On Mar 4, 5:48 pm, Mike Coslo wrote:
Solid state transmitters are notoriously finicky about matching to the
antenna. Tube equipment is not, so I am told, and early experience seems
to bear that out.

I don't know if "finicky" is a good term, Mike. "Different" might be
the best word to use. Transmitters with vacuum tube finals can match
a wider range as a rule, but there is a limit to what they can
handle. Some of the older Johnson and Globe/WRL rigs matched a wider
range than some of the other brands.

Certainly I can see one of my newer rigs start to fold back at 2:1.

Most Japanese gear is designed to do just what you're experiencing.
That's a form of protection for the final transistors. Ten-Tec does
it differently. Ten-Tec rigs do not start to reduce power. They
depend upon the supply to fault and trip if too much current is
drawn. That's why it is important to use a Ten-Tec supply with them
or to use a fast breaker rated to trip near the maximum current draw
expected of the transmitter.

What are the practical limitations of the Tube finals apparent
flexibility?

That depends entirely upon the design specifications set by the
manufacturer.
If the manufacturer's manual says "45-90 ohms", that's the practical
limitation.
Some of those old Globe transmitters used to have ranges of up to 1000
or 2000 ohms as I recall. At the other end of the spectrum,
Hallicrafters produced some transmitters without even a loading
control. These were designed to be used with an antenna presenting
something very close to 50 or 75 ohms.

Is it safe to compare the load, plate, and drive controls to some of the
functions of a tuner? (possible real dumb question)

Not the "drive" control, but certainly the other controls of a tuner
could be considered comparable to the "tune" and "load" controls.

If the only antennas we have are trapped verticals, tribanders or
dipoles/inverted vees cut for the band to be used, we might get away
with not having to use a tuner at all. Still there are likely to be
frequencies significantly removed from the antenna's resonant
frequency where one might need a tuner to enable the transmitter to
make full power. We aren't likely to need a wide range tuner for
those times. A simple T-match will likely enable us to find a
combination of settings which will present a low VSWR to the
transmitter. The main alternative is to have a variety of antennas
which present a VSWR of under 2:1 to a transmitter.

Dave K8MN

wrote:

If the only antennas we have are trapped verticals, tribanders or
dipoles/inverted vees cut for the band to be used, we might get away
with not having to use a tuner at all. Still there are likely to be
frequencies significantly removed from the antenna's resonant
frequency where one might need a tuner to enable the transmitter to
make full power. We aren't likely to need a wide range tuner for
those times. A simple T-match will likely enable us to find a
combination of settings which will present a low VSWR to the
transmitter. The main alternative is to have a variety of antennas
which present a VSWR of under 2:1 to a transmitter.

That brings up a related issue. Lots of Hams today are restricted to
one antenna, yet they would like all band operation. I think it would be a
great idea for a manufacturer to have a transciever that included a tuner
right in the rig itself.

- 73 de Mike KB3EIA -

"Mike Coslo" wrote in message
6
wrote:

If the only antennas we have are trapped verticals,
tribanders or dipoles/inverted vees cut for the band to
be used, we might get away with not having to use a
tuner at all. Still there are likely to be frequencies
significantly removed from the antenna's resonant
frequency where one might need a tuner to enable the
transmitter to make full power. We aren't likely to
need a wide range tuner for those times. A simple
T-match will likely enable us to find a combination of
settings which will present a low VSWR to the
transmitter. The main alternative is to have a variety
of antennas which present a VSWR of under 2:1 to a
transmitter.

That brings up a related issue. Lots of Hams today are
restricted to one antenna, yet they would like all band
operation. I think it would be a great idea for a
manufacturer to have a transciever that included a tuner
right in the rig itself.

- 73 de Mike KB3EIA -

They do exist, although being primarily interested in VHF/UHF operation
(we only recently had the morse requirement for HF dropped over here in
the UK, but that's another topic..!!) I've had little experience of them.

I do remember vividly using a Drake commercial HF transceiver (I think it
came out of a ship's radio room) back in the late 80's at a special event
station that had this feature, you could operate on any band without any
form of tuning at all, although of course how much power would get out on
a really bad antenna is debatable ;-)

Of course if you've enough money, there are those antennas that tune
themselves. A friend has a 3-element beam that is computer controlled; as
you tune across the bands, the elements automatically adjust themselves to
the correct length..! I don't recall the make/model, but it is of American
origin, does anyone know of it..?

