Antenna Work on Wilk Roof

[Jeffrey Olson]

Hello everyone!

I hope your springs are going great.  This Tuesday we have some work that we will be doing on the roof of the Wilkinson Center and invite those who are interested to come help.  The rotors for the satellite antenna have been rumored to have taken a lightening strike and nobody knows if they work or not.  We will take them down so that we can examine their condition.  We will be meeting at the shack at 7:00 pm this Tuesday.  We hope to see you there.

Jeff Olson

KG6MJH

BYU Amateur Radio Club President

jef...@sbcglobal.net

[Tanner Thompson]

Update on the antenna work:

We met tonight and took down all the satellite antennas and the two
rotors. The rotors are in the shack; we'll be testing those next
week. Should one or both of them prove to be broken, we'll have an
empty antenna mount or two; one idea is to move the 2 meter repeater
antennas to these mounts to make them more serviceable. If you have
any other fun ideas about what to put up, don't be afraid to throw
them around.

Looking down the road, we have quite a lot of other antenna work that
we'd like to get done soon while the weather's nice, especially by the
beginning of Fall so we can have the shack more usable to generate
interest (and work some good DX :) once Fall semester starts. This
includes assessing and fixing the HF triband beam, which is at the
very top of the tower. We don't have schedule specifics yet, but it's
good to have it on your radar since it will likely be a big club-wide
undertaking.

Until next time,

Tanner
VP, BYUARC
KC9JOC (@gmail)

> jeff...@sbcglobal.net

[Brent Smith]

Just a follow up on the rotor removal last night.
We will not be able to leave the antenna, on the floor, were they are
for very long.
Jim and I talked and believe that we need to get the rotors mounted so
we can get the antenna back out or the mechanical room even if the
rotors don,t work. We plan to do that remounting next Tuesday at 7:00.
So come have some fun next Tuesday.
That also means that we need to get the rotors tested before then. I
volunteered to do that testing but if anyone wants to help give me a
holler. (N7TOT BYU 2M repeater).

Brent Smith
N7TOT

[Brent Smith]

Well we have very good news about the satellite rotors.
When I say we, I mean Dee and I.
We spent close to 3 hours on Thursday night testing and tweaking the two
rotor assemblies.
We found that everything works. There are a few lost screws we will have
to replace. And a few loose screws and wires which have been tightened
up. They are reassembled and ready to go back on the roof on Tuesday.
We should replace one of the control cables before final deployment.

Now for the bad news.
Some time in the last 2-3 days the rotor on the tri-band beam developed
a problem.
It will turn clockwise but not counter clockwise. I am guessing that it
is just a loose wire some where, but I have not had time to look into it.

My thanks to Dee for the help, it is always more fun to work in a team.

Brent Smith
N7TOT

[Brent Smith]

 

I did a bit more testing on the tri beam rotor Friday night before I
went home. 

The rotor actually turns CCW its just the direction meter
that is not working. 

Brent 

N7TOT 

 

 

[Brent Smith]

Sorry but this is going to be a bit long.

As most of you know, all of the antenna on the roof of the Wilk need some work.

Jim has an antenna analyzer which he has used to check all of the antenna we have up.

All of the antenna need to have their coax replaced and some of the antennas need to be replaced.

We really can't tell if the antenna are good or bad until the coax has been replaced.

The following is the list of antenna assets we have.

1. The Diamond VHF/UHF high gain on the very top of the tower, connected to the Yaesu mobile.

2. The tri-band beam HF, with rotor, connected to the HF rig.

3. A 40 meter inverted V only half deployed, connected to the HF rig.

4. A new 40/80m inverted V, in the shack.

5. The 2m high gain repeater receive.

6. The 2m high gain repeater transmit.

7. The 70cm high gain repeater transmit/receive.

8. A home made high gain VHF/UHF J pole.

9. 2 azimuth/elevation rotors assemblies.

10. 2 2m circular satellite antenna.

11. 2 23 cm circular satellite antenna.

