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Author Topic: Internal Tuners for Yaesu and Icom  (Read 386 times)

K3ZD

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Internal Tuners for Yaesu and Icom
« on: November 25, 2021, 06:33:51 PM »

Will the internal tuners on the latest Yaesu and Icom rigs handle digital modes without melting down?  Some guys say don't ever use an internal tuner for digital cuz they can't handle it.  I'm especially interested in the FT-991A or IC-7300. 
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K7LZR

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Re: Internal Tuners for Yaesu and Icom
« Reply #1 on: November 25, 2021, 07:25:28 PM »

Best thing would to use resonant antennas and therefore not need to use a tuner at all. But if you must, an external tuner such as that from MFJ, LDG, etc. would likely have a much wider matching range than the internal tuners in most radios.....
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W7XTV

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Re: Internal Tuners for Yaesu and Icom
« Reply #2 on: November 25, 2021, 08:46:12 PM »

Will the internal tuners on the latest Yaesu and Icom rigs handle digital modes without melting down?  Some guys say don't ever use an internal tuner for digital cuz they can't handle it.  I'm especially interested in the FT-991A or IC-7300.

I wouldn't use an internal tuner, other than with a beam, dipole (a 40 meter dipole should work on 15, for example), or other antenna with a known 50-75 ohm impedance on the bands you want to use.  They just don't have much range, although they should work at the rig's rated power output with the above criteria.

But the digital modes of today are no different than RTTY and SSTV, both of which have been around for decades:  Reduce your power output when running 100% duty cycle for more than a few seconds.  It doesn't matter if you're running a modern solid-state rig or a classic Collins, Drake, or Heathkit.  They weren't designed to run full power at 100% duty cycle.

I run FT8 on my Yaesu FT-450D, but I reduce the power to 50-60 watts and I turn the internal tuner off.  The latter is because I use a homebrew non-resonant (40 foot) Inverted-L with a 9:1 unun.  The internal tuner won't match it at all frequencies.  I use an external tuner which has a far greater matching range.
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He speaks fluent PSK31, in FT8...  One QSO with him earns you 5BDXCC...  His Wouff Hong has two Wouffs... Hiram Percy Maxim called HIM "The Old Man..."  He is... The Most Interesting Ham In The World!

AF5CC

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Re: Internal Tuners for Yaesu and Icom
« Reply #3 on: November 25, 2021, 09:18:41 PM »

I ran FT8 at 100 watts on a FT991 using its internal antenna tuner with no problems.  Same with an Icom 7300.

73 John AF5CC
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K6BRN

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Re: Internal Tuners for Yaesu and Icom
« Reply #4 on: November 25, 2021, 10:52:38 PM »

Hi John (AF5CC):

I've run 90 watts over many back to back FT8 QSOs into 2.5:1 VSWR with a Yaesu FT-991 and FTDX-3000 and their tuners have been fine.  The built-in tuners have limited range (up to about 3:1).  I have not had any problems with this.

But...  I haven't done it at 3:1 or at 100 Watts or both (I back off power a bit to ensure I stay out of the amplifier saturation zone) under similar circumstances.

The breaking point is probably different for each rig type and station setup (good airflow/poor airflow, hot environment/cool environment, higher SWR/lower SWR, higher power/lower power).

When in doubt, start out at lower power (25 watts) and work your way up, staying alert for any sign of stress (obvious chassis heating, odd smells, snap!  crackle! pop! sounds, etc.).

Best Regards,

Brian - K6BRN
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K6AER

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Re: Internal Tuners for Yaesu and Icom
« Reply #5 on: November 26, 2021, 01:11:39 AM »

The radio internal tuners will handle about a 3:1 ratio or 17 to 150 ohms. That is not much range and even a resonate dipole will encounter limits on the internal radio tuner at band edges. I don’t use my radio (7300) tuner. I have an external tuner that can cover 10-1800 ohms impedance.

