Balanced vs. Unbalanced Tuner
 

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of tuner,
but reversed in direction (converting unbalanced to balanced), or need I get
a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced tuner,
will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an unbalanced
(with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160 meter
dipole instead?
Thanks & 73,
Greg, N6GK

I use similar antennas, the ladder line is tied directly to coax with
ferrite beads over the coax to act as a choke balun.

When I used a tuner, I simply used the unbalanced input.

If your intention is to take the ladder line all the way to the tuner, go
with a balanced tuner.

"greg knapp 5" wrote in message
...
I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner,
but reversed in direction (converting unbalanced to balanced), or need I
get
a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner,
will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced
(with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter
dipole instead?
Thanks & 73,
Greg, N6GK

how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

"greg knapp 5" wrote in message
...
I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar
BT1500BAL balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner, but reversed in direction (converting unbalanced to balanced), or
need I get a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner, will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced (with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter dipole instead?
Thanks & 73,
Greg, N6GK

In article ,
Dave wrote:

how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

I've seen three approaches used:

- Asymmetrical (unbalanced) tuner of the T or L or pi configuration,
with a balun at the output. This seems to be the most common
configuration, but is often said to suffer from a degraded balance
or unacceptable losses in the balun when feeding high-Z loads.
It's not easy for a balun to provide adequate choking reactance
when feeding such loads.

- Tuners which use a symmetrical T or L configuration, with the input
to the matching network being fed from the rig/amplifier's 50-ohm
output via a balun. An internal W2DU-type "ferrite beads on coax"
balun seems to be popular in such designs.

- Link-coupled tuners, such as the Johnson Matchbox and the newer
Z-match designs. The input side of the circuit operates unbalanced
and is usually asymmetrical, while the output side (the link) is
balanced with respect to ground. The input and output sides are
coupled inductively. There's sometimes a small amount of imbalance
created by capacitive coupling across the link, but this seems to
be small enough to have little practical effect on the quality of
the balance. In this case, the balanced-to-unbalanced function is
performed by the inductive link, and there's no separate "balun"
component.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

No balun required in a properly designed unbalanced tuner. See the
Johnson Matchbox series.

Dave wrote:

how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

"greg knapp 5" wrote in message
...

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar
BT1500BAL balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner, but reversed in direction (converting unbalanced to balanced), or
need I get a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner, will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced (with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter dipole instead?
Thanks & 73,
Greg, N6GK

Google search for "balanced-balanced " or "Richard Measures" (author of
article).
I built one, it worked great.

On Sun, 24 Jul 2005 11:32:37 -0700, "greg knapp 5"
wrote:

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of tuner,
but reversed in direction (converting unbalanced to balanced), or need I get
a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced tuner,
will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an unbalanced
(with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160 meter
dipole instead?
Thanks & 73,
Greg, N6GK


Have not seen any published tests comparing balanced vs. unbalanced
tuners, so any comparisons will probably be theoretical in nature.
Also, instread of the dx engineering balun, you might look at a
w2du-style balun -- see his article at
http://www.w2du.com/Reflection2.html

bob
k5qwg

"Dave Platt" wrote in message
...
In article ,
Dave wrote:

how does the balanced tuner get from the unbalanced output of the
amplifier
and the balanced feedline? is there not a balun in there somewhere
anyway?

I've seen three approaches used:

- Asymmetrical (unbalanced) tuner of the T or L or pi configuration,
with a balun at the output. This seems to be the most common
configuration, but is often said to suffer from a degraded balance
or unacceptable losses in the balun when feeding high-Z loads.
It's not easy for a balun to provide adequate choking reactance
when feeding such loads.

- Tuners which use a symmetrical T or L configuration, with the input
to the matching network being fed from the rig/amplifier's 50-ohm
output via a balun. An internal W2DU-type "ferrite beads on coax"
balun seems to be popular in such designs.

- Link-coupled tuners, such as the Johnson Matchbox and the newer
Z-match designs. The input side of the circuit operates unbalanced
and is usually asymmetrical, while the output side (the link) is
balanced with respect to ground. The input and output sides are
coupled inductively. There's sometimes a small amount of imbalance
created by capacitive coupling across the link, but this seems to
be small enough to have little practical effect on the quality of
the balance. In this case, the balanced-to-unbalanced function is
performed by the inductive link, and there's no separate "balun"
component.

so, no matter how you spell it, unbalanced in, balanced out, somehow the
tuner either has a component called specifically a balun, or combines it
into other parts that also transform impedance... essentially making the
whole tuner one big balun. no matter how its done somewhere between the
amplifier unbalanced output and the balanced wire there is something doing
the balun function.

