Flex Auto Tuner

Arizona Mike

I noticed that the Flex 6700 has a built in tuner with a 10:1 range except on 160 and 6m.

This range would be really helpul for full wave 80m loop with 4:1 balun used the other bands. Anyone know why this tuner was not incorporated into the 8000 series radios?

Geoff AB6BT

The 8000 series ATU wil match 8.3 - 300 Ohms acording to the Hardware Manual.

Arizona Mike

Thanks, appreciate the answer. The websitre indicated 3:1 so I was confused,

Geoff AB6BT

No Problem, you're welcome.

VE7ATJ_Don

Hi Mike… I'm interested as to where you saw that the 6700 had a 10::1 ATU. According to the Flexradio.com site, in the 'Full Specs' for the 6700, there is the following:

I have a 6700 and make full use of its very capable ATU with my 43' vertical (yes, it will tune it to 160m and 6m and everything in-between), but I'm pretty sure it's no where near 10::1 capable.

And, as far as I know, the ATU in the 800 series is identical to the one in the 6000's.

Arizona Mike

Hello Don,

Saw it here on the bottom of the page:

https://www.flexradio.com/products/certified-pre-loved-flex-6700-signature-series-sdr-transceiver/?srsltid=AfmBOor_CwNf6fG_e4A6dqGDfdweomnhJH6ISuSjnT4GQYxHM1BaraUr

"The FLEX-6700 provides continuous duty 100W output across the entire 160-6m band. The FLEX-6700 also includes an automatic antenna tuner (ATU) capable of tuning antennas over 10:1 range (3:1 on 160m and 6m)."

Arizona Mike

Can anyone confirm that the 6700 antenna tuner is really a 10:1 tuner except on 160m and 65m? I ask because using a full wave 80m loop for ALE Scanning, some of the frequencies have an SWR of 4:1 up to 6:1.

Mike-VA3MW

The ATU in all FlexRadios (and most HF) radios have a published range of 3:1. They are designed to extend the range of a already resonate antenna.

Does it mean that it will tune above 3:1? Possibly and that will then show a 50 ohm (ish) load to the radio and make the radio happy. However, that does not guarantee that a lot of RF energy might be turned into heat and not actually radiated by the antenna.

If you need a tuner that tunes beyond 3:1, you may need a invest in an external tuner that handles a much broader range.

If you are just scanning and not transmitting, you can safely bypass actually the use of the internal ATU.

Dan-N7HQ

I'm curious why an ATU that can achieve a match with a 10:1 load is perceived as somehow more attractive over one that does not? That is a serious question… what is the use case?

73,
Dan

Geoff AB6BT

Mike-VA3MW…

Then what does this mean: "The 8000 series ATU will match 8.3 - 300 Ohms" acording to the Hardware Manual.???

Arizona Mike

I am totally confused………not all that rare or surprising.

The Flex advertisement seems to be clear and unambiguous.

"The FLEX-6700 provides continuous duty 100W output across the entire 160-6m band. The FLEX-6700 also includes an automatic antenna tuner (ATU) capable of tuning antennas over 10:1 range (3:1 on 160m and 6m)."

Seriously, can Flex answer if the 6700 ATU tune 10:1 or not? And, if not was the ad wrong?

Arizona Mike

Dan wrote: "I'm curious why an ATU that can achieve a match with a 10:1 load is perceived as somehow more attractive over one that does not? That is a serious question… what is the use case?

73,
Dan"

To answer you question,

Someone using a full wave loop antenna with a 4:1 balun wishing to operate on certain frequencies would need a tuner capable of tuning an SWR in excess of 3:1. An example might be MARS frequencies that are above or below the Amateur frequencies.

Mike-VA3MW

It is possible that the ATU range on the documentation is in error for the FLEX-6700. At this time we have no way to go back and confirm if that was accurate.

Feel free to give it a try and if it works for you, then perfect.

If you are thinking of purchasing a Pre-Loved Unit, you can test it on your own antennas and see if it works. If not, then you can return the radio for a refund if you wish.

Tuners are not an exact science. I have seen cases where my internal tuner will present a successful result and my LDG will not on the same antenna. YMMV.

Arizona Mike

Thank you sir.

Mike-VA3MW

Let me add a correction to this.

It turns out that we have been advertising the FLEX-6700 with this message since about Day 1 back in 2012 or so and is correct.

I had lumped all internal ATU's into a simple 3:1 range. That is not true with the 6700.

Arizona Mike

Thank you sir, appreciate the investigative 😀 work.

VE7ATJ_Don

So Mike.. are you saying the ATU in the 6700 is different from the ones in the other 6000's and the 8000's?