TT-247 and 102 whip for mobile antenna ?
 

I have a TenTec 247 manual antenna tuner. I am thinking about
installing a roof-mount over the space between the driver and
passenger in the front of my mini-van and hanging my TT tuner below
it. I understand the combination with automatic tuners works well,
but I have been warned against using the TT to tune short antennas on
low frequencies. Of course, this was in reference to dipoles and base
antennas. The problem is reportedly that the loading coil will heat
up and be damaged and have to be re-wound.

I have about a 2 foot extension that I may also use to extend the
antenna a little.

I don't have the money to spend on auto-tuners and I have everything
but the whip and mount for the antenna configuration I just described.

comments?


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

If there is a heating problem with a short dipole, there will be a
heating problem with a 102" whip.

Some automatic tuners may do OK with the short whip. I think SGC does
this, but if it works and is reasonably low-loss it is because the
tuner is designed to do well with a short whip.

One way to make the tuner match a short whip better on low frequencies
is to include a loading coil, in this case, at the base, to bring the
antenna into resonance. The impedance of the antenna will then be a low
resistive impedance, rather than a low resistive part and lots of
capacitative reactance. The tuner will handle this better than the
very short whip without a coil.

It seems to me that a short-whip automatic tuner should have an
inductance in series with the antenna input, maybe a LCL tee network.
I don't know what sort of topology the T-T 247 has but I don't think
anyone is building an LCL tee manual antenna tuner. It'd be easy to do
in an auto tuner though.

Anyone know the internals of the SGC short whip tuner (the one with the
whip mounted to it)?

Dan,
N3OX

TT-247 and 102 whip for mobile antenna ?
 

In doing a bit of google searching for

short unloaded whip tuner

I've found some sources that say that the auto tuners tend to have a
wider efficient matching range than the typical manual tuner.

So it may have nothing to do with network topology, it's just that if
you can manage to match a very short unloaded whip with your typical
manual tuner, you're going to be out at the edge of the matching range
where it is quite inefficient.

What's the group experience with this? If it's true that the automatic
tuners tend to be more efficient for a given range of impedances, what
are likely reasons?

Can the typical auto tuner switch from LCL tee to CLC tee? Pi to Tee?

Is it always going to be better to use a binary switched inductor and
capacitor system as opposed to a variable capacitor/tapped inductor
system?

Maybe it's just that the latter usually gets shoved into a tiny box and
the inductor Q is ruined?

Dan,
N3OX

TT-247 and 102 whip for mobile antenna ?
 

On 28 Apr 2006 08:52:31 -0700, "
wrote:

Hi Dan,

There are so many red lights going on, this was impossible to pass up.

I've found some sources that say that the auto tuners tend to have a
wider efficient matching range than the typical manual tuner.

Unless "they" can tie this to known antenna impedances, such claims
are worthless. And for another, what are the "typical" tuners that
are being compared to? Its easy enough to say what they are if it was
easy enough to measure them to support this claim.

So it may have nothing to do with network topology, it's just that if
you can manage to match a very short unloaded whip with your typical
manual tuner, you're going to be out at the edge of the matching range
where it is quite inefficient.

Matching and effeciency are only distantly related. Using padding
resistors could pull any antenna into a match - not much efficiency
there.

What's the group experience with this? If it's true that the automatic
tuners tend to be more efficient for a given range of impedances, what
are likely reasons?

There's a sucker born every minute?

Can the typical auto tuner switch from LCL tee to CLC tee? Pi to Tee?

That would have seem to have answered itself if your survey of
different auto-tuners was useful. Barring these results being
obvious, it would seem you simply discovered the font of Marketing
hype.

Is it always going to be better to use a binary switched inductor and
capacitor system as opposed to a variable capacitor/tapped inductor
system?

Depends on the granularity. Binary could mean one of two, or one of
1024.

Maybe it's just that the latter usually gets shoved into a tiny box and
the inductor Q is ruined?

For auto-tuners, that should be evident - and a marked counter to the
claim of greater efficiency.

73's
Richard Clark, KB7QHC

TT-247 and 102 whip for mobile antenna ?
 

On Fri, 28 Apr 2006 10:53:33 -0400, Buck wrote:

I have been warned against using the TT to tune short antennas on
low frequencies.

Hi Buck,

Such advice is worthless as it says nothing about frequency, nor
shortness.

Of course, this was in reference to dipoles and base antennas.

Of course, nothing! The tuner has no way of distinguishing any
antenna and the lead from it as anything but a load.

The problem is reportedly that the loading coil will heat
up and be damaged and have to be re-wound.

No doubt.

I have about a 2 foot extension that I may also use to extend the
antenna a little.

Try it with a "short" 160M antenna, and folks will be making coil
winding gestures next to their heads for you.

I don't have the money to spend on auto-tuners and I have everything
but the whip and mount for the antenna configuration I just described.

You must have some idea of what band you are going to use it on, what
is it?