My go to antenna is a non-resonate, 200-foot dipole with 450 ohm ladder line coming to a 1:1 choke balun and then LMR-400 coming into the ham shack.  My radio drives an OM-2000 with the antenna feed adjusted through a 2000 watt antenna tuner. The Key is to have an antenna with under 300-ohm impedance on the bands of interest. For me this is 17-80 meters. I have checked the antenna tuner (much modified Palstar AT2KD) for hot spots with an inferred thermometer. High current areas such as the band switch and the grounded end of the rotary coil will be the first to heat up in high power applications.

Manufactures will label antenna tuners as 1500 watt units but under normal application you will find some of the designs offered are only good for 800 watts key down and then for less than 30 seconds..

Good Luck, Mike K6AER
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LA9XNA

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Re: Internal Tuners for Yaesu and Icom
« Reply #6 on: November 26, 2021, 01:23:55 AM »

Most ham rigs is not designed to run 100% duty cycle. This is usually mentioned int the manual. A good rolle of tumb is to run the rig at the same power level as the rig would run in AM. AM is in many ways similar to digimode when one look at duty-cycle because the PA transistors are running full modulation the whole time when transmitting.
When sending SSB(voice) and CW the transistors will only have a duty-cycle of about 30% and this will reduce the heating of the transistor and output network like filters and tuner.
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K0UA

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Re: Internal Tuners for Yaesu and Icom
« Reply #7 on: November 26, 2021, 05:49:39 AM »

But the 7300 WILL run FT8 at 100 watts for years.  I have been doing just that very thing since June of 2017 when FT8 came on the scene and running JT65 and JT9 since 2016 when I got my first 7300.  The rig does NOT overheat, period, full stop. I have tried. I don't believe it can be done. The temp gauge never get beyond the letter L in the word COOL, and that is a long way from the word HOT.  The case of the rig actually stays cool and the only warm spot on the rig is the temprature of the air flowing out the fan port. Yes, most rigs will overheat if your run FT8 continuously at 100 watts with them. I used to run MSK144 with my old Icom 756 pro III chasing meteor scatter on 6 meters, and after a long run (say 15 to 20 minutes) it would usually take 30 minutes for the rig to cool down with its fans on high. So I stopped running 100 watts with it. The rig just got too hot. The 7300 will run for as long as you want to run at 100 watts on any digital mode and it will NEVER get hot in the first place and has ZERO cool down time. It is uncanny how cool that rig stays.
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73  James K0UA

KA4DPO

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Re: Internal Tuners for Yaesu and Icom
« Reply #8 on: November 26, 2021, 07:49:37 AM »

Will the internal tuners on the latest Yaesu and Icom rigs handle digital modes without melting down?  Some guys say don't ever use an internal tuner for digital cuz they can't handle it.  I'm especially interested in the FT-991A or IC-7300.

And that is because some guys don't have a clue about what they are doing. 

The internal tuners are only designed to provide a match for 3:1 or less, not much.  It will allow you to use a resonant dipole, cut for the center of the 80 meter band, from 3.5 to 4.0 MHZ. 

If you use an external tuner, you can run digital modes till the cows come home.
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KK2DOG

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Re: Internal Tuners for Yaesu and Icom
« Reply #9 on: November 26, 2021, 08:34:49 AM »

If I'm not mistaken, Icom's have a 100% duty cycle rating.
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K4KRW

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Re: Internal Tuners for Yaesu and Icom
« Reply #10 on: November 26, 2021, 08:54:02 AM »

If you use an external tuner, you can run digital modes till the cows come home.

If you buy an external matching unit, make sure you read the manual before buying.  The manual should detail the operating limits.  If it doesn't, I would not buy it.  For example, for my LDG

1.8 to 54.0 MHz coverage.
Tunes 6 to 1000 ohm loads (16 to 150 on 6M),
.1 to 125 watts SSB and CW peak power, 30 watts on PSK and digital modes, and 100 watts
on 6 meters.

So this '100 Watt' tuner is limited to as low as 30 watts depending on mode.