Ham op wrote:
No balun required in a properly designed unbalanced tuner. See the
Johnson Matchbox series.

Dave wrote:

how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

"greg knapp 5" wrote in message
...

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar
BT1500BAL balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner, but reversed in direction (converting unbalanced to balanced), or
need I get a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner, will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced (with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter dipole instead?
Thanks & 73,
Greg, N6GK
Hi Ham Op, did you mean no balun required in a properly designed
"balanced tuner"? Are not the Johnson Series balanced tuners?
Gary N4AST

On Sun, 24 Jul 2005 11:32:37 -0700, "greg knapp 5"
wrote:

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.

Is the radiation pattern on all of these bands acceptable/useful?

(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?

Study this before deciding: http://eznec.com/misc/ibalun.txt

Considering the capacitor in the Palstar isn't a balanced design, the
capacitive coupling from it to ground is asymetrical, so I would not
call it a balanced tuner. Also, I don't see anything that looks like
a 1500 W balun in there.

Ten Tec says, "Because there are only two variable components, there
is only one setting of each which will provide a perfect match to a
given load impedance. This unique setting automatically provides the
lowest Q network possible. Low Q means low circulating currents, hence
low loss, and it also provides the widest frequency bandwidth of
operation before retuning is necessary (very useful if you're moving
up and down the SSB portion of the band, for example)..."

They are correct when they say that there is only one setting for a
match, but the L-network Q is set by the load and source Z and is
likewise fixed and totally out of the control of the operator. This
may or may not give the largest operating BW and/or lowest loss.

For example, take a load Z of 5 -j10 at 7 MHz. With capacitor Q =1000
and inductor Q = 250 (good luck with a roller inductor), an L-network
of C = 1364 pF and L =0.568 uH will give SWR = 1.02. The network loss
will be 0.1 dB.

Using the same load Z and component Q, a high-pass-Tee network of Cin
= 1438 pF, L = 0.36 uH and Cout = 3912 pF will give SWR = 1.01 The
network loss will be 0.07 dB.

More parts, lower loss. So much for conventional wisdom. Now this is
a pretty wild load Z, but with certain antenna feedpoint Z and
transmission line lengths and Zo, it's possible. Admittedly, the
differences in insertion loss are negligble but they are different in
the -wrong- direction, thus proving the point.

Of course, try and find a tuner with capacitors of this high a value.

Also, there are some impedances that cannot be matched with either
configuration of a low-pass (series inductor) L-network. The same can
be said for any other topology, but you should be aware of this.

(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of tuner,
but reversed in direction (converting unbalanced to balanced), or need I get
a different tuner?

I wouldn't do this.

(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced tuner,
will the balun waste a ton of RF in heat and loss?

Maybe. In my opinion balun loss is no different from line
attenuation. Line attenuation is magnified by SWR and I see no reason
why balun loss wouldn't be too, particularly since most baluns are
constructed from a transmission line.

(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an unbalanced
(with balun) tuner.

(5) I have plenty of room, would it make any difference if I put a 160 meter
dipole instead?

If you have plenty of room, why limit yourself to one compromise
antenna?

The Johnson Matchbox series are BALANCED tuners. I see my comment was
ambiguous.

wrote:


Ham op wrote:

No balun required in a properly designed unbalanced tuner. See the
Johnson Matchbox series.

Dave wrote:


how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

"greg knapp 5" wrote in message
...


I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar
BT1500BAL balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner, but reversed in direction (converting unbalanced to balanced), or
need I get a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner, will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced (with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter dipole instead?
Thanks & 73,
Greg, N6GK

Hi Ham Op, did you mean no balun required in a properly designed
"balanced tuner"? Are not the Johnson Series balanced tuners?
Gary N4AST

I read the article you cited, looked at the QST article on the 238A (noting
the size of the 3.5 Kv peak capacitor), and looked at the Palstar webpage at
the "inside" shot of the Palstar BT1500BAL (huge capacitor by comparison,
rated at 4.5 KV; but noted it had a ferrite input balun) and also read
W8JI's comparison of balun loss that showed the difference between the
various baluns...with the DX Engineering, coiled coax (20 ft "scrambled"),
and 60-foot "solenoid", coming out the lowest loss, and with the DXE one
being the lowest...but that was at a LOW SWR!

If I had a low SWR on all bands why would I need a tuner? I know it will be
pretty high SWR on some bands, so what then?

