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Today's Topics:
1. Re: HELP - Hy-Gain TH-3JRS (Bill Cotter)
2. Re: HELP - Hy-Gain TH-3JRS (Tom Hellem)
3. Re: HELP - Hy-Gain TH-3JRS (Tom Hellem)
4. Re: HELP - Hy-Gain TH-3JRS (Gary Mayfield)
5. Re: HELP - Hy-Gain TH-3JRS (Wes)
6. Re: HELP - Hy-Gain TH-3JRS (Charles Tifft)
---------- Forwarded message ----------
From: Bill Cotter <n4lg@qx.net>
To: Gary Mayfield <gary_mayfield@hotmail.com>
Cc: "towertalk@contesting.com" <towertalk@contesting.com>
Bcc:
Date: Sun, 18 May 2025 12:29:38 -0400
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
Gary,
Attached is the manual for the TH-3 MK3 that shows the (grounded)
beta-match dimensions, and the coax choke. I think the hairpin may
be the problem (inductor vs transmission line). I think I would
construct the beta match as designed. It should be easy to make up
from available materials. And, thoroughly inspecting the traps for
electrical integrity and correct location is a must.
73 es GL Bill N4LG
At 09:19 AM 5/18/2025, Gary Mayfield wrote:
Thanks Jim,
We did test with the long coax on the ground, and your
point is well taken about the balun vs a choke. We will take a
fine tooth comb to our hairpin recreation. I suspect that may be
a contributing factor.
73,
Joe n0sd
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of
Jim Brown
Sent: Saturday, May 17, 2025 11:18 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
On 5/17/2025 6:04 PM, Gary Mayfield wrote:
We have also added a balun made from type 31 ferrite material.
Hi Gary,
Don't know anything about that antenna or have a solution for your
problem, BUT -- if that #31 is a lot of turns of transmission line
wound around a 2.4-in o.d. core, it is a Common Mode Choke, NOT a
"balun."
Antennas like yours are designed for specific matching networks or
feeding methods. A choke is used between the transmission line and
that matching system, whatever it is. These matching systems are
often called baluns.
And with respect to your problem and on-the-ground testing -- did
you have a long length of coax on it when testing on the ground,
or just the analyzer connected with a few feet of coax? Their
matching networks often want to be driven by that coax.
Also, study carefully as you can what the original matching system
was.
With gamma and hairpin matching, both the length and the diameter
of the
rod(s) matter.
73, Jim K9YC
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---------- Forwarded message ----------
From: Tom Hellem <tom.hellem@gmail.com>
To: "jim.thom jim.thom@telus.net" <jim.thom@telus.net>
Cc: towertalk@contesting.com
Bcc:
Date: Sun, 18 May 2025 12:25:29 -0600
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
The hairpin match , yes a very good question indeed.
In fact, so good that Hygain didn’t choose to answer it in
their instruction manual. They show all the parts for it, including
what looks like an adjustable shorting bar, but absolutely no
mention of it in the text. DX Engineering is still selling them, with
the exact same manual. What a joke.
Tom K0SN
On Sun, May 18, 2025 at 8:35 AM jim.thom jim.thom@telus.net <
jim.thom@telus.net> wrote:
Date: Sun, 18 May 2025 13:19:54 +0000
From: Gary Mayfield <gary_mayfield@hotmail.com>
To: "towertalk@contesting.com" <towertalk@contesting.com>
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
> We did test with the long coax on the ground, and your point is
well taken about the >balun vs a choke. We will take a fine tooth comb to
our hairpin recreation. I suspect that >may be a contributing factor.
73,
Joe n0sd
How exactly does Hygain manage to get a hairpin to work on 3 bands ???
Typ when you raise the yagi from 8' to top of tower, the resonance
points
will all shift up in freq.
Jim VE7RF
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---------- Forwarded message ----------
From: Tom Hellem <tom.hellem@gmail.com>
To: Bill Cotter <n4lg@qx.net>
Cc: Gary Mayfield <gary_mayfield@hotmail.com>, "towertalk@contesting.com"
<towertalk@contesting.com>
Bcc:
Date: Sun, 18 May 2025 18:42:26 -0600
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
There is no difference between a hairpin match and a beta match, its just 2
different names for the same thing.