73's
Richard Clark, KB7QHC

Automatic tuner efficiency survey... from TT-247 and 102 whip
 

Richard, first I'll say that I did NOT find a survey, I've seen
statements to this effect. (See http://www.eham.net/articles/4424) Of
course, I've found statements to the contrary.

I'd like to collect some data points if people have actually measured
the input and output power of their tuner into various loads, and I'll
keep looking for real data.

I'd also like to focus my question about matching range and efficiency
and retract all the other questions for now. I realize reading your
response that I asked a bunch of general questions that were at best
ill-defined an at worst trolly-sounding.

Pick a topology, let's say the shunt L tee (CLC) because it's so
common. Assume your tuner (the one who tunes), human or
microprocessor, is smart enough to select the most efficient values of
C1, L and C2 if there happens to be more than one solution for a
particular set of impedances.

Let's say I have a range of impedances within which I can get a 1:1 50
ohm SWR: How about the interior of the rectangle between 5 and 1000
ohms resistance, -500 to 500 ohms reactance.

Then take the subregion of that rectangle where efficiency of the tuner
is greater than some value, say, 79.4% (so you're losing no more than
1dB in the tuner)

Here's one question:

Is that subregion really complicated, with lots of small spots where
you can get an efficient match right next to spots where you're dumping
lots of power into the tuner, or is the variation more smooth?

I'll leave it at that for now. I've got more questions that would pend
knowing the answer to that one.

I may have to sit down with one of the CLC tuner simulators and make
myself a plot.

Dan
N3OX












Richard Clark wrote:
On 28 Apr 2006 08:52:31 -0700, "
wrote:

Hi Dan,

There are so many red lights going on, this was impossible to pass up.

I've found some sources that say that the auto tuners tend to have a
wider efficient matching range than the typical manual tuner.

Unless "they" can tie this to known antenna impedances, such claims
are worthless. And for another, what are the "typical" tuners that
are being compared to? Its easy enough to say what they are if it was
easy enough to measure them to support this claim.

So it may have nothing to do with network topology, it's just that if
you can manage to match a very short unloaded whip with your typical
manual tuner, you're going to be out at the edge of the matching range
where it is quite inefficient.

Matching and effeciency are only distantly related. Using padding
resistors could pull any antenna into a match - not much efficiency
there.

What's the group experience with this? If it's true that the automatic
tuners tend to be more efficient for a given range of impedances, what
are likely reasons?

There's a sucker born every minute?

Can the typical auto tuner switch from LCL tee to CLC tee? Pi to Tee?

That would have seem to have answered itself if your survey of
different auto-tuners was useful. Barring these results being
obvious, it would seem you simply discovered the font of Marketing
hype.

Is it always going to be better to use a binary switched inductor and
capacitor system as opposed to a variable capacitor/tapped inductor
system?

Depends on the granularity. Binary could mean one of two, or one of
1024.

Maybe it's just that the latter usually gets shoved into a tiny box and
the inductor Q is ruined?

For auto-tuners, that should be evident - and a marked counter to the
claim of greater efficiency.

73's
Richard Clark, KB7QHC

TT-247 and 102 whip for mobile antenna ?
 

Not counting the potential tuner problems you mention, my experience is
a 102” whip with no loading will work ok on 10-20m, but on 40m and below
it sucks.
Bob

Buck wrote:
I have a TenTec 247 manual antenna tuner. I am thinking about
installing a roof-mount over the space between the driver and
passenger in the front of my mini-van and hanging my TT tuner below
it. I understand the combination with automatic tuners works well,
but I have been warned against using the TT to tune short antennas on
low frequencies. Of course, this was in reference to dipoles and base
antennas. The problem is reportedly that the loading coil will heat
up and be damaged and have to be re-wound.

I have about a 2 foot extension that I may also use to extend the
antenna a little.

I don't have the money to spend on auto-tuners and I have everything
but the whip and mount for the antenna configuration I just described.

comments?

TT-247 and 102 whip for mobile antenna ?
 

On 28 Apr 2006 08:29:58 -0700, "
wrote:

If there is a heating problem with a short dipole, there will be a
heating problem with a 102" whip.

Some automatic tuners may do OK with the short whip. I think SGC does
this, but if it works and is reasonably low-loss it is because the
tuner is designed to do well with a short whip.

One way to make the tuner match a short whip better on low frequencies
is to include a loading coil, in this case, at the base, to bring the
antenna into resonance. The impedance of the antenna will then be a low
resistive impedance, rather than a low resistive part and lots of
capacitative reactance. The tuner will handle this better than the
very short whip without a coil.

It seems to me that a short-whip automatic tuner should have an
inductance in series with the antenna input, maybe a LCL tee network.
I don't know what sort of topology the T-T 247 has but I don't think
anyone is building an LCL tee manual antenna tuner. It'd be easy to do
in an auto tuner though.

Anyone know the internals of the SGC short whip tuner (the one with the
whip mounted to it)?

Dan,
N3OX

I believe my tuner is CLC, it has two caps and the inductor.