I guess that is what MY REAL QUESTION boils down to...although I like the
"single resonant" L-type Ten Tec 238 unbalanced tuner (and it would work
great with my future inverted L), it needs a balun to match it to the open
wire feed. Will the balun, at HIGH SWRs, just burn up my watts in heat and
smoke? Versus, a balanced tuner (Johnson, Palstar), which doesn't need a
balun (just a small one at input, which is at low SWR and negligible loss),
and does not overheat. So what I am wrestling with is which configuration
AND WHY:
(1) 238B to DXE 1:1 current balun to open wire
versus
(2) Palstar BT1500BAL to open wire.

As I see it from all the answers I've received, there are people with strong
opinions on both sides, that have just given me their conclusion: do x or do
y. But what I am still missing is WHY do x or y, and how they bounce off
one another.

FOR INSTANCE, WHICH COMBO, (1) OR (2) WILL GIVE THE LOWEST LOSS WHEN FEEDING
A BALANCED ANTENNA AT AN 8:1 SWR? HOW MUCH LOWER...LOSS 100 WATTS FOR ONE
AND 125 FOR THE OTHER? That is what I don't understand yet.

One gentleman did address my question of whether I could feed an Inverted L
(like on 160) with a balanced tuner if I used a balun to change the
unbalanced feed from the antenna to a balanced feed connected the output of
the balanced tuner, saying don't, but why not? Does this mean that a
balanced tuner can NEVER be used for UNbalanced loads through use of a
balun?

Another gentleman pointed out that most people just go unbalanced and don't
worry about the heat/loss in the balun...or change the length of the feed
line slightly (per Cecil's method) until you get a "happy" length the balun
can handle, and then buy the most rugged balun you can get to handle the
mismatches.

CONCLUSIONS SO FAR: As I see it, the 238B has versatility in that it can do
both balanced and unbalanced (with a good external balun instead of its
internal voltage balun), but the external balun will heat up and could even
fail at 1200 watts to a feed line feeding some mismatched frequencies. But I
could lengthen/shorten the balanced feed line to adjust it I guess, looking
for its happy spot! On the other hand, the PALSTAR will work great with
unbalanced lines (no lossy balun), even at high SWR, but it doesn't do
unbalanced lines (although one person mentioned the capacitor might be too
small for some situations--but I compared it and it seems to be larger and
higher rated (4.5 KV) than the Ten Tec). From your comments I gather that
almost any tuner or tuner-balun combo will do great at LOW SWR...but I don't
need a tuner for those situations. It's when the SWR gets up higher, like
8:1 or 16:1 that I am concerned about with 1200 watts. In ARRL tests, the
Palstar handled that OK, but no such tests for a 238B handling balanced
lines (only unbalanced lines a few years back in QST). And what about the
DXE, which W8JI tests highly rated, but (if I read the tests right) the
tests were done at approx. 1.5 to 1 SWR...no where near the 8 to 1 that I am
envisioning. Some of you have said the balun will heat up or even burn up
(although I understand the DXE is supposed to be rugged enough to only heat
up), but doesn't that rob me of all my power--heat is not a good thing!

And, if both will work, to some degree (barring the burnout of the balun),
is the 238B the way to go because I can ALSO do unbalanced lines for other
antennas?

I guess if I never wanted to have any unbalanced antennas in the future, I'd
go the balanced tuner and be done with it. But if the loss through the 238B
and DXE Tuner Balun would not be substantially greater than the Balanced
Tuner, but will permit me to match unbalanced lines too for future antennas,
then that sure seems the way to go (and adjust the feed line length to best
match).

What do you all think?

And thanks for you many replies that have brought me this far so far!

73,
Greg N6GK
Greg, N6GK

"Bob Miller" wrote in message
...
On Sun, 24 Jul 2005 11:32:37 -0700, "greg knapp 5"
wrote:

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner,
but reversed in direction (converting unbalanced to balanced), or need I
get
a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner,
will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced
(with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter
dipole instead?
Thanks & 73,
Greg, N6GK


Have not seen any published tests comparing balanced vs. unbalanced
tuners, so any comparisons will probably be theoretical in nature.
Also, instread of the dx engineering balun, you might look at a
w2du-style balun -- see his article at
http://www.w2du.com/Reflection2.html

bob
k5qwg

To answer your post:

Yes, I have looked carefully at the theoretical radiation pattern, and it is
acceptable for now due to a number of constraints I am working against that
do not permit something different.

My goal is to have a strong signal from my QTH out to about 700 miles on
80/75 (for a net for which I am net control), and a decent signal on the
rest of the HF bands. I am not so concerned about the peaks and valleys in
the radiation patter on the higher HF bands as after 45 years of hamming, my
#1 priority is no longer chasing DX pileups or contesting big time...I'd
rather spend my time meeting new hams and getting to know them (they are
really very interesting people!)...not just "599 CA" or "599 #683 about 600
times in two days. The gain peaks will give me plenty of people to talk
with.