My understanding of them is that it's a device for raising the feedpoint Z
of a yagi, typically 25-35 ohms, up to 50 ohms. But when you build one, you
can only adjust its length for one frequency band. I have never seen one
used on a tribander, only on monoband antennas.
Could this be another example of confusion on the part of the folks at MFJ?
Maybe they got tribanders mixed up with monobanders and just stuck a beta
match on the TH-3JR-S because they didn't know any better.
All of the trapped tribanders that I have worked with, and it's been quite
a few, were direct fed with no matching system. The losses in the traps
probably provide the extra Z to arrive at 50 ohms.
It might be worth just removing the beta match altogether and see what
happens.
K0SN
On Sun, May 18, 2025 at 10:33 AM Bill Cotter <n4lg@qx.net> wrote:
Gary,
Attached is the manual for the TH-3 MK3 that shows the (grounded)
beta-match dimensions, and the coax choke. I think the hairpin may
be the problem (inductor vs transmission line). I think I would
construct the beta match as designed. It should be easy to make up
from available materials. And, thoroughly inspecting the traps for
electrical integrity and correct location is a must.
73 es GL Bill N4LG
At 09:19 AM 5/18/2025, Gary Mayfield wrote:
Thanks Jim,
We did test with the long coax on the ground, and your
point is well taken about the balun vs a choke. We will take a
fine tooth comb to our hairpin recreation. I suspect that may be
a contributing factor.
73,
Joe n0sd
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of
Jim Brown
Sent: Saturday, May 17, 2025 11:18 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
On 5/17/2025 6:04 PM, Gary Mayfield wrote:
We have also added a balun made from type 31 ferrite material.
Hi Gary,
Don't know anything about that antenna or have a solution for your
problem, BUT -- if that #31 is a lot of turns of transmission line
wound around a 2.4-in o.d. core, it is a Common Mode Choke, NOT a
"balun."
Antennas like yours are designed for specific matching networks or
feeding methods. A choke is used between the transmission line and
that matching system, whatever it is. These matching systems are
often called baluns.
And with respect to your problem and on-the-ground testing -- did
you have a long length of coax on it when testing on the ground,
or just the analyzer connected with a few feet of coax? Their
matching networks often want to be driven by that coax.
Also, study carefully as you can what the original matching system
was.
With gamma and hairpin matching, both the length and the diameter
of the
rod(s) matter.
73, Jim K9YC
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---------- Forwarded message ----------
From: Gary Mayfield <gary_mayfield@hotmail.com>
To: "'towertalk@contesting.com'" <towertalk@contesting.com>
Cc:
Bcc:
Date: Mon, 19 May 2025 00:46:43 +0000
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
We had a much better day today. We removed the hairpin, and the choke and
fed the antenna with split coax and got the same results as before. --- Has
to be a trap...
The traps all measure as dead shorts at DC (expected), but while measuring
one of the traps with an ohmmeter a sweep of the antenna shows dips (off
frequency) in the SWR (not just flat bad).
We took that trap apart and it looked great, but we did get two tiny drops
of dirty water. It was damp, but not wet. We cleaned it and put it back
together and presto - three nice dips, pretty much on frequency.
We reconnected the hairpin and the in band SWR went from around 3 to 1 in
each band to around 1.2 to 1 on each band (hey it really does help match
the antenna). We added the choke and it didn't have any SWR impact, but we
are quite pleased and Rich's new antenna is on the air. The lift can be
returned in the morning. If you hear Rich ke0epy (originally wn0vzp) on the
air - say howdy!
Thanks to all the folks who provided input. This reflector is a great
sounding board!
73,
Joe n0sd
-----Original Message-----
From: TowerTalk <towertalk-bounces@contesting.com> On Behalf Of Gary
Mayfield
Sent: Saturday, May 17, 2025 8:04 PM
To: 'towertalk@contesting.com' <towertalk@contesting.com>
Subject: [TowerTalk] HELP - Hy-Gain TH-3JRS
Hello - We had a frustrating afternoon today trying to put up a Hy-Gain
TH-3JRS at the QTH of Rich, KE0EPY.
