[SECC] Testing The Internal Tuner in your Radio

[Jerry Flanders]

He might have expected it to load his bedsprings on 160 M like some 
of he better external tuners can do.

ICOM specs the tuner to only handle 17 - 150 Ohm loads (3:1 SWR). One 
way to verify ATU operation is to use three 50 ohm dummy loads, first 
connected in series, then in parallel. Just check it on all bands to 
see if it can cope.

Jerry W4UK

At 10:46 PM 1/25/2011, Jeffrey Clarke wrote:
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>Hi All,
>
>I sold a radio to this guy (my IC756PRO) and the day it's delivered 
>to him he calls and tells me the internal antenna tuner in the radio 
>is not working right. He was unwilling to have someone look at it at 
>his own cost (he wanted me to pay for that) so I told him to send 
>the radio back to me and I refunded his money.
>
>I got the radio back tonight an hooked it up.  I have 160 , 40 and 
>20 meter antennas that are cut for the CW bands. The SWR is higher 
>in the phone parts of the band.  The internal tuner worked just fine 
>when I turned it on the tune out the slight mismatches in the higher 
>parts of those bands.  I also hooked up my 135 foot zepp with 450 
>ohm feeder line to a DX Engineering 4:1 balun and went directly to 
>the radio on the 50 ohm side of the balun. I was able to get the 
>antenna to tune across the whole 80 meter band.  I wasn't able to 
>get it to tune with that setup on 20 meters. I would imagine the 
>impedance is more complex using that antenna on 20 meters and up.
>
>I'm trying to determine if I really have a problem with the internal 
>tuner.  This guy supposedly hooked the radio directly to a dummy 
>load to test the internal tuner. Is this really a good test ?
>
>
>Thanks, Jeff  KU8E
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