I do not forsee having the ability to put up my beam and regular tower up
again for various reasons (mainly too much hassel, time, and expense with my
poor health), so basically all I have available is one 70 foot high mast
(last 30 feet of which are Radio Shack 10 foot sections) in the back sheep
pasture, that will have a low angle on the higher bands due to its height
that might help make up for no multi-element gain. I do have two multi-band
verticals, but the local noise is pretty bad...so hoping going horizontal
and perhaps an ANC-1 will provide better receive.

73,

Greg, N6GK


"Wes Stewart" wrote in message
...
On Sun, 24 Jul 2005 11:32:37 -0700, "greg knapp 5"
wrote:

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.

Is the radiation pattern on all of these bands acceptable/useful?

(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?

Study this before deciding: http://eznec.com/misc/ibalun.txt

Considering the capacitor in the Palstar isn't a balanced design, the
capacitive coupling from it to ground is asymetrical, so I would not
call it a balanced tuner. Also, I don't see anything that looks like
a 1500 W balun in there.

Ten Tec says, "Because there are only two variable components, there
is only one setting of each which will provide a perfect match to a
given load impedance. This unique setting automatically provides the
lowest Q network possible. Low Q means low circulating currents, hence
low loss, and it also provides the widest frequency bandwidth of
operation before retuning is necessary (very useful if you're moving
up and down the SSB portion of the band, for example)..."

They are correct when they say that there is only one setting for a
match, but the L-network Q is set by the load and source Z and is
likewise fixed and totally out of the control of the operator. This
may or may not give the largest operating BW and/or lowest loss.

For example, take a load Z of 5 -j10 at 7 MHz. With capacitor Q =1000
and inductor Q = 250 (good luck with a roller inductor), an L-network
of C = 1364 pF and L =0.568 uH will give SWR = 1.02. The network loss
will be 0.1 dB.

Using the same load Z and component Q, a high-pass-Tee network of Cin
= 1438 pF, L = 0.36 uH and Cout = 3912 pF will give SWR = 1.01 The
network loss will be 0.07 dB.

More parts, lower loss. So much for conventional wisdom. Now this is
a pretty wild load Z, but with certain antenna feedpoint Z and
transmission line lengths and Zo, it's possible. Admittedly, the
differences in insertion loss are negligble but they are different in
the -wrong- direction, thus proving the point.

Of course, try and find a tuner with capacitors of this high a value.

Also, there are some impedances that cannot be matched with either
configuration of a low-pass (series inductor) L-network. The same can
be said for any other topology, but you should be aware of this.

(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner,
but reversed in direction (converting unbalanced to balanced), or need I
get
a different tuner?

I wouldn't do this.

(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner,
will the balun waste a ton of RF in heat and loss?

Maybe. In my opinion balun loss is no different from line
attenuation. Line attenuation is magnified by SWR and I see no reason
why balun loss wouldn't be too, particularly since most baluns are
constructed from a transmission line.

(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced
(with balun) tuner.

(5) I have plenty of room, would it make any difference if I put a 160
meter
dipole instead?

If you have plenty of room, why limit yourself to one compromise
antenna?

Interesting article. I also read W8JI's article on baluns that discusses
this type of balun too. Very interesting. Current balun definitely seems the
ONLY way to go!

"Bob Miller" wrote in message
...
On Sun, 24 Jul 2005 11:32:37 -0700, "greg knapp 5"
wrote:

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with
a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar BT1500BAL
balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner,
but reversed in direction (converting unbalanced to balanced), or need I
get
a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner,
will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced
(with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter
dipole instead?
Thanks & 73,
Greg, N6GK


Have not seen any published tests comparing balanced vs. unbalanced
tuners, so any comparisons will probably be theoretical in nature.
Also, instread of the dx engineering balun, you might look at a
w2du-style balun -- see his article at
http://www.w2du.com/Reflection2.html

bob
k5qwg

I think you summarized it well. thanks!

"Dave" wrote in message
...

"Dave Platt" wrote in message
...
In article ,
Dave wrote:

how does the balanced tuner get from the unbalanced output of the
amplifier
and the balanced feedline? is there not a balun in there somewhere
anyway?

I've seen three approaches used:

- Asymmetrical (unbalanced) tuner of the T or L or pi configuration,
with a balun at the output. This seems to be the most common
configuration, but is often said to suffer from a degraded balance
or unacceptable losses in the balun when feeding high-Z loads.
It's not easy for a balun to provide adequate choking reactance
when feeding such loads.