12. 70cm circular satellite antenna.

13. The main tower.

14. The East Ibeam mast.

15. The West Ibeam mast.

Part of the challenge of the working on the antenna is that all of the functioning antenna are on the tower, which means that when we want to work on anything we have to work on everything.

Jim (N7XGA) has mentioned on several occasions that it would be a good idea to move some of the antennas off of the tower on to one of the masts.

 

So here is my proposal for the new antenna/tower/mast configuration as we work on things this year.

Comments Please.

1. Bring up one set of satellite antenna on the East Ibeam mast. This would consist of a rotor, 2m circular, 70cm circular and 23cm circular antenna.

2. Change the top of the West Ibeam to a T bar on the top and then mount 4 antenna on it. 2 above the T and 2 below the T. These would be the 2m repeater transmit, the 2m repeater receive, the diamond and the J pole

3. Mount the 70cm repeater antenna on the very top of the tower with the tri-band beam just below and the 40m/80m inverted V underneath.

As part of this I would suggest that we buy 3 new antenna to replace the 70cm repeater, 2m repeater transmit and 2m repeater receive.

Comments Please.

Does this sound acceptable?

Does this sound reasonable?

Does this sound doable?

Alternate suggestions?

Comments Please!

 

Brent Smith

N7TOT

 

 

 

 

[Brent Smith]

I went in again to check the meter on the try-band beam and found that
it now works.
I checked for loose wires and found none, either in the shack or in the
penthouse.
I am guessing that this means that we have a problem with the rain
shorting out the electronics for the meter, up on the tower.
Yet another reason to get the maintenance work done up on the tower.

Brent Smith
N7TOT

[Brent Smith]

Taking into account Jim's suggestion, we would have.

1. One set of satellite antenna on the East Ibeam mast. This would

consist of a rotor, 2m circular, 70cm circular and 23cm circular antenna.

2. Change the top of the West Ibeam to a T bar on the top and then

mount 2 antenna on it above the T . These would be the 2m/70cm diamond

and the J pole

3. Mount the 70cm repeater antenna on the very top of the tower with the

tri-band beam just below and the 40m/80m inverted V underneath. And the
2m repeater receive/transmit antennas at the top of the fixed portion of
the tower.

Prices of new antenna?
There are a lot of people that make antenna. We could make our own, but
I would suggest that we do not do this for the repeaters. Some of the
bigger names seam to be Diamond and MFJ.
There are lots of options: steel with fiberglass, aluminum, monoband,
dual band, various gain.
Diamond says their best repeater antenna is the X510HDM, 2m/70cm, gain
2m-8.3dB/70cm-11.7dB, 250 watts, wind rating 90MPH(no ice), height 17.8
ft., fiberglass radome, steel radials and mounting hardware, Type UHF
cable connection, pre tuned. Three piece antenna.
HRO price $199.95 or with N connector $219.95

MFJ makes what looks to be about the same antenna. Two piece antenna.
2in shorter, 200 watts. same gain.
MFJ-1526 $149.95( UHF connector)
MFJ-1526N $149.95(N connector)

Brent
N7TOT

[Jim Manookin]

What would you think of combining the 70cm TX/RX and 2m RX into one antenna, with a diplexer, and using a separate 2m only antenna for 2m TX?

That would eliminate the flex cable (and possible cable breakdown from repeated flexing, plus the extra connectors) to get past the HF beam rotator. It would also save the cost of one antenna, and reduce the cable count on the tower.

I looked at the Diamond X510 and it may be too long for our tower - at over 17 ft, it is nearly the same length as the main tower section, which leaves no safety margin for head clearance (or snow buildup on the roof, for that matter). I wonder if a better choice might be the X300A (for 2m RX/70cm TX/RX) and F22A (2m TX) - we sacrifice not quite 2dB of antenna gain, but achieve head safety clearance.

On the West pipe mast, I would propose mounting the antennas opposite each other - one above the yardarm and the other below - to increase the RF separation/isolation between them. The yardarm can extend on both sides of the pipe mast, to allow accommodating future antennas in other bands.