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Fri, 28 Apr 2006 10:52:54 -0700, Richard Clark
wrote:


You must have some idea of what band you are going to use it on, what
is it?

73's
Richard Clark, KB7QHC


Thanks, Richard for the comments. I would like to use it for 75-6
meters as I am not worried about 160 meters. I would like to use it
on 75 meters, as it is the band most likely to meet the coverage I am
interested in, but also to operate all bands as I would like not to
change antennas all the time. I have loaded the 20 meter and 40 meter
antennas with it to see how it works on other bands, but they really
suck!. I don't know if it is the way they are wound or what, but
tuning the 20 for six works well, but not with other bands. Going
lower doesn't help.

As for the mobile vs base antennas, there may be some difference. The
problem occurs when using a quarter wave or shorter dipole. However,
a quarter wave vertical is a match! This is part of my questioning.
Also, the fact that the tuner will be virtually at the antenna rather
than the coax, may make some difference, although, technically, I
think the coax would lower the reflected power to the tuner.

The theory i was hearing was that the loading coil takes all the
missing length of antenna and heats up. I can't imagine auto-tuners
having as large a coil as this manual tuner. (It uses a wire wrapped
around a toroid of some sort. ) I imagine an autotuner uses much
smaller inductors tied together thru relays.

I am trying to think of a type thurmometer that I could use that
wouldn't interact with the tuner to see if it heats up.

I will probably test the antenna this weekend if I can get the parts
and time....


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote:

Not counting the potential tuner problems you mention, my experience is
a 102” whip with no loading will work ok on 10-20m, but on 40m and below
it sucks.
Bob

with no tuning? you get acceptable match to your rig without a tuner,
would you explain more?

thanks
Buck
--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote:

Not counting the potential tuner problems you mention, my experience is
a 102” whip with no loading will work ok on 10-20m, but on 40m and below
it sucks.
Bob


I would expect it to suck on the lower bands. I am trying to figure
out some form of loading that will be cheap and simple to use. I have
a 40 meter whip and I guess I could add the 102 to the top for a
stinger, but that would make for a long and weak (physically) antenna.

75 mobile sucks under the best of conditions. That much I know. I
may have to settle for a 75/80 meter antenna option. I am trying to
think of a way to add a base coil that may allow me to tune lower
bands more easily without upsetting the higher bands. I don't want to
tune the coil itself every time I change bands, but I wouldn't mind
bypassing the coil on those times I would rather not tune 80/40. I am
very interested in operating 60 meters mobile on a regular basis as
well as 20 and up.

Buck


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Fri, 28 Apr 2006 22:57:40 -0400, Buck wrote:
I would like to use it for 75-6
meters as I am not worried about 160 meters. I would like to use it
on 75 meters, as it is the band most likely to meet the coverage I am
interested in,

Hi Buck,

All reports of short, mobile antennas on 80M generally cry crippled.
That is, unless, they are augmented by center loads under top hats a
dozen feet high or more. Even then, hardly remarkable unless you can
stand to be down 2 S-Units out the gate. For some, this knowledge is
a killer. For others who ignore it, they simply work those who can
hear them.

but also to operate all bands as I would like not to
change antennas all the time. I have loaded the 20 meter and 40 meter
antennas with it to see how it works on other bands, but they really
suck!.

Well, again, you are short on details. These two antennas (I presume
you have introduced two more to the discussion) may be air cooled
resistors for all their qualities you suggest. You might find an
object lesson here.

I don't know if it is the way they are wound or what, but
tuning the 20 for six works well, but not with other bands. Going
lower doesn't help.

Barring details....

As for the mobile vs base antennas, there may be some difference. The
problem occurs when using a quarter wave or shorter dipole.

Mobile quarterwave dipole?

However,
a quarter wave vertical is a match! This is part of my questioning.

Aside from this being natural, what could the question be?

Also, the fact that the tuner will be virtually at the antenna rather
than the coax, may make some difference, although, technically, I
think the coax would lower the reflected power to the tuner.

Many antennas are designed with a match external to them, but quite
close by. Why would this be detrimental? Even more, many antennas
are built with the match as part of them. They go by many names,
Gamma being one. Certainly nothing is lost in their use.

The theory i was hearing was that the loading coil takes all the
missing length of antenna and heats up.

Dare I say you can't trust everything you hear (read here)?

Myself, I taught RF communications in the Navy and had no trouble
whatever with the concept that a coil replaces the electrical length
missing in a short antenna. However, the Navy was never a slave to
fashion nor strict interpretation in this matter, and it was enough to
observe this quid-pro-quo as symbolic, and not literal.

I can't imagine auto-tuners
having as large a coil as this manual tuner. (It uses a wire wrapped
around a toroid of some sort. ) I imagine an autotuner uses much
smaller inductors tied together thru relays.

Indeed.

I am trying to think of a type thurmometer that I could use that
wouldn't interact with the tuner to see if it heats up.

Yuri might suggest aquarium thermometers (Liquid Crystal) - but you
would have to make sure the entire surface fit the entire strip (or
versa vice). If you have a very old digital camera, then they were
sensitive to IR. You could take a picture in the dark and resolve hot
spots.

