[SECC] Testing The Internal Tuner in your Radio

[Michael Almeter]

I'll second Jim's comment,     Kenwood internal tuners can tune nearly anything. It was a real shock when I bought my FT-1000MP, and found that there were some antennas I just couldn't tune anymore, that were easy with my TS-570D.      The answer to the problem was really simple... improve the antenna farm with matching networks and baluns to get everything to 50 ohm by the time it reaches the shack. The end product was great... instant band switching during contests. 73,Mike 

W4MJA

--- On Wed, 1/26/11, Jim Worthington <jimworth at me.com> wrote:

From: Jim Worthington <jimworth at me.com>
Subject: Re: [SECC] Testing The Internal Tuner in your Radio
To: "SECC SECC Reflector" <secc at contesting.com>
Date: Wednesday, January 26, 2011, 8:36 AM

The results of your tests are normal for an internal tuner. I would try a 50 ohm dummy load to see if you can reproduce the problem your buyer had. The tuner should be able to match 50 ohms on all bands in addition to the 3:1 loads  that Jerry suggested.

The range of internal tuners varies considerably by manufacturer, so the buyer may have had unrealistic expectations based on his experience with another rig. My TS-870S would match a wider range than my FT-1000MP Mark V. The Elecraft K2 and K3 tuners have a much wider range (10:1 SWR or more).

Jim AD4J


On Jan 25, 2011, at 11:44 PM, Jerry Flanders wrote:

> 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:
>> Content-Type: multipart/alternative;
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>> Content-Language: en-us
>> 
>> 
>> 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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