Jim Manookin
BYU Office of IT
Design Engineer
BYUARC Advisor
2306A ITB
Voice: 801 422 7547
Fax: 801 422 0767
Email: jim_ma...@byu.edu
Email: n7...@byu.edu

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[Bryan Peterson]

On Tue, 22 May 2012, Jim Manookin wrote:

> What would you think of combining the 70cm TX/RX and 2m RX into one
> antenna, with a diplexer, and using a separate 2m only antenna for 2m
> TX?

...

> I looked at the Diamond X510 and it may be too long for our tower - at
> over 17 ft, it is nearly the same length as the main tower section,
> which leaves no safety margin for head clearance (or snow buildup on the
> roof, for that matter). I wonder if a better choice might be the X300A
> (for 2m RX/70cm TX/RX) and F22A (2m TX) - we sacrifice not quite 2dB of
> antenna gain, but achieve head safety clearance.

An X300A combined with an F22A would be a good match since they have
nearly the same 2m gain (6.5 dB versus 6.7 dB). They are also very near
the current antennas (7 dB) so not much would change. They are also a
reasonable length (10' and 10.5' versus the current antenna at 9.3'). And
you could probably leave the repeater untouched.

For what it is worth, using N connectors is a lot better than using UHF
connectors outside. Good N connectors seal better (the UHF connector
doesn't seal at all unless you wrap it in some kind of sealant). The
current tower configuration used something like four rolls of coax seal to
try to seal all the connections.

Bryan Peterson
bryan_p...@byu.edu

[Brent Smith]

If we buy a dual band antenna and use it for both repeaters, 70cm
transmit/receive and the 2 meter receive. And mount that on the very
top of the tower. Then mount the 2m transmit just under the inverted V
pointing down. Would that not still give us the needed dB separation
while still giving us the head safety clearance and the greatest gain?
Maybe a couple of dB is not worth the effort?

Brent


On 5/22/2012 12:40 PM, Bryan Peterson wrote:

>
>
>
> On Tue, 22 May 2012, Brent Smith wrote:
>
>> Taking into account Jim's suggestion, we would have.

> ...

>> Diamond says their best repeater antenna is the X510HDM, 2m/70cm,
>> gain 2m-8.3dB/70cm-11.7dB, 250 watts, wind rating 90MPH(no ice),
>> height 17.8 ft., fiberglass radome, steel radials and mounting
>> hardware, Type UHF cable connection, pre tuned. Three piece antenna.
>> HRO price $199.95 or with N connector $219.95
>

> If you purchase a dual band repeater antenna I would suggest that you
> drop the separate 70 cm repeater antenna. However, if you have a
> single antenna for 2m, as would be necessary with a 17.8' antenna (I
> doubt you can safely fit two under the beam), you will need to
> redesign the 2m antenna connections.
>
> There needs to be a minimum of 58 dB of isolation between the
> transmitter and the receiver at the transmitter frequency. That would
> put you on the ragged edge of having the transmitter desense the
> receiver. You also have to make sure that the transmitter output is
> at least -160 dB down at the receiver frequency (i.e., the power at
> the receiver frequency that the receiver gets from the transmitter
> must be less than about 10^(-15) W to avoid having the transmitter
> open the squelch on the receiver).
>
> Currently we have four homemade cavities on the receiver that are
> tuned for 32 dB rejection at 145.33 MHz. That was about all we could
> get out of them. Combined with the antenna separation this gave us
> adequate isolation for the receiver to work properly.
>
> We also had a little trouble with the transmitter wings having enough
> amplitude at 144.73 MHz to open the squelch on the receiver so there
> are three commercial cavities on the transmitter tuned to 31 dB
> rejection at 144.73 MHz. These are the values necessary when the
> repeater changed frequencies in April 1998. The transmitter has been
> worked on at least twice since then. The cavities on the transmitter
> may no longer be necessary but we haven't bothered to check.
>
> Bryan Peterson
> bryan_p...@byu.edu
>

[Brent Smith]

Oh, sorry I see that is what you ment when you said we would have to
redesign the receiver.