I will probably test the antenna this weekend if I can get the parts
and time....

Further reports would be interesting.

73's
Richard Clark, KB7QHC

TT-247 and 102 whip for mobile antenna ?
 

On Fri, 28 Apr 2006 22:07:00 -0700, Richard Clark
wrote:

On Fri, 28 Apr 2006 22:57:40 -0400, Buck wrote:
I would like to use it for 75-6
meters as I am not worried about 160 meters. I would like to use it
on 75 meters, as it is the band most likely to meet the coverage I am
interested in,

Hi Buck,

All reports of short, mobile antennas on 80M generally cry crippled.
That is, unless, they are augmented by center loads under top hats a
dozen feet high or more. Even then, hardly remarkable unless you can
stand to be down 2 S-Units out the gate. For some, this knowledge is
a killer. For others who ignore it, they simply work those who can
hear them.

I realize this. I have used a Hustler on 75 before. I was definitely
a weak signal station. I can only imagine that a tuned whip would
generate similar results, or more likely, poorer results.

but also to operate all bands as I would like not to
change antennas all the time. I have loaded the 20 meter and 40 meter
antennas with it to see how it works on other bands, but they really
suck!.

Well, again, you are short on details. These two antennas (I presume
you have introduced two more to the discussion) may be air cooled
resistors for all their qualities you suggest. You might find an
object lesson here.

There are a total of four antennas I have mentioned in here for
comparison sake. The Hustler, just mentioned above, the 102 whip with
a possible 2 foot extension, and two Antenna Specialists (AS) (look
exactly like HamSticks). I haven't had the Hustler for over a decade.
I will introduce another antenna in this message later.

The AS antennas are thin fiberglass poles with long stingers on the
top. The fiberglass poles, of course, have copper wound around them
from bottom to top, above which is a whip (stinger) about the same
length as the pole. The hustler was a center loaded trap that was
several inches in diameter and about 10-12 inches tall (the trap part)
with a stinger on top. (You are probably familiar with the Hustler.)
I also have a Volvo brand CB whip. It is a thin fiberglass whip
similar to the bottom portions of the AS antennas, but it does not
have a stinger. Like the AS antennas, the fiberglass has copper wire
wound from bottom to top with the top tightly wound and the bottom
section loosely wound. There is no stinger on top of the CB antenna.

I previously did a little experimenting with the two AS antennas and
the Volvo CB antenna (I don't have the 102 whip yet.) I used the tuner
to compare receive signals on various active bands. the results
weren't very good. Basically, each antenna performed best on the
frequencies for which they were designed (no big surprise here) but
they performed terribly on any other band. In fact, they were not
even acceptable for use on other bands. The signal strength on 20
meters, for example went from s-9 on the 20 AS antenna to less than
s-2 on the other antennas. I know others who have used the 102 steel
whip/auto-tuner combination that I have talked to never complained
that they only received s-2 signals with the system. Therefore, my
theory is that the winding of the coil on the fiberglass poles is
adversely affecting the radiation on out-of-band operation. I am
hoping that the steel whip, with or without the extension, will
perform better on all bands than any of these antennas tested. I
realize it is a compromise but the loss of an s-unit or two in
exchange for all band coverage for my mobile without having to switch
antennas or get out of the car and change taps is an acceptable
trade-off.

Remember, too, that in the original post, money is a big issue. The
purchase of a screwdriver (the best known mobile antenna design for
all band coverage) is not an option at this time. My theory is that I
should be able to mimic the 102 whip/auto-tuner results using a manual
tuner. My question is whether or not the tuner itself can hold up to
the task without being damaged.





I don't know if it is the way they are wound or what, but
tuning the 20 for six works well, but not with other bands. Going
lower doesn't help.

Barring details....

I think I addressed that above, the fiberglass poles are wrapped
tightly at the top and then loosely to the bottom, a stinger extends
from the tops of the AS antennas, and the Volvo antenna doesn't have a
stinger.


As for the mobile vs base antennas, there may be some difference. The
problem occurs when using a quarter wave or shorter dipole.

Mobile quarterwave dipole?
base. The suggestion I was given was not to use the antenna tuner on
a 20 meter dipole to tune a 40 meter frequency. This would be a 1/4
wave dipole on 40 meters. I don't know what the impedance of such an
antenna would be, but I do know that a 1/4 wave vertical is a
reasonable match. We never discussed the use of the tuner in the
mobile.



However,
a quarter wave vertical is a match! This is part of my questioning.

Aside from this being natural, what could the question be?

Also, the fact that the tuner will be virtually at the antenna rather
than the coax, may make some difference, although, technically, I
think the coax would lower the reflected power to the tuner.

Many antennas are designed with a match external to them, but quite
close by. Why would this be detrimental? Even more, many antennas
are built with the match as part of them. They go by many names,
Gamma being one. Certainly nothing is lost in their use.

The theory i was hearing was that the loading coil takes all the
missing length of antenna and heats up.

