On Mon, 07 Nov 2005 22:39:33 GMT, Ed
wrote:

Guys, please help me here. You are talking about UNUNs and BALUNs.
A balanced tuner OUTPUT to ladderline is BALANCED TO BALANCED , isn't
it? Why the need for anything, there?


Ed K7AAT

Ed,

His original posting said:
"Got a Radio Works choke balun I'd like to use for feeding ladderline
out of an *unbalanced* tuner."


Danny, K6MHE

email: k6mheatarrldotnet
http://www.k6mhe.com/

On Mon, 7 Nov 2005 12:07:30 -0600, "RB"
wrote:

Got a Radio Works choke balun I'd like to use for feeding ladderline out of
an unbalanced tuner.

The balun has coax fittings on each end.

I think from the sound of your description you have one of their
"isolaters" that has a coax socket on both ends.

These things are very neat when used to "choke" currents on the outer
of coax.


Ladderline doesn't adapt well to coax interfaces.

What's the best way to put ladderline to my balun coax fitting?

I can kluge a PL-259 plug onto the ladderline.

I guess I could also stick one side of the ladderline in the center hole of
the chassis coac fitting, and clamp the other side to the threaded part of
the chassis fitting.


That doesn't sound reliable, the "stick one side of the ladderline in
the center hole" bit, that is. How would you maintain reliable centre
contact. (BTW, you probably already know that 4mm banana plugs fit
into SO-239 neatly.)

What is your problem, is it the "inelegance" of soldering the openwire
ends to the coax plug, or are you concerned about impedance
discontinuity at presumably HF / 6m?

I am sure that you could look around and find adapters, I can think of
a few ways myself, but...

If it is not in the weather, I would just solder the ends of the open
wire to a PL-257 and screw in on. You could sleeve the end going to
the centre conductor to improve its flashover voltage if that is
likely to be an issue. (BTW, taking the earth side wire down inside
the PL259 and bringing it out the braid hole will give you quite a
neat finish.)

Owen
--

Ed wrote:
Cecil Moore wrote:
It depends on whether the very high SWR is on the ladder-line
side or on the coax side. :-)

Well, he said "OUT of an unbalanced tuner" so I assume that's the
ladderline side.

Yes, and with a reasonable limit, the SWR on the ladder-line
doesn't matter. IMO, 25:1 is no problem for ladder-line.
--
73, Cecil http://www.qsl.net/w5dxp

On Mon, 07 Nov 2005 23:26:47 GMT, Cecil Moore wrote:


Yes, and with a reasonable limit, the SWR on the ladder-line
doesn't matter. IMO, 25:1 is no problem for ladder-line.

There must be a host of unstated assumptions behind that statement to
make it valid in a limited scenario.

Using TLDETAILS to work up a load of 16+j0 on 100m of Wireman551
ladder-line at 30MHz, the predicted VSWR varies between 25 at the load
end and a very modest 6.5 at the generator end, yet the predicted loss
is around 6dB. Some might not find that an acceptable loss.

Owen
--

Owen Duffy wrote:
Using TLDETAILS to work up a load of 16+j0 on 100m of Wireman551
ladder-line at 30MHz, the predicted VSWR varies between 25 at the load
end and a very modest 6.5 at the generator end, yet the predicted loss
is around 6dB. Some might not find that an acceptable loss.

If 100m (325 feet) of ladder-line results in 6dB loss, then a more
realistic 75 feet of ladder-line will result in about 1.4 dB of loss.
That's only 1/4 of an S-unit on the highest frequency HF band and less
on the other bands. That's perfectly acceptable to me and virtually
indistinguishable on an S-meter.

If you have to resort to 325 feet of ladder-line on 30 MHz to try
to prove me wrong, I feel really sorry for you. Why didn't you choose
a million feet to prove me even more wrong? It appears that you are
lurking there in the down under outback just waiting for me to forget
to cross an 'i' or dot a 't'.
--
73, Cecil http://www.qsl.net/w5dxp

Well, he said "OUT of an unbalanced tuner" so I assume that's the
ladderline side.

Yes, and with a reasonable limit, the SWR on the ladder-line
doesn't matter. IMO, 25:1 is no problem for ladder-line.


