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Fw: KAT100 null

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NZ0T

Fw: KAT100 null

I just checked my analyzer with a good known 50 Ohm load and it read 60 ohms
so I'm sure my dummy load is fine - the analyzer reads 10 ohms high I guess.
I have checked all connections/solder joints and yes the input wire goes
through T1 lol. I do get a null but at around 2 volts, not near zero as it
should be. When I attempt power calibration at 20 watts I can't get near
the 2.7 volts specified -I can only get to around 2 volts with full
clockwise on R4. Since that is the same as the null could U5 be bad? Just
occurred to me.
Ackkkkkk!

----- Original Message -----
From: "Bill Carpenter" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, December 08, 2007 1:54 PM
Subject: Re: [Elecraft] KAT100 null

> Hi Don,
> I'm using my old Heath dry dummy load/wattmeter which shows 60 ohms pure
> resistive on my MFJ analyzer (who knows how accurate that is) and I'm
> using a good, very short jumper. All connections look fine and yes, the
> input jack wire goes through T1 lol. I do get a null but it's at around
> 1.9 to 2 volts on my DMM.
> This is driving me crazy - it has to be something simple I'm missing!
> ----- Original Message -----
> From: "Don Wilhelm" <[hidden email]>
> To: "Bill Carpenter" <[hidden email]>
> Cc: "elecraft list" <[hidden email]>
> Sent: Saturday, December 08, 2007 1:04 PM
> Subject: Re: [Elecraft] KAT100 null
>
>
>> Bill,
>>
>> That indicates something is wrong. Are you using a good dummy load with
>> a very short connecting cable? If you have any doubts about the dummy
>> load, check it (and the cable too) with an antenna analyzer - anything
>> other than a 50 ohm resistive load can cause problems with obtaining a
>> good null.
>>
>> The other thing that can cause difficulty with the null is any reactance
>> in the tuner - there is a small amount of residual, but not enough to
>> change the null drastically. Look the tuner over carefully for
>> unsoldered connections in the relays and inductor and capacitor parts of
>> the tuner.
>>
>> As for 'dumb' things, make certain the wire to the input jack goes
>> through the center of the toroid.
>>
>> 73,
>> Don W3FPR
>>
>> Bill Carpenter wrote:
>>> Everything has gone fine with my new KAT100 until I got to the SWR
>>> bridge null adjustment. The best null I can get is about 1.9 to 2.0
>>> volts. I checked T1 and even took it out and rewound it with new wire.
>>> The 4 leads of T1 are in the correct holes and continuity checks fine.
>>> Everything else in the bridge circuit looks fine to me and the coax
>>> jumpers I'm using are fine. I have the KPA100 so I'm attempting the
>>> adjustment at 20 watts. U5 is installed correctly.
>>>
>>> Very frustrating! Any help is GREATLY appreciated!!
>>>
>>> 73,
>>>
>>> Bill NZ0T
>>>
>>
>

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NZ0T

Re: KAT100 null

Well, as almost always happens this was self-inflicted. I have extra
toriods and wire left over from my previous Elecraft kits so I wound a new
T1, put it in and guess what?
It works! Very well I might add.

Thanks to all who offered help!
----- Original Message -----
From: "Bill Carpenter" <[hidden email]>
To: "elecraft list" <[hidden email]>
Sent: Saturday, December 08, 2007 4:17 PM
Subject: Fw: [Elecraft] KAT100 null

>I just checked my analyzer with a good known 50 Ohm load and it read 60
>ohms so I'm sure my dummy load is fine - the analyzer reads 10 ohms high I
>guess. I have checked all connections/solder joints and yes the input wire
>goes through T1 lol. I do get a null but at around 2 volts, not near zero
>as it should be. When I attempt power calibration at 20 watts I can't get
>near the 2.7 volts specified -I can only get to around 2 volts with full
>clockwise on R4. Since that is the same as the null could U5 be bad? Just
>occurred to me.
> Ackkkkkk!
>
> ----- Original Message -----
> From: "Bill Carpenter" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, December 08, 2007 1:54 PM
> Subject: Re: [Elecraft] KAT100 null
>
>
>> Hi Don,
>> I'm using my old Heath dry dummy load/wattmeter which shows 60 ohms pure
>> resistive on my MFJ analyzer (who knows how accurate that is) and I'm
>> using a good, very short jumper. All connections look fine and yes, the
>> input jack wire goes through T1 lol. I do get a null but it's at around
>> 1.9 to 2 volts on my DMM.
>> This is driving me crazy - it has to be something simple I'm missing!
>> ----- Original Message -----
>> From: "Don Wilhelm" <[hidden email]>
>> To: "Bill Carpenter" <[hidden email]>
>> Cc: "elecraft list" <[hidden email]>
>> Sent: Saturday, December 08, 2007 1:04 PM
>> Subject: Re: [Elecraft] KAT100 null
>>
>>
>>> Bill,
>>>
>>> That indicates something is wrong. Are you using a good dummy load with
>>> a very short connecting cable? If you have any doubts about the dummy
>>> load, check it (and the cable too) with an antenna analyzer - anything
>>> other than a 50 ohm resistive load can cause problems with obtaining a
>>> good null.
>>>
>>> The other thing that can cause difficulty with the null is any reactance
>>> in the tuner - there is a small amount of residual, but not enough to
>>> change the null drastically. Look the tuner over carefully for
>>> unsoldered connections in the relays and inductor and capacitor parts of
>>> the tuner.
>>>
>>> As for 'dumb' things, make certain the wire to the input jack goes
>>> through the center of the toroid.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>> Bill Carpenter wrote:
>>>> Everything has gone fine with my new KAT100 until I got to the SWR
>>>> bridge null adjustment. The best null I can get is about 1.9 to 2.0
>>>> volts. I checked T1 and even took it out and rewound it with new wire.
>>>> The 4 leads of T1 are in the correct holes and continuity checks fine.
>>>> Everything else in the bridge circuit looks fine to me and the coax
>>>> jumpers I'm using are fine. I have the KPA100 so I'm attempting the
>>>> adjustment at 20 watts. U5 is installed correctly.
>>>>
>>>> Very frustrating! Any help is GREATLY appreciated!!
>>>>
>>>> 73,
>>>>
>>>> Bill NZ0T
>>>>
>>>
>>
>
>
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