73 Ivor G6URP

"Ivor Jones" wrote in message
...
"Mike Coslo" wrote in message
6
wrote:


[snip]


That brings up a related issue. Lots of Hams today are
restricted to one antenna, yet they would like all band
operation. I think it would be a great idea for a
manufacturer to have a transciever that included a tuner
right in the rig itself.

- 73 de Mike KB3EIA -

They do exist, although being primarily interested in VHF/UHF operation
(we only recently had the morse requirement for HF dropped over here in
the UK, but that's another topic..!!) I've had little experience of them.


My main HF rig and my husband's main HF rig both have built in tuners. Both
work pretty well. However they do not have the range of outboard tuners.

I do remember vividly using a Drake commercial HF transceiver (I think it
came out of a ship's radio room) back in the late 80's at a special event
station that had this feature, you could operate on any band without any
form of tuning at all, although of course how much power would get out on
a really bad antenna is debatable ;-)


A lot of commericial and military equipment have built in tuners with quite
significant tuning ranges. Of course this comes at a price so amateur gear
doesn't have as much range in their tuning capacity on the built in tuners.

Of course if you've enough money, there are those antennas that tune
themselves. A friend has a 3-element beam that is computer controlled; as
you tune across the bands, the elements automatically adjust themselves to
the correct length..! I don't recall the make/model, but it is of American
origin, does anyone know of it..?

73 Ivor G6URP

I think it is called the SteppIR. Too rich for my pocket book.

Dee, N8UZE

"Dee Flint" wrote in
:


My main HF rig and my husband's main HF rig both have built in tuners.
Both work pretty well. However they do not have the range of
outboard tuners.

I should have noted large range and balanced/unbalanced output. My
IC-761 has an autotuner on it that works pretty well with my vertical
antenna. The dipole is run with balanced line, and needs a different
tuner.


A lot of commericial and military equipment have built in tuners with
quite significant tuning ranges. Of course this comes at a price so
amateur gear doesn't have as much range in their tuning capacity on
the built in tuners.

Size can be an issue too. The IC 761's tuner is a pretty tiny
thing. I had to take an IC 765's autotuner 9 (very similar) apart once to
repair it, and it was around the size of one of the mfj tiny tuners.

A little bigger components, plus a 4:1 balun, and they would have
it.

- 73 de Mike KB3EIA -

On Mar 4, 10:23�pm, Mike Coslo wrote:
* * * * I should have noted large range and balanced/unbalanced output. My
IC-761 has an autotuner on it that works pretty well with my vertical
antenna. The dipole is run with balanced line, and needs a different
tuner.

---

* * * * A little bigger components, plus a 4:1 balun, and they would have
it.

Well, sort of.

The Ancient Ones used antenna matching
devices to feed balanced lines. The Johnson
Matchboxes are one example of a commercial
version. Most Handbooks have examples of
link-coupled balanced wide-range tuners.

The problem was that such link-coupled tuners are large
and not easy to bandswitch.

About 1970, a new idea in tuners appeared: Use an
unbalanced matching network such as a T or L
network with a roller inductor or tapped inductor, with a
balun if balanced output was wanted. 4:1 iron-core toroid
baluns were compact and broadband, the T or L tuner
could be made wide-range without complex bandswitching,
and the whole works seemed an improvement on the old
link-coupled balanced tuner.

The problem was that baluns aren't magic devices. The
system works well if the shack-end of the transmission line
is around 200 ohms impedance and not too reactive. But in
many cases the shack-end impedance with balanced line
is very high or very low, and/or very reactive. Under such
conditions the balun may not do a very good job because it is
being asked to work far outside its design parameters.

Also, if the shack-end impedance is low (say, 12 ohms), the
use of a 4:1 balun will make it so low (3 ohms) that it may be outside
the efficient matching range of the T or L network.

These conditions may be partially remedied by use of a balun
that can be switched to either 4:1 or 1:1 ratio, and by choosing
antenna and feedline combinations that don't result in extreme
values of shack-end impedance/reactance. But that reduces
the flexibility of the system.

