So on my Yaesu FT-710, I set it up with the MFJ-939 with the appropriate Yaesu interface cable.  Set the radio to use the external instead of the internal tuner.  I was hoping it would be as simple as hitting the tune button on the front of the radio as I would with my IC-7200 and LDG IT-100 tuner.  No such luck.  The tuner will power on with the radio but hitting the tune button on the FT-710 does nothing.  Well, it just gives me three rapid beeps.  If I press and hold the tune button it will give me two quick beeps after one second.

Now then, if I put the rig into CW mode and key the mike it'll send a tone that the tuner will pickup and tune to.  Well, most of the time.  Sometimes I've got to turn the tuner off then back on, then key the mike before it will start automatically tuning.  

Don't know if anybody else running the FT-710 has seen this behavior with an external tuner.  Maybe it's different and works as it should with the LDG?  For some reason I'd thing LDG would have gotten it right and it's just an MFJ thing.

On the plus side, the 939 is a very quick tuner when it comes to tuning a frequency it already has in memory.  Just a click and it's done.  Now if it doesn't have a frequency or needs to do a full re-tune, it takes considerably longer than my LDG did on the 7200.  But the MFJ also has a much broader tuning range.  Can even get a match for my 40M OCFD to 80M even.  I know, I know, it still is inefficient, but it kinda sorta works.  The LDG looked at it and just said: Nope!

This is a well documented bug with the Yaesu FT-710 and currently there is no work around for the one button tuning solution with the MFJ 939 auto-tuner. MFJ claims that Yaesu changed something with the design of the FT-710 disabling users from controlling the MFJ 939 with the "TUNE" button on the radio. The only tuner that works with the FT-710 is the Yaesu FC-40 remote tuner, but it has a very poor matching range compared to the MFJ 939.

To use my MFJ 939 tuner with the Yaesu FT-710, I set my RF power output to 5 to 10 watts on AM mode and leave it there as my default setting. I then use the "Sticky Tune" feature of the MFJ 939 tuner to adjust the tuner. I use the MFJ-5114Y cable to power the tuner from the radio, but you can skip using that cable and power the tuner separately via the tuner's 12 volt jack.

To tune my antenna I make sure that both the Yaesu FT-710 and MFJ 939 tuner are powered on.  I then push and hold the white "TUNE" button on the MFJ 939 tuner until it beeps. I release the tune button and key the microphone on the FT-710 while on AM mode until the MFJ 939 completes it's tuning cycle.  Once completed I can then switch back to whatever mode I originally wanted to use and start transmitting.

Just remember that you will have to switch back to AM each time you need to retune when changing bands or if stray too far from your original frequency.

It's a clunky solution, but it works every time on all bands.  YMMV

Similar to what I've been doing, change over to CW and key the mike.  The 939 will then click and be done, assuming a freq in memory.  But I like your AM method as you mentioned since the output power can be set lower for that mode.  Good for longer tuning sequences and I'm not sending out a 100W CW tone unless I spin the power down then back up when switching to SSB since CW follows the SSB power output setting.

I use AM to tune because it’s not a mode I ever typically use.  The Yaesu FT-710 remembers my drive setting for AM when I change bands and think the lower drive is easier on the components of the MFJ tuner during tuning. YMMV  

Hopefully, Yaesu can put out a firmware update that fixes this.

 

Yaesu also made some undocumented changes to CAT control in the FT-710 that are problematic for some, but when pressed Yaesu claims there is "NO" problem.   The "Big Three" Japanese manufacturers are painfully slow when it comes to addressing firmware updates and seem somewhat tone deaf when it comes to addressing user complaints or suggestions.

I use the AM mode set to 5 watts for my FT891 and My little tarheel II screwdriver tuning. Yes I have a controller that gets it in the ballpark, but those that have run mobile know the SWR moves around as you travel, depending the type of ground you are over, and will need touching up from time to time away from the presets in the controller. AM mode is perfect for this as it is as far as I am concerned a "throw away" mode that I don't use, and can afford to leave set down to the low level so I don't have to dive into the menu to adjust some other mode like CW. It works well.

The antennas I'm using on the 710 are 3.5:1 or better so the internal tuner is sufficient.

I have a LDG Z-11 and AT100ProII tuners for the 891 for tuning doublets in the field and with LDG interface cable it's seamless.

Has anyone tried the 710 with a "straight" TRS cable?  I can try tonight for S&Gs.

Hmm. I just use. The dx10 settings in FLrig/ FLdigi and it worked the first time. This was after the last firmware update so maybe Yaesu addressed it?

I think Groups.IO has a few posts about the still unresolved CAT issues, but I'm extremely happy with the FT-710. The March 2023 firmware update and completing the MARS mod has made the radio my daily driver.

The DNR is excellent after the update and it's almost on par with the FTDX-10. It handles my local noise issues with ease and has made using SSB enjoyable.

The LDG Yaesu interface cable works just fine between the AT-100ProII and Z-11 tuners and the 710...

Set the tuner to in the menu to Linear and external.

Pressing the Tune button on the tuner triggers a ~10W carrier and it tunes right up, and fast.

Pretty much figured it was an MFJ problem.  So something of a tradeoff--The MFJ tuner can handle more power for digital modes and has a wider matching range.  The LDG works with the one button tune.

This works with just about anything, it's not automatic, but will tune a wet noodle.

I got one of these when I was a new ham.

I talked to Florida on 10m on a 100watt lightbulb.

I also loaded up an aluminum ladder and talked on 20m.

Does the FT-710 have an SWR check function?  

I know my FT-450D does.  You can assign a button to check the SWR, and it will transmit and display the SWR the entire tine you hold the button, and then return to normal operation when you release it.

I haven't connected an external wattmeter to see whether the radio reduces power for the check, but I imagine it probably does.

If the 710 has this function, you might be able to tune a little more conveniently than manually reducing power and changing your mode, then changing it all back.  This assumes also there isn't a timeout programmed into the SWR check function that would shut it off before your tune cycle completes.

Setting the AM mode to 10W (set it and forget it) then quickly switching to it and hitting the PTT will quickly bring the tuner in line.  Most the times it's hit the PTT and the tuner just goes click and it's done, assuming the freq had been used before and is in memory.  Switching back to U/LSB and it will go to the configured 100W output.  

The other option is to tune in CW mode.  Pressing the PTT will send a CW tone, but the CW power setting follows the SSB setting.  Granted the rig will fold back power if it sees a high SWR.

The rig does warn of high SWR on the display.

Okay thanks for the info.  I'm considering making one of these radios a gift to myself this Christmas.

I downloaded the manual and searched it for "SWR" and didn't see a check function like my 450D has.