I should have clarified that this statement. The internal inductor of
the tuner makes up the missing length of the antenna and heats up
which can cause damage to the antenna tuner's inductor. This is how
it was presented to me, or how I understood it. Again, the discussion
was using the tuner to tune short dipoles to transmit on lower
frequencies.


Dare I say you can't trust everything you hear (read here)?

Myself, I taught RF communications in the Navy and had no trouble
whatever with the concept that a coil replaces the electrical length
missing in a short antenna. However, the Navy was never a slave to
fashion nor strict interpretation in this matter, and it was enough to
observe this quid-pro-quo as symbolic, and not literal.

I can't imagine auto-tuners
having as large a coil as this manual tuner. (It uses a wire wrapped
around a toroid of some sort. ) I imagine an autotuner uses much
smaller inductors tied together thru relays.

Indeed.

I am trying to think of a type thurmometer that I could use that
wouldn't interact with the tuner to see if it heats up.

Yuri might suggest aquarium thermometers (Liquid Crystal) - but you
would have to make sure the entire surface fit the entire strip (or
versa vice). If you have a very old digital camera, then they were
sensitive to IR. You could take a picture in the dark and resolve hot
spots.

I will probably test the antenna this weekend if I can get the parts
and time....

Further reports would be interesting.



I have been scheduled to work this weekend. I hope to be off Sunday,
If I can, I will try testing the whip idea using the side mount on the
van and if it appears to be promising, I will drill the holes in the
roof to mount the whip there near the radio and tuner.


73's
Richard Clark, KB7QHC
73 for now

--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Fri, 28 Apr 2006 23:07:32 -0400, Buck wrote:

On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote:

Not counting the potential tuner problems you mention, my experience is
a 102” whip with no loading will work ok on 10-20m, but on 40m and below
it sucks.
Bob

with no tuning? you get acceptable match to your rig without a tuner,
would you explain more?

thanks
Buck


I just re-read your statement. Are you saying the whip without a
loading coil used thru a tuner? My first thoughts were you meant
without a tuner.

I expect that 40 and below will be a bit poor. I hope to find a
compromise of sorts where I can add a loading coil, but only change it
when I want to operate 40-80 meters, sort of a switch between the
higher and lower bands as opposed to setting it for each band. The
alternative may be to have two antennas, one for the lower bands, set
as needed per band, and one for the upper bands that only needs tuning
with the tuner. If I am lucky, I may be able to have one with a
loading coil that tunes all the lower bands relatively efficiently and
the whip for the upper bands. I can deal with two antennas, I have a
switch but my problem right now is I have separate 40, 20, 11, 10, and
6 meter antennas. If I want to change bands, I have to replace each
antenna. Likewise, if I want to add a band, I have to buy more
antennas. I just want to simplify my operation for when I am mobile.
I have a 135 foot dipole with 300 ohm feed that I can toss up in the
trees for portable operation when I want to be efficient or for
emergency operations, but for moving, I don't want to pull off the
highway and get out of my car to change antennas every time I want to
change bands.

Thanks for the input.

Buck
--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

Buck wrote:
I have used a Hustler on 75 before. I was definitely
a weak signal station. I can only imagine that a tuned whip would
generate similar results, or more likely, poorer results.

Following are the summarized normalized combined results
of three 75m mobile antenna shootouts held in California
during the 1980's.

0 dB - (Reference) Bugcatcher or Screwdriver with large top hat

-2 dB - Bugcatcher or Screwdriver with no top hat

-5 dB - 8.5' whip with bugcatcher base loading coil

-6 dB - Bugcatcher with Stainless Steel Loading Coil

-8 dB - Hustler High Power system

-9 dB - Outbacker

-12 dB - Hamstick

-12 dB - 11.5' whip with SGC-230 autotuner

-14 dB - 8.5' whip with SGC-230 autotuner (estimated, not measured)
--
73, Cecil http://www.qsl.net/w5dxp

TT-247 and 102 whip for mobile antenna ?
 

Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual
loaded whips with varying results. The longer two piece unit worked
surprisingly well 80-10m years ago when conditions were better, even had
some fantastic 160m mobile contacts with it. The single 7ft version
lacks on 40 and especially 80m compared to the two piece whip but
compared to an unloaded 102” CB whip, it makes the CB whip look like a
dummy load on 40m and below. This is all with an SGC-230 feeding them.
Bob


Buck wrote:
On Sat, 29 Apr 2006 02:06:48 GMT, Bob wrote:

Not counting the potential tuner problems you mention, my experience is
a 102” whip with no loading will work ok on 10-20m, but on 40m and below
it sucks.
Bob

with no tuning? you get acceptable match to your rig without a tuner,
would you explain more?

thanks
Buck

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 07:55:47 -0400, Buck wrote:
There are a total of four antennas I have mentioned in here for
comparison sake.

Hi Buck,

They are by degrees poor, poorer and poorest.