The "unbalanced tuner followed by a balun" idea is clearly
one where "newer" wasn't necessarily "better" in all cases.
Yet it became very popular because it usually worked.
But in many cases the balanced line was actually
doing a lot of radiating and there was considerable loss in the
system.

Back in 1990, AG6K came up with an answer to the
shortcomings of that method. He put a 1:1 balun between the
rig and a simple balanced tuner, so the balun only has to
deal with a pure 50 ohm load once the tuner is adjusted.
Although AG6K favors baluns made from coax wound on
PVC pipe, other forms of balun such as ferrite-bead and
wound-toroid can be used if preferred.

You can read AG6K's article he

http://www.somis.org/bbat.html

and judge for yourself.

AG6K's approach used two ganged roller inductors and
a single variable capacitor, compared to most commercial
manual tuners that use two variable caps and a single variable
inductor. Because there are only two controls, remoting the
tuner is made easier.

73 de Jim, N2EY

wrote:


These conditions may be partially remedied by use of a balun
that can be switched to either 4:1 or 1:1 ratio, and by choosing
antenna and feedline combinations that don't result in extreme
values of shack-end impedance/reactance. But that reduces
the flexibility of the system.

True enough.

snip



You can read AG6K's article he

http://www.somis.org/bbat.html

and judge for yourself.

I have gathered the parts to make just that!. I'd have it up now, but I
switched to a coax fed antenna for a while, and built a more traditional
tuner. In the interim I went back to balanced line.


AG6K's approach used two ganged roller inductors and
a single variable capacitor, compared to most commercial
manual tuners that use two variable caps and a single variable
inductor. Because there are only two controls, remoting the
tuner is made easier.

Some day I'll report on how mine is doing. In the present situation I
don't need remote tuning, but will probably motorize the unit anyway.

- 73 de Mike KB3EIA -

wrote:
[snip]
The "unbalanced tuner followed by a balun" idea is clearly
one where "newer" wasn't necessarily "better" in all cases.
Yet it became very popular because it usually worked.
But in many cases the balanced line was actually
doing a lot of radiating and there was considerable loss in the
system.

Back in 1990, AG6K came up with an answer to the
shortcomings of that method. He put a 1:1 balun between the
rig and a simple balanced tuner, so the balun only has to
deal with a pure 50 ohm load once the tuner is adjusted.
Although AG6K favors baluns made from coax wound on
PVC pipe, other forms of balun such as ferrite-bead and
wound-toroid can be used if preferred.
[snip]

I'm not sure a "balanced" tuner is required. I have an off-center-fed
dipole I use with 600 ohm ladder line, and I'd like to try it with an
Ultimate Transmatch. If I put AG6K's coax balun on the input and isolate
the chasis from ground, wouldn't that achieve the same result?

Bill


--
73,

Bill W1AC

(Remove "73" and change top level domain for direct replies)

Mike Coslo wrote:

A little bigger components, plus a 4:1 balun, and they would have
it.

I wish that the manufacturers would include the provision for balanced
feedline. The random-length dipole, fed with balanced line, is an ideal
antenna in many cases. It's especially appropriate for disaster
situations (and simulated disasters, like Field Day). Find the two
highest supports that are available, as far apart as possible, measure
the distance, cut the wire and install the middle insulator and
feedline, hoist each end, and you're done. Now you've got a reasonably
efficient radiator (especially if there's enough distance between those
two supports) that you can use on any band, and the length of the
feedline isn't particularly critical. But it takes a tuner and balun to
make it work, and if this was included in the rig and was automatic, it
would be ideal.

73, Steve KB9X

On Mar 4, 7:09?pm, Mike Coslo wrote:

. Lots of Hams today are restricted to
one antenna, yet they would like all band operation. I think it would be a
great idea for a manufacturer to have a transciever that included a tuner
right in the rig itself.

Many rigs offer that as an option. For example, the Elecraft K2 can be
equipped with the optional KAT2 internal automatic antenna tuner. In
my experience, the KAT2 can match at least a 10:1 SWR, if not more. It
doesn't have
manual adjustments, however - it's a form of autotuner.

The 100 watt version of the K2 can be equipped with the
matching external tuner.

One interesting feature of these autotuners is that they
automatically reduce power to a few watts while the tuning routine is
operating.

I don't know of any solidstate HF ham rig with a *manual*
tuner built-in.

73 de Jim, N2EY