Brent

[Brent Smith]

Bryan
Having read your post carefully 3 times now I am going to ask my
question again.
2 dual band antenna. Both X510HDM. One mounted on the very top of the
mast for 70cm transmit and receive and 2m receive. The other mounted
upside down for 2m transmit just below the inverted V. There would be
the yard arm offset.
I assume this would give us the 2m transmit receive isolation we need
and the head space safety.
What do you think?
It is about what we have now with the exception of the yard arm offset.
We could actually test this today by moving the 2m receive to the
present diamond dual band.

I greatly appreciate your thoughts and insight on this issue.

Brent

[Jim Manookin]

One of the motivations for my suggestions was to eliminate the flex cable and its attendant reliability issues from the repeaters operation. If we mount repeater antennas on the top of the tower, we will have flex cable issues like we presently seem to have with the HF beam. It also makes antenna servicing difficult because of tower climbing (read: safety) issues, plus the need to remove the 2m transmit antenna yardarm in order to access the HF beam, inverted-V, and tower-top antenna. But there is no doubt that the tower top is the best place to put a high gain antenna - that alone may boost our repeater range significantly.

One follow-on question that may bear investigation: if we use dual-band antennas, especially high-gain dual-band antennas, for the repeaters, how would the cost of two antennas compare with the cost of improving the tuned cavity isolators for the 2m repeater so that we could use a single TX/RX antenna for both repeaters? Does anyone know? Can we add cans to the present cavity banks, or do we need to replace the cavity banks?

Jim Manookin
BYU Office of IT
Design Engineer
BYUARC Advisor
2306A ITB
Voice: 801 422 7547
Fax: 801 422 0767
Email: jim_ma...@byu.edu
Email: n7...@byu.edu


-----Original Message-----
From: byu...@googlegroups.com [mailto:byu...@googlegroups.com] On Behalf Of Brent Smith

[Bryan Peterson]

I agree with Jim on the flex cable issue. I would not put anything that
is mission critical on top of the beam. You have to put in extra
connections in a place that is rather hard to service. And the
higher-quality cables that are advisable for good performance (low
leakage, etc.) tend to be less flexible. In fact, I think we have a
cheaper cable that connects the feed line on the high-gain antenna to a
better cable that actually goes from the shack to the tower to improve the
flexibility at the beam.

Increased gain on the repeater is actually not a problem unless you
improve the receive antenna. We actually have the power on the
transmitter turned down a little because you could hear the repeater
clearly long before you could actually bring it up (known in the repeater
circles as an alligator - all mouth and no ears).

I really haven't looked at sharing an antenna on the 2m repeater. The
problem is that the separation is so small. I think they usually use a
circulator to improve the separation but I don't remember the designs I
have seen. And I don't know what a circulator would cost. Typical
isolation is something like 20 dB.

Bryan Peterson
bryan_p...@byu.edu

[Bryan Peterson]

I just checked on the price from one vendor for a circulator with 20 dB of
separation for the 2m band. It is $850. But it is in stock, for what
that is worth. The cost of tuned cavities is about $400 or so each. It
is possible that the existing cavities could be tuned a little better.
The are all in pass band configuration and it may be possible to use some
of them in notch configuration to improve the rejection. I'm not sure if
that will work any better since I'm not fully versed in the black magic of
RF engineering. I found one individual who claimed to get 80 dB of
isolation using four cavities. That's significantly higher than we have.
There are also comments about making the cables connecting the cavities
1/4 wavelength. I don't remember doing that when we originally set up the
cavities. That may buy us a little improvement.

I no longer have access to tuning the cavities easily since Scott Daniel
has been kicked out of his area for remodeling and his RF equipment is
scattered hither and yon. It's a tricky process because you have to tune
the cavities while still keeping the SWR low so there are all sorts of
tweaks and adjustments to make them work.

