The AM Forum

THE AM BULLETIN BOARD => Technical Forum => Topic started by: AE1CT on March 08, 2013, 10:26:02 PM



Title: ANT TUNER
Post by: AE1CT on March 08, 2013, 10:26:02 PM
I HAVE MY HT-37 AND MY SX-111 UP AND RUNNING, WILL MY MFJ-986 T-TUNER WORK ON THE AM FREQS, I KNOW IT WILL BUT, I WAS TOLD THAT I HAVE TO USE A TUNER MADE FOR JUST AM, LIKE A VIKING MATCH BOX?? IVE NEVER HEARD OF A TUNER MADE FOR JUST AM. RF IS RF, THE TUNER DOESNT CARE IF ITS AM OR SSB, AM I RIGHT OR SHOULD I GO BACK TO RADIO SCHOOL!!


Title: Re: ANT TUNER
Post by: N2DTS on March 08, 2013, 10:38:45 PM
MFJ....3kw tuner, its likely good for 100 watts of AM...


Title: Re: ANT TUNER
Post by: Steve - K4HX on March 08, 2013, 10:40:59 PM
It's about power handling capability. AM has a much higher duty cycle than SSB or CW. So the average power seen by the tuner is much greater on AM. More than one tuner that never showed any heating on SSB has melted when used on AM.

But, if you are using a barefoot HT-37, your MFJ 986 should be OK. Make a transmission and check for any heating. If there is none, you are good to go.


Title: Re: ANT TUNER
Post by: AE1CT on March 08, 2013, 10:47:49 PM
CAN YOU RECOMEND A TUNER THAT WILL WORK WITH ABOUT 200 WATTS CONTINUOUSLY ON AM?


Title: Re: ANT TUNER
Post by: Steve - K4HX on March 08, 2013, 11:39:31 PM
Either of the Johnson Matchbox tuners, one rated at 275 watts and the other at 1 kW AM.

Lots of tuner info in the spreadsheet at the link.


http://dj0ip.de/antenna-matchboxes/matchbox-shoot-out/


Title: Re: ANT TUNER
Post by: n1uvi on March 09, 2013, 08:57:08 AM
I use the very same tuner the MFJ 986 T
with an HT 37 driving a home brew amp w 4 811's
to a balanced line feeding an 80 meter dipole
works great with 400 to 600 watts PEP

the 986 T has a 3KW input rating
will do 1000 Watts PEP no problem
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