The Hustler
You probably walked away from the best of the group here.
the 102 whip with a possible 2 foot extension
which isn't extension enough.
and two Antenna Specialists (AS)
the air-cooled resistors.

The fiberglass poles, of course, have copper wound around them
from bottom to top, above which is a whip (stinger) about the same
length as the pole.

These on something like 4 foot or longer extension poles would help
you for a cheap solution to the lower bands. Adding a top hat to the
stinger (yeah, impossible) would go further.

(I don't have the 102 whip yet.)

Get one, at hamfests they are cheaper than toilet paper.

I know others who have used the 102 steel
whip/auto-tuner combination that I have talked to never complained
that they only received s-2 signals with the system.

They would never notice on receive. The tuner made the difference.

Therefore, my
theory is that the winding of the coil on the fiberglass poles is
adversely affecting the radiation on out-of-band operation. I am
hoping that the steel whip, with or without the extension, will
perform better on all bands than any of these antennas tested.

A coil loading it halfway up would go further (AKA Bugcatcher).

I realize it is a compromise but the loss of an s-unit or two in
exchange for all band coverage for my mobile without having to switch
antennas or get out of the car and change taps is an acceptable
trade-off.

Then using a cheap tuner (with a loaded antenna), by all means, is
part of the solution.

My question is whether or not the tuner itself can hold up to
the task without being damaged.

As an all band solution, you do stand the risk of one of them being a
fire-breather. Just which is hardly predictable with any accuracy
given the vast number of variables. There is certainly a strong
correlation with longer wavelengths and short antennas. So, you might
design two systems - cheaply, of course.

Mobile quarterwave dipole?
base. The suggestion I was given was not to use the antenna tuner on
a 20 meter dipole to tune a 40 meter frequency. This would be a 1/4
wave dipole on 40 meters. I don't know what the impedance of such an
antenna would be, but I do know that a 1/4 wave vertical is a
reasonable match.

Again, you should never believe everything you hear.

A quarter wave dipole should be a snap to tune. On the other hand,
using an 80M antenna on 40M could be a bear. Also, a quarterwave
dipole is only vaguely related to a quarterwave vertical - um, let's
just say that relationship is too strained to be compared.

We never discussed the use of the tuner in the mobile.

That was the first thing you said, it would be quite close to the
proposed mount. Anyway, I have always considered it part of your
cheap solution and it has a place there.

I should have clarified that this statement. The internal inductor of
the tuner makes up the missing length of the antenna and heats up
which can cause damage to the antenna tuner's inductor. This is how
it was presented to me, or how I understood it. Again, the discussion
was using the tuner to tune short dipoles to transmit on lower
frequencies.

This is another instance of not believing everything - but it at least
this time it offers a nugget of truth. This is the spin of the wheel
of chance I mentioned above. Don't fret so much and simply try it in
the driveway. Open the tuner, fire up the rig and tune for lowest
SWR. Let go of the key and touch components to see how hot it's
gotten. You don't need infra-red analysis and toolkit of thermocouple
probes to obtain a good understanding of the situation. Repeat on all
bands.

73's
Richard Clark, KB7QHC

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 14:19:33 GMT, Cecil Moore
wrote:

Buck wrote:
I have used a Hustler on 75 before. I was definitely
a weak signal station. I can only imagine that a tuned whip would
generate similar results, or more likely, poorer results.

Following are the summarized normalized combined results
of three 75m mobile antenna shootouts held in California
during the 1980's.

0 dB - (Reference) Bugcatcher or Screwdriver with large top hat

-2 dB - Bugcatcher or Screwdriver with no top hat

-5 dB - 8.5' whip with bugcatcher base loading coil

-6 dB - Bugcatcher with Stainless Steel Loading Coil

-8 dB - Hustler High Power system

-9 dB - Outbacker

-12 dB - Hamstick

-12 dB - 11.5' whip with SGC-230 autotuner

-14 dB - 8.5' whip with SGC-230 autotuner (estimated, not measured)


Thank you, that is good to see.

--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

SNIP

This is another instance of not believing everything - but it at least
this time it offers a nugget of truth. This is the spin of the wheel
of chance I mentioned above. Don't fret so much and simply try it in
the driveway. Open the tuner, fire up the rig and tune for lowest
SWR. Let go of the key and touch components to see how hot it's
gotten. You don't need infra-red analysis and toolkit of thermocouple
probes to obtain a good understanding of the situation. Repeat on all
bands.

73's
Richard Clark, KB7QHC
Thanks, After reading all this, I will be going to get the antenna. I
have a mount on side of the van. i will re-wire it so it goes to an
SO-239 connector so I can mount the tuner next to the antenna for the
test. if all is well, I will get a hole kit and set it up on the roof.

I like the bug-catcher idea, but I don't have the parts :(.

Thanks, again,
Buck

--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote:

Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual
loaded whips with varying results. The longer two piece unit worked
surprisingly well 80-10m years ago when conditions were better, even had
some fantastic 160m mobile contacts with it. The single 7ft version
lacks on 40 and especially 80m compared to the two piece whip but
compared to an unloaded 102” CB whip, it makes the CB whip look like a
dummy load on 40m and below. This is all with an SGC-230 feeding them.
Bob

How long is the two piece whip?
--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 18:37:46 -0400, Buck wrote:

I like the bug-catcher idea, but I don't have the parts :(.