Bryan Peterson
bryan_p...@byu.edu

[Chuck McCown]

I take great delight in reading this thread.

Back in the mid 1980s, I personally built the first BYU repeater using some
junk I got from Scott Daniel. It was based on Motorola HT200 handi talkies.

I hand built the cavity duplexer by using some 6" aluminum irrigation pipe
that one of the club members got from the family farm. We built a low noise
pre-amp from a kit that we got from AES in Las Vegas.

That repeater was killed by lightening. The BYU police department helped us
to buy the second one. We added the first telephone patch to that.
Discrete transistor amplifiers on perf board. I later changed to op amps.

Yep, tuning is critical. 600 kHz separation is a killer on 2 meters. Back
in the day, I made this double angle iron bracket to put on the tip top of
the tower so we could put our ringo ranger repeater antenna up as high as
possible. One single antenna for TX and RX. Quite satisfying when I was
finally able to kerchunk it from I-80 near Grantsville.

Chuck McCown

[Jim Manookin]

Chuck,

Thanks for the delightful walk down memory lane!

I, for one, would be interested in learning more from you about the earlier days of BYUARC - I think it would make an interesting topic for a club meeting.

Thanks for sharing your wisdom!

[Brent Smith]

Last night Jim, Dee and I remounted the satellite rotors and antenna.
Russell checked in on the radio but was unable to join us.
We also discussed the possible next steps to get everything up and running.

Brent
N7TOT

[Brent Smith]

I appreciate everybody that has chimed in and help mold this discussion.

Taking into account several things, I.E. flex of the cables a the the
top of the tower, the challenges of maintaining equipment on the tower
and the challenges of changing the 2m cans/circulators/antenna
configurations. And the fact that Jim has used an antenna analyzer to
measure how well the antenna are working and it is not good. We believe
that all of the coax from the penthouse to the antenna is in need of
replacement, which is where all of this started.

I would now like to propose Version 3.
1. Remove the repeater antenna off of the tower to the West Ibeam mast.
This would involve changing the 2m receive antenna to a dual band high
gain(17 ft) antenna and also using it for the 70cm repeater
transmit/receive. The 2m transmit antenna would be changed to a mid gain
mono band antenna(10ft). The mast would be extended with the addition of
a fiber glass top segment.
Two antenna on the mast.

2. Change the configuration of the tower by eliminating all of the
present yard arms. Leave the Diamond dual band on the top. Next the
tri-band beam. And just under that, replace the 40m inverted V with a
40m/80m inverted V. Finally remount the J pole dual band but mount it
low on the tower so it can be maintained without the need of a ladder or
climbing the tower.

3. On the East Ibeam mast mount the 2m, 70cm and 23 cm satellite antenna
and rotors.

That will leave the following unused extra parts: 2m transmit antenna,
2m receive antenna, 70cm antenna, 2m circular antenna, 23cm circular
antenna and an elevator/azimuth rotor assembly.

Thoughts?
Comments?
Problems?

Brent Smith
N7TOT

[Jim Manookin]

Other than the fact that Version 3 puts the repeater antennas on a lighter-duty mast than they are presently on, I really like this proposal. I am a little concerned for the wind load, as I mentioned last night. But it puts critical services in a much easier-to-service situation.

The copper J-pole, by the way, is not a dual-band unit, but a collinear antenna (i.e. higher gain). It needs some TLC (aka repair) before it should be re-mounted. Mounting it will require either remodeling or replacing a yardarm so it can be cantilevered out from the tower. It might be worthwhile to also mount a 70-cm collinear J-pole (I think we have one in the shack) at the same height on the tower.

As far as unused extra parts are concerned, we could keep the antennas and rotor for repair parts for the satellite system (we would have to dismantle the antennas so we could store the pieces). We could also mount one or more of the high-gain Yagi's on the tower (just above head-height), aimed at some (yet to be identified) distant station(s), for DX terrestrial operation.