- Tuners which use a symmetrical T or L configuration, with the input
to the matching network being fed from the rig/amplifier's 50-ohm
output via a balun. An internal W2DU-type "ferrite beads on coax"
balun seems to be popular in such designs.

- Link-coupled tuners, such as the Johnson Matchbox and the newer
Z-match designs. The input side of the circuit operates unbalanced
and is usually asymmetrical, while the output side (the link) is
balanced with respect to ground. The input and output sides are
coupled inductively. There's sometimes a small amount of imbalance
created by capacitive coupling across the link, but this seems to
be small enough to have little practical effect on the quality of
the balance. In this case, the balanced-to-unbalanced function is
performed by the inductive link, and there's no separate "balun"
component.

so, no matter how you spell it, unbalanced in, balanced out, somehow the
tuner either has a component called specifically a balun, or combines it
into other parts that also transform impedance... essentially making the
whole tuner one big balun. no matter how its done somewhere between the
amplifier unbalanced output and the balanced wire there is something doing
the balun function.

Large Toroid mounted on the inside back wall of the tuner.





Dave wrote:
how does the balanced tuner get from the unbalanced output of the amplifier
and the balanced feedline? is there not a balun in there somewhere anyway?

"greg knapp 5" wrote in message
...

I have decided to erect an 80 meter dipole at 70 feet fed with 450 or 600
ohm open wire, for use on ALL HF bands between 80 and 10 meters. Power
output will be 1000W CW and 1200W PEP.
(1) Which is the better setup and why: a Ten Tec 238B unbalanced tuner
with a DX Engineering 1:1 balun on antenna side of tuner OR a Palstar
BT1500BAL balanced tuner?
(2) Also, if I later decide to erect an inverted L for 160/80, can I use a
balanced tuner with a DX Engineering 1:1 balun put on antenna side of
tuner, but reversed in direction (converting unbalanced to balanced), or
need I get a different tuner?
(3) In a perfect world, I'd buy both tuners (one for balanced and one for
unbalanced), but I can't afford it. Also, if I go with the unbalanced
tuner, will the balun waste a ton of RF in heat and loss?
(4) I made a similar post on the Ten Tec List, and received lots of advice
on point designs, but not the COMPARISON data I was looking for that will
help me make the final decision to go with a balanced tuner vs an
unbalanced (with balun) tuner.
(5) I have plenty of room, would it make any difference if I put a 160
meter dipole instead?
Thanks & 73,
Greg, N6GK

I guess if I never wanted to have any unbalanced antennas in the future, I'd
go the balanced tuner and be done with it. But if the loss through the 238B
and DXE Tuner Balun would not be substantially greater than the Balanced
Tuner, but will permit me to match unbalanced lines too for future antennas,
then that sure seems the way to go (and adjust the feed line length to best
match).

What do you all think?

And thanks for you many replies that have brought me this far so far!

My suggestions:

Buy a used Johnson Matchbox for much less than the Palstar. Even the "low
power" Johnson will take a KW. Or if you have the $, get the Palstar.
Use it with a center-fed/ladder line dipole.

Re the inverted L: you are making it much too hard! Just put up a 160/80
inverted-L and feed it directly with coax. There is no need for a tuner
for this antenna (unless maybe you want to cover both CW and SSB on 80).
A separate 80m element can just be paralleled to the 160 wire, like a
"fan dipole". Put down lots of radials. To match the lower impedance on
160, just use a hairpin coil at the feedpoint.

Tor
N4OGW

On Sun, 24 Jul 2005 17:54:58 -0700, "greg knapp 5"
wrote:


I guess that is what MY REAL QUESTION boils down to...although I like the
"single resonant" L-type Ten Tec 238 unbalanced tuner (and it would work
great with my future inverted L), it needs a balun to match it to the open
wire feed. Will the balun, at HIGH SWRs, just burn up my watts in heat and
smoke?

My MFJ 989C matches an 80 meter dipole with ladderline on all bands
between 80 and 10. There is no smoke, no heat. With this antenna, I
use the standard balun built into the tuner. Other times, I've used
external chokes, either coiled coax or w2du type baluns. I'd recommend
a standard unbalanced T-circuit type tuner, for as much money as you
can afford. It'll do fine for a whole range of feeds, balanced or
otherwise.

bob
k5qwg

Just a note:

With a link-coupled tuner you can use either a balanced line (ladder line,
tv twin-lead) fed antenna or a coax fed antenna. It handles either equally
well.

Used Johnson Matchboxes are still fairly common on ebay in the $100 price
range. I use mine for all bands 80-10. If you want to roll your own link
coupled tuner see:
http://www.amfone.net/ECSound/K1JJ13.htm