.

I am aware of the differences in S reading between the 7100's Pre-Amp being on and off and the setting of the Filter at  1, 2, or 3.  Currently when the Pre-Amp is "on" and Filter set at 1 (wider bandwidth), the S meter reads 8.5, to very close to 9.  In the other extreme, when the Pre-Amp is "off" and the Filter is set at 3 (narrower bandwidth), the S meter reads 2.

I haven't yet changed those two settings when receiving signals on the 145.330 frequency repeater.  But I will within the next few days.  If I recall, the last net call in we had, the Pre-Amp was off, but the Readability was still between 1 and 2.  I will pay more attention to those settings and change them during my next RX on that repeater.

Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

WA3SKN

  • Member
  • Posts: 8126
Re: Options for mounting a small 2 meter Yagi
« Reply #24 on: July 25, 2022, 02:45:39 PM »

A 3-5 element 2m beam (expect 3-6 ft boom length) will more than meet your needs.
Will that be "stealthy" enough? Do you want to build it?

-Mike.
Logged

WB6BYU

  • Member
  • Posts: 20896
    • Practical Antennas
Re: Options for mounting a small 2 meter Yagi
« Reply #25 on: July 25, 2022, 02:46:59 PM »

My question would be, what is the S-meter reading on that channel
when the repeater is not transmitting, compared to when it is.

And for the other channels you can hear as well.

That gives us an idea of whether the problem is a weak signal
from the repeater, or a stronger local signal that is interfering
on that frequency.

And is "S-9" the top of the meter scale?

KK4GMU

  • Member
  • Posts: 366
Re: Options for mounting a small 2 meter Yagi
« Reply #26 on: July 25, 2022, 03:48:27 PM »

The S meter reads 2 when the repeater is NOT transmitting.  It reads 3.5 when it IS transmitting.  The meter on my 7100 goes up to 60.

On the RSP/SDR (for some  reason I cannot post the screen shot now) there is a narrow (maybe 5 MHz wide) spike at 145.320 from the noise base of 137dBm to 130dBm.  I'm not sure how significant that is.
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

KK4GMU

  • Member
  • Posts: 366
Re: Options for mounting a small 2 meter Yagi
« Reply #27 on: July 25, 2022, 03:59:55 PM »

A 3-5 element 2m beam (expect 3-6 ft boom length) will more than meet your needs.
Will that be "stealthy" enough? Do you want to build it?

-Mike.
Not yet. Is that 3 feet to 6 feet, or 3' 6" boom length?  I'm now thinking that even 3' may be a problem for my neighbors and/or the HOA if placed a few feet above my roof on a mast - unless it could be laid on top of my asphalt shingles.  But then I understand there is likely some degree of loss from the shingles.  How far above the shingles should such antenna be to avoid significant loss:  an inch?  a foot?  More?

I have a radio test on that repeater tomorrow with another area ham.  I want to experiment more with radio settings first.
Logged
IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

K1KIM

  • Member
  • Posts: 1556
    • HomeURL
Re: Options for mounting a small 2 meter Yagi
« Reply #28 on: July 26, 2022, 07:46:46 AM »

This 3 element yagi - 43" boom:  https://www.dxengineering.com/parts/hgn-vb23fm

I wonder if this would help bring in my signal enough better than my existing vertical to make the cost and effort worthwhile.  I would paint it in non-metallic shingle color to stealth it as much as possible.

If there are smaller 2 meter yagis that would be at least as effective as this, please advise.

By design, you can't get any smaller and have 3 elements based on spacing of the reflector, driver and director. Element length is element length based on the band.

There are dozens of manufacturers, but they all have the same dimensions (within reason) whether it be a hairpin or gamma match tuning.

You can play around with NEC and see.
« Last Edit: July 26, 2022, 07:52:00 AM by K1KIM »
Logged
So Many Toys.......So Little Time!

AF5CC

  • Posts: 1664
    • HomeURL
Re: Options for mounting a small 2 meter Yagi
« Reply #29 on: July 26, 2022, 10:14:47 AM »

Laying it on top of the shingles would be laying it flat on the roof, correct? That would give you horizontal polarization, whereas the repeater is using vertical polarization.  The cross-polarization loss would be 20db or so, cancelling out any advantage of the beam.  If you really needed something that had to lay on the roof, you could try a 2 meter quad, and feet it halfway up one of the vertical sides of the element, which should give you vertical polarization.

73 John AF5CC
Logged
Pages: 1 [2] 3 4   Go Up