Whatever we finally decide on for an antenna farm, we should keep in mind that even though everything will be more serviceable, we need to plan for a minimum of roof time. Physical Plant frowns on too-frequent roof access; it wears out the roof membrane, and risks unintended damage. Abuse of the privilege may result in restriction or loss of it.

Jim Manookin
BYU Office of IT
Design Engineer
BYUARC Advisor
2306A ITB
Voice: 801 422 7547
Fax: 801 422 0767
Email: jim_ma...@byu.edu
Email: n7...@byu.edu


-----Original Message-----
From: byu...@googlegroups.com [mailto:byu...@googlegroups.com] On Behalf Of Brent Smith
Sent: Wednesday, May 23, 2012 1:40 PM
To: Bryan Peterson; 'byu...@googlegroups.com'

[Scott Parker K7LU]

OK, here's some more history....

Back in those days the club was split into a couple of factions that tended to eye each other with a degree of suspicion.

Those of us that gravitated toward the lower end of the spectrum considered that Chuck guy something of an enigma.  On the one hand, we were rather in awe of his technical prowess.  On the other hand, the end product of his efforts seemed to cater to that other faction, the guys that we felt were trying to convert out beloved BYU ARC into the BYU Wireless Intercom Club.

73 DE K7LU

[Brent Smith]

I formally make a motion to the club that we accept proposal #3 for the
antenna farm and authorize the club leadership in consultation with the
club adviser to expend the funds necessary to accomplish it.

Do I have a second?

Brent Smith
N7TOT

[Chris Black]

I'm appreciative that we currently have individuals interested in restoring the antenna farm. About 8 years ago, I was heavily involved in working on those satellite antennas and rotors. We've needed to address the tower issues for quite some time. I realize that I've been rather mute so far on this discussion, I've been extremely busy. However, I am extremely interested in the topic and am willing to help out. My schedule should free up in just a week or so.

Not to be a drag, but I'd like just a little while longer to digest the proposed changes. This entire thread started on Monday with proposal #1 and quickly moved through #2 and finally #3. Is this the best solution? Possibly. I don't want to break the momentum, but would like to make sure that we get the biggest bang for our buck.

Things to be considered:

1. I have an unused, but mounted, commercial 440 antenna available for the club's use. Will it fit into our plans?
2. Should we consider relocating the repeater? Some things have changed around campus and the opportunity to relocate to a higher structure may exist. We should entertain the idea since we are doing major overhaul of the repeaters.
3. Are there additional options or resources that have not been considered?

Again, I'm excited about getting the farm back where it needs to be. I'm willing to help and be involved. I don't want to rain on anyone's parade, but let's take the time to make sure the decision we make is the best one and not rushed.


Chris
KD4AHM

[Brent Smith]

No rain detected. Lets take the time we need but I would like to get it
done before snow flies.

Brent

[Brent Smith]

Last year the roof of the WSC was upgraded. This required the temp
removal of all cables going to the satellite antenna.
We are not allowed to put them back the way they were, laying on the
roof. New access has been provided through pipes on the East and West
side of the penthouse. Also the 70cm repeater seemed to be deaf. And
there seemed to be a weather related SWR problem with the Tri-band
beam. All of these things seemed to indicate that the coax may be in
question. Jim then used an antenna analyzer on all of the functional
antenna. Those graphs are available in the shack in the equipment status
log or I could send them out to the list if needed. Either the antenna
or coax has gone bad or both on all but maybe the dual band Diamond.
Jim and Walter ( the club pres) checked with risk mngt about the safety
of climbing the tower. They are not comfortable with climbing the tower.
But we can use a ladder attached to the tower.
The weather was bad by the time all of that was figured out.
We are now having weather related failures with the direction meter on
the tri- beam as well.

It looks like we need to work on/replace just about all of the
coax/antenna. Thus the proposals.
And the weather is good.

Brent Smith
N7TOT

[Brent Smith]

Dee and I worked on the piles of stuff.
Dee volunteered to ksl/ebay the wall transformers.
A few things were saved. Less then half of a box.

Brent
N7TOT