You don't have any WIRE? This is preposterous.

You split the vertical rise with an insulator and wind WIRE to fill
the gap. End of story. Your job is to make it mechanically sound at
70MPH and thumb your nose at what may be called Q here.

You want a bigger coil? Have dreams of that Q that marks status here?

Wrap a coffee can with several many wraps of paper so it clears all
seams and beads. Wrap turns of wire around the can/paper. Add epoxy
in nice neat lines along six lengths around the circumference (use
modeling or florist clay to build dams). Wait a couple of days for it
to cure. Take out the can and paper. Clean off the clay. Paint it
red, white, and blue!

What can 40 or 50 feet of wire, clay, three colors of paint, and an
ounce of epoxy cost? $5?

73's
Richard Clark, KB7QHC

TT-247 and 102 whip for mobile antenna ?
 

About 8 or 8 1/2ft.
Bob

Buck wrote:
On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote:

Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual
loaded whips with varying results. The longer two piece unit worked
surprisingly well 80-10m years ago when conditions were better, even had
some fantastic 160m mobile contacts with it. The single 7ft version
lacks on 40 and especially 80m compared to the two piece whip but
compared to an unloaded 102” CB whip, it makes the CB whip look like a
dummy load on 40m and below. This is all with an SGC-230 feeding them.
Bob

How long is the two piece whip?

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 16:32:50 -0700, Richard Clark
wrote:

On Sat, 29 Apr 2006 18:37:46 -0400, Buck wrote:

I like the bug-catcher idea, but I don't have the parts :(.

You don't have any WIRE? This is preposterous.

You split the vertical rise with an insulator and wind WIRE to fill
the gap. End of story. Your job is to make it mechanically sound at
70MPH and thumb your nose at what may be called Q here.

You want a bigger coil? Have dreams of that Q that marks status here?

Wrap a coffee can with several many wraps of paper so it clears all
seams and beads. Wrap turns of wire around the can/paper. Add epoxy
in nice neat lines along six lengths around the circumference (use
modeling or florist clay to build dams). Wait a couple of days for it
to cure. Take out the can and paper. Clean off the clay. Paint it
red, white, and blue!

What can 40 or 50 feet of wire, clay, three colors of paint, and an
ounce of epoxy cost? $5?

73's
Richard Clark, KB7QHC


LOL I haven't looked into that yet. I will. Thanks.


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

On Sat, 29 Apr 2006 23:49:31 GMT, Bob wrote:

About 8 or 8 1/2ft.
Bob

Buck wrote:
On Sat, 29 Apr 2006 15:40:50 GMT, Bob wrote:

Used various SGC tuners and Icom AH-4. Also tried both of SGCs dual
loaded whips with varying results. The longer two piece unit worked
surprisingly well 80-10m years ago when conditions were better, even had
some fantastic 160m mobile contacts with it. The single 7ft version
lacks on 40 and especially 80m compared to the two piece whip but
compared to an unloaded 102” CB whip, it makes the CB whip look like a
dummy load on 40m and below. This is all with an SGC-230 feeding them.
Bob

How long is the two piece whip?
Is there more to the two-piece than just two pieces? Is it a loaded
fiberglass whip with a stinger, or two solid pieces of wire making up
one long stinger. If so, the cb whip is longer, if you have a loaded
section, the loaded section is longer.

--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ?
 

I believe the SGC whip is continuously loaded with a tapered pitch over
a large diameter fiberglass core and also has a straight internal
shorter section for higher freqs. No top stinger, just big, thick, ugly
black heatshrink coated. I think it resonates around 13 and 22MHz. Look
up an SG-303 in Google.
Bob


Buck wrote:

How long is the two piece whip?
Is there more to the two-piece than just two pieces? Is it a loaded
fiberglass whip with a stinger, or two solid pieces of wire making up
one long stinger. If so, the cb whip is longer, if you have a loaded
section, the loaded section is longer.

TT-247 and 102 whip for mobile antenna ?
 

Ok, That makes sense


That gives me an idea. I wonder what stacking my 20 meter base on top
of my 40 meter base would produce. I'll try that today. I did some
testing, see my followup in this thread.

Thanks
Buck


On Sun, 30 Apr 2006 04:55:45 GMT, Bob wrote:

I believe the SGC whip is continuously loaded with a tapered pitch over
a large diameter fiberglass core and also has a straight internal
shorter section for higher freqs. No top stinger, just big, thick, ugly
black heatshrink coated. I think it resonates around 13 and 22MHz. Look
up an SG-303 in Google.
Bob


Buck wrote:

How long is the two piece whip?
Is there more to the two-piece than just two pieces? Is it a loaded
fiberglass whip with a stinger, or two solid pieces of wire making up
one long stinger. If so, the cb whip is longer, if you have a loaded
section, the loaded section is longer.