The antenna is previously owned, and we replaced the broken aluminum
matching wire (beta match) with one made of copper. We have also added a
balun made from type 31 ferrite material. Other than that, the antenna
seems to be all original. A few days ago, we tested the antenna on top of
an 8-foot fiberglass ladder, and it had three nice SWR dips right where you
would expect for 20, 15 and 10 meters. Today before taking the antenna up
the tower, we checked it all again, by pointing it lifting it a couple feet
and pointing it straight up. Again, we saw 3 nice dips where they were
expected.
Once we mounted it on the tower the SWR went very high and only showed one
small dip just below 15 meters at 20.8 MHz. Thinking the coax had been
damaged we took a small jumper up in the lift and connected directly to the
balun but got the same results. Then we bypassed the balun - same results.
We removed the beta match and connected straight to the driven element and
got the same results. With the beta match removed the two sides of the
driven element are not shorted to each other or the boom.
We have the lift for another day. Any ideas/thought/suggestions will be
greatly appreciated!!
Thanks, and 73,
Joe - n0sd
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---------- Forwarded message ----------
From: Wes <wes_n7ws@triconet.org>
To: towertalk@contesting.com
Cc:
Bcc:
Date: Mon, 19 May 2025 06:21:13 -0700
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
The beta or hairpin match is an L-network with a shortened driven element
providing the capacitance and the hairpin providing the inductance. It is
not
necessarily a single-band solution.
IIRC, the TH-3, TH-3JR and the TH6DXX all used them.
Wes N7WS
On 5/18/2025 5:42 PM, Tom Hellem wrote:
There is no difference between a hairpin match and a beta match, its
just 2
different names for the same thing.
My understanding of them is that it's a device for raising the
feedpoint Z
of a yagi, typically 25-35 ohms, up to 50 ohms. But when you build one,
you
can only adjust its length for one frequency band. I have never seen one
used on a tribander, only on monoband antennas.
Could this be another example of confusion on the part of the folks at
MFJ?
Maybe they got tribanders mixed up with monobanders and just stuck a beta
match on the TH-3JR-S because they didn't know any better.
All of the trapped tribanders that I have worked with, and it's been
quite
a few, were direct fed with no matching system. The losses in the traps
probably provide the extra Z to arrive at 50 ohms.
It might be worth just removing the beta match altogether and see what
happens.
K0SN
---------- Forwarded message ----------
From: Charles Tifft <chuckw6rd@yahoo.com>
To: Wes <wes_n7ws@triconet.org>
Cc: towertalk@contesting.com
Bcc:
Date: Mon, 19 May 2025 06:29:37 -0700
Subject: Re: [TowerTalk] HELP - Hy-Gain TH-3JRS
Couple Wilson Tribanders too. SYS1 and SYS36 come to mind.
W6RD
On May 19, 2025, at 6:21 AM, Wes <wes_n7ws@triconet.org> wrote:
The beta or hairpin match is an L-network with a shortened driven
element providing the capacitance and the hairpin providing the
inductance. It is not necessarily a single-band solution.
IIRC, the TH-3, TH-3JR and the TH6DXX all used them.
Wes N7WS
On 5/18/2025 5:42 PM, Tom Hellem wrote:
There is no difference between a hairpin match and a beta match, its
just 2
different names for the same thing.
My understanding of them is that it's a device for raising the
feedpoint Z
of a yagi, typically 25-35 ohms, up to 50 ohms. But when you build one,
you
can only adjust its length for one frequency band. I have never seen one
used on a tribander, only on monoband antennas.
Could this be another example of confusion on the part of the folks at
MFJ?
Maybe they got tribanders mixed up with monobanders and just stuck a
beta
match on the TH-3JR-S because they didn't know any better.
All of the trapped tribanders that I have worked with, and it's been
quite
a few, were direct fed with no matching system. The losses in the traps
probably provide the extra Z to arrive at 50 ohms.
It might be worth just removing the beta match altogether and see what
happens.
K0SN
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