"Jeff Liebermann" wrote in message
...

On Sun, 05 Jul 2015 20:22:19 +0100, Brian Reay wrote:

As for a simpler way, I'd recommend a remote auto-matcher like an SGC at
the antenna base. It will minimise coax losses and should give you a
good match, at least for most bands. I've used a similar set up (with
radials) and achieved a good match even on 80m.

If your radio has a built in tuner, then it can be used to 'tweak' the
match in the event the radio isn't 'seeing' 1.5:1. Turn it off
initially. Let the SGC find a match. If it isn't ideal, use the local
ATU for a final tweak. I never found this was required but YMMV.

Not everyone is a true believer in antenna tuners:
http://www.qsl.net/g3tso/Hombrew-Mobile%20Antennas.html


Interesting.
I'm off on a different approach.

I have an RF ammeter mounted in a box. The box is in the shack between the
ATU and the antenna.

I simply adjust the ATU for max current on the ammeter.

On Sun, 5 Jul 2015 17:08:56 -0700, "Wayne"
wrote:
I'm off on a different approach.
I have an RF ammeter mounted in a box. The box is in the shack between the
ATU and the antenna.
I simply adjust the ATU for max current on the ammeter.

Rewind. I just noticed that you're planning to put the RF ammeter
between the ATU and the antenna. That will work, but with
approximately 1200 ohms antenna impedance, you are going to see
50/1200 = 0.04 times the antenna current that you would see on the 50
ohm line between the xmitter and the ATU. If you're running lots of
power, that might work, but offhand, methinks not.

Also, you can't adjust the ATU for maximum current. It adjusts itself
based on it's own internal VSWR sensor. All you can do is watch the
light show and listen to the relays clatter. You might be able to
have some control if it were a motorized antenna tuner. Certainly a
manual antenna tuner would work.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...

On Sun, 5 Jul 2015 17:08:56 -0700, "Wayne"
wrote:
I'm off on a different approach.
I have an RF ammeter mounted in a box. The box is in the shack between
the
ATU and the antenna.
I simply adjust the ATU for max current on the ammeter.

Rewind. I just noticed that you're planning to put the RF ammeter
between the ATU and the antenna. That will work, but with
approximately 1200 ohms antenna impedance, you are going to see
50/1200 = 0.04 times the antenna current that you would see on the 50
ohm line between the xmitter and the ATU. If you're running lots of
power, that might work, but offhand, methinks not.

Also, you can't adjust the ATU for maximum current. It adjusts itself
based on it's own internal VSWR sensor. All you can do is watch the
light show and listen to the relays clatter. You might be able to
have some control if it were a motorized antenna tuner. Certainly a
manual antenna tuner would work.

This isn't something planned. I have been using the ammeter between the
tuner and antenna for many years.

With an automatic tuner, there is no feedback from the ammeter to the tuner.
In that case it is simply an indicator that current is present.

Some of my antennas have SWR outside the capabilities of my automatic tuner.
A manual tuner is used in that case.

With a manual tuner, I don't look for a specific reading, just a peak in the
current from the tuner to the antenna.

On 7/5/2015 7:08 PM, Wayne wrote:


"Jeff Liebermann" wrote in message
...

On Sun, 05 Jul 2015 20:22:19 +0100, Brian Reay wrote:

As for a simpler way, I'd recommend a remote auto-matcher like an SGC at
the antenna base. It will minimise coax losses and should give you a
good match, at least for most bands. I've used a similar set up (with
radials) and achieved a good match even on 80m.

If your radio has a built in tuner, then it can be used to 'tweak' the
match in the event the radio isn't 'seeing' 1.5:1. Turn it off
initially. Let the SGC find a match. If it isn't ideal, use the local
ATU for a final tweak. I never found this was required but YMMV.

Not everyone is a true believer in antenna tuners:
http://www.qsl.net/g3tso/Hombrew-Mobile%20Antennas.html


Interesting.
I'm off on a different approach.

I have an RF ammeter mounted in a box. The box is in the shack between
the ATU and the antenna.

I simply adjust the ATU for max current on the ammeter.

Hey, Wayne -

As a matter of curiosity on my part, can you find a way to measure the
ammeter's resistance and let me know the full-scale value?

Many thanks,
John

"John S" wrote in message ...

On 7/5/2015 7:08 PM, Wayne wrote:


"Jeff Liebermann" wrote in message
...

On Sun, 05 Jul 2015 20:22:19 +0100, Brian Reay wrote:

As for a simpler way, I'd recommend a remote auto-matcher like an SGC at
the antenna base. It will minimise coax losses and should give you a
good match, at least for most bands. I've used a similar set up (with
radials) and achieved a good match even on 80m.

If your radio has a built in tuner, then it can be used to 'tweak' the
match in the event the radio isn't 'seeing' 1.5:1. Turn it off
initially. Let the SGC find a match. If it isn't ideal, use the local
ATU for a final tweak. I never found this was required but YMMV.

Not everyone is a true believer in antenna tuners:
http://www.qsl.net/g3tso/Hombrew-Mobile%20Antennas.html


Interesting.
I'm off on a different approach.

I have an RF ammeter mounted in a box. The box is in the shack between
the ATU and the antenna.

I simply adjust the ATU for max current on the ammeter.

Hey, Wayne -

As a matter of curiosity on my part, can you find a way to measure the
ammeter's resistance and let me know the full-scale value?

No, I don't have enough test equipment to easily do that.

With a DVM it measures 0.4 ohms and with a VOM measures 28 ohms. And the
VOM gives no needle movement.

It is a O. D. McClintock Signal Corp typs I S-III with full scale of 2.5
amps.
Since it was salvaged from some WW II equipment back in the 1950s, it
probably isn't calibrated.

But, it gives a useable relative reading.

On 7/7/2015 10:14 AM, Wayne wrote:


"John S" wrote in message ...

On 7/5/2015 7:08 PM, Wayne wrote:


"Jeff Liebermann" wrote in message
...

On Sun, 05 Jul 2015 20:22:19 +0100, Brian Reay wrote:

As for a simpler way, I'd recommend a remote auto-matcher like an
SGC at
the antenna base. It will minimise coax losses and should give you a
good match, at least for most bands. I've used a similar set up (with
radials) and achieved a good match even on 80m.

If your radio has a built in tuner, then it can be used to 'tweak' the
match in the event the radio isn't 'seeing' 1.5:1. Turn it off
initially. Let the SGC find a match. If it isn't ideal, use the local
ATU for a final tweak. I never found this was required but YMMV.

Not everyone is a true believer in antenna tuners:
http://www.qsl.net/g3tso/Hombrew-Mobile%20Antennas.html


Interesting.
I'm off on a different approach.

I have an RF ammeter mounted in a box. The box is in the shack between
the ATU and the antenna.

I simply adjust the ATU for max current on the ammeter.

Hey, Wayne -

As a matter of curiosity on my part, can you find a way to measure the
ammeter's resistance and let me know the full-scale value?

No, I don't have enough test equipment to easily do that.

With a DVM it measures 0.4 ohms and with a VOM measures 28 ohms. And
the VOM gives no needle movement.

It is a O. D. McClintock Signal Corp typs I S-III with full scale of 2.5
amps.
Since it was salvaged from some WW II equipment back in the 1950s, it
probably isn't calibrated.

But, it gives a useable relative reading.

Many thanks for the info. The reason I asked was that I thought it might
be possible to build one. I need a starting point.

Again, thanks.