External Auto Antenna Tuner

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I have a external Auto Antenna tuner at the base of my Antenna. I can set my FLEX transmit TUNE power to 1 Watt and auto tune my antenna using this external tuner. Is there any issues with running my FLEX iRF antenna in BYP vice ATU. This antenna is cut for multiple HAM BANDS. However, If I attempt to use this antenna on other than HAM Frequencies, any use of the FLEX internal Antenna Tuner (ATU) gives the  FLEX  HIGH SWR alarm.  If I bypass (BYP) the FLEX ATU, using 1 Watt,  I can tune the outside antenna with the external tuner to get very low SWR on multiple frequencies external to HAM bands.  (MARS and FEMA nets).
Question: Will I damage my FLEX using the BYP and the external tuner?
Thanks  Bill W4EY
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W4EY

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Posted 5 years ago

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Tim - W4TME, Customer Experience Manager

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If you have an antenna tuner (more precisely an antenna coupler if the connection to the antenna is balanced) at the base of your antenna, you should not use the internal ATU in the radio.  Your remote antenna coupler, when tuned, should be presenting a 50 ohm load on the coax to the PA and based on your description, it is doing exactly that when in the radio's ATU is operating in BYPASS mode.

This is exactly how I have run all my FLEX radios that have an internal ATU (1000, 3000, 5000 and 6500) for the last 9 years and it never adversely affected the the internal ATU in the radios.
(Edited)
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W4EY

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Tim: Last question on this. Can I use one of the FLEX 6500 ACC pins or TX Relay RCA Jacks to key an External Automatic Tuner. The external tuner can be keyed into Tune state with Tune signal from the Radio.

Thanks

Bill

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Tim - W4TME, Customer Experience Manager

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You may be able to use the TX Relay jack.  Mine uses low level RF so it does not need to be keyed.
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W4EY

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Tim Thanks.  Yes my tuner is mounted ground level at the base of my Loop. It is the older technology that requires a TUNE (Relay) action to put it in TUNE. It will Auto with RF applied, However, There is a delay across the COAX until the tuner starts the actual tuning process.  This is mainly due to the Relays in this unit.
73's Bill

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Ken - VE5KC

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Hi Tim,

I'm getting close to ordering a 6300 or 6500..  Still doing a lot of reading, partly to figure out how it will fit in with my setup..  The computer part is no problem, just understanding how some features work.

I use either LDG or MFJ tuners with RF sensing. I need a 5 -10 watt carrier for them to tune.

Can you please set me straight on how you use your external tuner.

Does the software have provision to set the tune power and use the tune button with an external tuner?

TNX..  73 ..  Ken - VE5KC
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George Molnar, KF2T, Elmer

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I use an MFJ tuner at my feedpoint. The TUNE power is set and saved in my 6500 to provide an appropriate level for sensing and tuning. Operating power is stored separately. All happens in the profile settings. No relay closure necessary with the MFJ. Works like a champ.
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KY6LA - Howard, Elmer

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While I do not use an external auto tuner (I own a SteppIR - which changes with frequency so it is always in tune),

YES.. there is a Tune Power Setting and Yes there is a TUNE Button.

I actually use the TUNE Button to drive my AMP when I am Setting it to its Power input limits..
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Ken Crowston

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Thank you for the fast reply.

I am very restricted in what I can have for antennas and rely on my tuners for all band operations.

73.. Ken - VE5KC