--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ? testing
 

Yesterday I bought the whip and put it on my existing ball mount on
the back left corner of my van. I still have the coax running to it
so there is about 20 feet of RG-58 (RadioShack brand) running from the
antenna to the tuner.

My preliminary results weren't good. It tunes all ham bands from 6
thru 17 easily. 20 starts getting finicky and the bands below seem to
cause arcing.

On the receive side, I am able to receive much better with the CB whip
than with either the 40 or 20 meter AS antennas on bands other than
what the AS antennas are designed for.

On transmit, things aren't so well. On 75 meters, I was able to hear
one person acknowledge that there was a mobile calling. I heard no
other response with any other band. Mind you, I was doing this from
just about sunset until about 11 PM with a long break for supper and a
short shopping trip. This wasn't the ideal time to test the antenna
for any band other than 40 and 80.

I heard some activity on 60 but no one responded to my call.

Today, if I don't get called into work, I plan to cut the wire next to
the antenna mount and install an SO-239 so I can wire the tuner
directly to the antenna or connect the coax to run to the front of the
van where I have the radio mounted.

I will test the antenna and try to compare it to the 40 and 20 meter
as antennas.

Just for kicks and giggles, I stacked the two antenna bases for 20 and
40 meters and added the steel whip to the top of the combo (that's
about 12 feet tall plus the height on the van.) The results weren't
good. The steel whip was too heavy and caused the antenna to bow to
the ground. I will try them today with and without the stinger to see
if that is a better combination than just the one band antenna. hmm,
20 + 40, that's 60 meters, right? lol.

It's 9 am here in Charlotte. I am going to read my email and go
experiment some more.

73 for now.


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ? testing
 

Buck wrote:
Today, if I don't get called into work, I plan to cut the wire next to
the antenna mount and install an SO-239 so I can wire the tuner
directly to the antenna or connect the coax to run to the front of the
van where I have the radio mounted.

SGC recommends that no transmission line be used between the
tuner and the antenna because of arcing. Consider that to
force just one watt into a CB whip on 4 MHz, EZNEC says it
takes over 1700 volts.
--
73, Cecil http://www.qsl.net/w5dxp

TT-247 and 102 whip for mobile antenna ? testing
 

On Sun, 30 Apr 2006 13:26:10 GMT, Cecil Moore
wrote:

Buck wrote:
Today, if I don't get called into work, I plan to cut the wire next to
the antenna mount and install an SO-239 so I can wire the tuner
directly to the antenna or connect the coax to run to the front of the
van where I have the radio mounted.

SGC recommends that no transmission line be used between the
tuner and the antenna because of arcing. Consider that to
force just one watt into a CB whip on 4 MHz, EZNEC says it
takes over 1700 volts.


Interesting. Thanks.

I am still testing. I tested with coax and the result is that the
antennas designed for a given frequency work much better on their
frequencies. I am looking for my soldering kit now for the
connectors.

I may try a direct connection to see what happens without coax if I
can.

back in a few.

n4pgw

--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ? test complete
 

I just finished testing my antennas. The result is that the
whip/tuner combination is unacceptable.

I took the coax off the ball mount and ran short wires, about 6 inches
from the center lead of the ball and from the ground screw at the ball
inside the cab of the van and ran them to the appropriate connectors
on the tuner. I then tested 75, 40, and 20 meters.

The test results were that I made no contacts on 75. The only thing I
heard was a very slow and long monolog on 3872 by some man who seemed
more to be broadcasting than talking to another individual. I waited
over ten minutes to see if he would break or identify, but he did
neither. I went to 3.915 and heard two stations go QRT, but received
no response when I called. I didn't have another antenna worth
testing on 75 so that concluded my 75 meter test. Results: NO JOY!

I went to 40 meters where I heard some conversations. It tuned up
more easily than on 75, but no one answered my calls. I swapped to
the 40 meter AS antenna and the stations I heard went from no signal
on the scale to over s-9. That was enough to resolve that test.
Results: NO JOY!

I went to 20 meters where I had more success. I talked to Jim on the
county hunter's net with the whip antenna. He was the only station I
was hearing at the time. I swapped to the 20 meter AS antenna and his
signal strength went from s-2 to s-9. Also, I was able to hear the
mobile that was running. Results: NO JOY!

I hooked the coax back up, setup the 20 meter AS antenna and tuned it
from the front of the car. I will not be drilling a hole and
rearranging all the roof antennas for the whip. I will rather focus
my attention on getting the rest of the parts of my screwdriver
together after I get paid next week and see if I can install it.

Thanks for all the comments.

If nothing else, all this testing did reveal a bad ground connection
from the coax to the cab of the van. It is now fixed.

73 for now.


--
73 for now
Buck
N4PGW

TT-247 and 102 whip for mobile antenna ? testing
 

I'd have never guessed.

"Buck" wrote in message
...


I tested with coax and the result is that the
antennas designed for a given frequency work much better on their
frequencies.