Correct, a high SWR is not an issue for ladderline, but the guy was
wanting to stick an apparently 50 ohm coax balun right there in between
his balanced tuner output and that ladder line. I would think a high
SWR, with some TX power, in that device might not do it much good.


Ed

Guys, please help me here. You are talking about UNUNs and BALUNs.

A balanced tuner OUTPUT to ladderline is BALANCED TO BALANCED ,
isn't it? Why the need for anything, there?


His original posting said:
"Got a Radio Works choke balun I'd like to use for feeding ladderline
out of an *unbalanced* tuner."


My sincere appologies to this thread group. I read that original post
twice and still missed that the tuner was unbalanced output. Makes a
lot more sense, now.


Ed K7AAT

On Tue, 08 Nov 2005 02:09:13 GMT, Cecil Moore wrote:

Owen Duffy wrote:
Using TLDETAILS to work up a load of 16+j0 on 100m of Wireman551
ladder-line at 30MHz, the predicted VSWR varies between 25 at the load
end and a very modest 6.5 at the generator end, yet the predicted loss
is around 6dB. Some might not find that an acceptable loss.

If 100m (325 feet) of ladder-line results in 6dB loss, then a more
realistic 75 feet of ladder-line will result in about 1.4 dB of loss.

Close, I make it 2.2dB. (The loss per meter is not a constant figure
in this situation.) Agreed, even that is not a large amount, and
indeed might be quite acceptable in many / most cases.

That's only 1/4 of an S-unit on the highest frequency HF band and less
on the other bands. That's perfectly acceptable to me and virtually
indistinguishable on an S-meter.

If you have to resort to 325 feet of ladder-line on 30 MHz to try
to prove me wrong, I feel really sorry for you. Why didn't you choose
a million feet to prove me even more wrong? It appears that you are
lurking there in the down under outback just waiting for me to forget
to cross an 'i' or dot a 't'.

Cecil, people often employ long runs of open wire feed on HF (ie up to
30MHz), and it just shows that on longer runs, high VSWR can be an
issue for ladder line.

I often hear Rules of Thumb (ROT) like VSWR 3 is OK for coax and
25 if fine for open wire, or the converse... but something is lost in
the brief expression of those ROTs, and it seems more and more the
knowledge base of our hobby is the ROTs, rather than the underlying
principles. There is an appeal to the new experts in our hobby to
pickup the ROTs and parrot them... perhaps we need to take the time to
qualify what we say where learners are listening.

Owen
--

On Tue, 08 Nov 2005 03:07:10 GMT, Owen Duffy wrote:

I often hear Rules of Thumb (ROT) like VSWR 3 is OK for coax and
25 if fine for open wire, or the converse... but something is lost in
the brief expression of those ROTs, and it seems more and more the
knowledge base of our hobby is the ROTs, rather than the underlying
principles. There is an appeal to the new experts in our hobby to
pickup the ROTs and parrot them... perhaps we need to take the time to
qualify what we say where learners are listening.

Owen

Owen,

The problem is that knowing the SWR is not worth much without knowing
the frequency and the spec's of the transmission line.

For example an SWR ratio of 10:1 using a hundred feet of RG-217 on
the 80-meter band is only about 1 dB loss. On 10-meters its a
different story.

I still subscribe to the belief that judging antenna performance based
solely upon SWR is like judging how well a automobile will perform
based solely on what the air pressure is in the tires.

Danny, K6MHE

email: k6mheatarrldotnet
http://www.k6mhe.com/

How many hams find a feedline length of 100 Meters acceptable? Lets look at
a more realistic length of 100 feet and the loss is less than 2 dB at 30
Mhz. The loss is much less on the lower bands. With all due respect, your
example sucks!

"Owen Duffy" wrote in message
...
On Mon, 07 Nov 2005 23:26:47 GMT, Cecil Moore wrote:


Yes, and with a reasonable limit, the SWR on the ladder-line
doesn't matter. IMO, 25:1 is no problem for ladder-line.

There must be a host of unstated assumptions behind that statement to
make it valid in a limited scenario.

Using TLDETAILS to work up a load of 16+j0 on 100m of Wireman551
ladder-line at 30MHz, the predicted VSWR varies between 25 at the load
end and a very modest 6.5 at the generator end, yet the predicted loss
is around 6dB. Some might not find that an acceptable loss.

Owen
--