Richard
K4KRW



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K0UA

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Re: Internal Tuners for Yaesu and Icom
« Reply #11 on: November 26, 2021, 10:16:11 AM »

If you use an external tuner, you can run digital modes till the cows come home.

If you buy an external matching unit, make sure you read the manual before buying.  The manual should detail the operating limits.  If it doesn't, I would not buy it.  For example, for my LDG

1.8 to 54.0 MHz coverage.
Tunes 6 to 1000 ohm loads (16 to 150 on 6M),
.1 to 125 watts SSB and CW peak power, 30 watts on PSK and digital modes, and 100 watts
on 6 meters.

So this '100 Watt' tuner is limited to as low as 30 watts depending on mode.

Richard
K4KRW

My LDG manual says the exact same thing. 30 watts for digital modes for an external tuner rated at 125 watts SSB. Can you run 100 watts thru it on FT8?  Yes for SOME loads and definitely NOT for others. Don't ask me how I know this.
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73  James K0UA

WA9FZB

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Re: Internal Tuners for Yaesu and Icom
« Reply #12 on: November 26, 2021, 12:47:50 PM »

I don't want to get into the old battle of how to calculate duty cycle for digital modes, so won't go there. . .

But I do sometimes run my TS-590 at 100 watts on FT modes (into a resonant trap vertical) with no issues related to cooling.  Before I got into digital operation, I called Kenwood tech support and asked them if the published rating of 100 watts on FM also applied to digital modes.  The technician I spoke with said, "Sure.  We run those rigs wide open for hours.  That's what fans are for."

In actual use, my rig rarely ever runs its fans during FT operating periods.  Yes, if I pound on it for many cycles over a long operating session, the fans will switch on for a couple of minutes, but then they switch off.  For my normal "search and pounce" digital operation, I never hear fans at all.

So, the advice to only run the rated AM power levels may not apply universally.  If a rig is rated at full power (say, 100 watts) on FM, that is a 100% duty cycle, and thus that same rig should be able to sustain similar operating conditions on digital modes without damage.  Absent a similar rating for any 100% duty cycle mode, it is prudent to start at the AM rating and try higher levels, watching for unwanted behaviors such as heavy cooling fan usage.

I would imagine that if we looked at the rigs of different manufacturers in detail, we would find that each manufacturer has a different mindset as to how their rigs should be used.  With respect to digital operation, that is probably similar to the common question of whether a rig should show any ALC current or not.  Again, the answer is not the same for all brands of rigs.  Kenwood, for example, recommends that digital users run a small amount of ALC, but definitely greater than zero.  Other brands of equipment are best used with zero ALC.
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KA4DPO

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Re: Internal Tuners for Yaesu and Icom
« Reply #13 on: November 26, 2021, 01:01:38 PM »

If I'm not mistaken, Icom's have a 100% duty cycle rating.

The ALC will begin to fold back the power when the load impedance exceeds 75 ohms, this is to protect the finals.  Anything between 47 and 75 ohms will allow full output.
« Last Edit: November 26, 2021, 01:07:40 PM by KA4DPO »
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KA4DPO

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Re: Internal Tuners for Yaesu and Icom
« Reply #14 on: November 26, 2021, 01:06:25 PM »

If you use an external tuner, you can run digital modes till the cows come home.

If you buy an external matching unit, make sure you read the manual before buying.  The manual should detail the operating limits.  If it doesn't, I would not buy it.  For example, for my LDG

1.8 to 54.0 MHz coverage.
Tunes 6 to 1000 ohm loads (16 to 150 on 6M),
.1 to 125 watts SSB and CW peak power, 30 watts on PSK and digital modes, and 100 watts
on 6 meters.

So this '100 Watt' tuner is limited to as low as 30 watts depending on mode.

Richard
K4KRW

I didn't say anything about auto tuners.  Any good manual tuner rated for 1.5 KW will do the job nicely.  I don't care for auto tuners because so many of them are input power limted depending on duty cycle.  The ones that aren't cost a lot more than a really great manual tuner that can handel much greater power. 

I do use a couple of AH-4's for portable work, but I fully understand their limitations.   
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