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T-1 problem fixed!

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Irma & Linas(LY2H)

T-1 problem fixed!

Hello group,

This might be usefull to all who own the Elecraft T-1 antenna tuner. Some
time ago I complained to this group and to the Elecraft support on problems
with T-1 had stopped tuning. The answer from the Elecraft Support was
quick and extremely usefull! Please find it below! Following their advise
I did check the resistance on diodes D1 and D2. It proved something was
wrong with the chain of the D1. The diode D1 though turned to be ok . The
faulty part was... the capacitor C11 wich was dead shorting the resistor R3
to ground. I replaced the capacitor C11 with a new one ( not SMD by the
way, the " normal" one) and bingo! The problems gone , T-1 runs smoothly
and quickly .
Hope this info is usefull for the T-1 owners and you do have the schematic
diagram of the unit in order to better understand the whole thing.

73 de Linas LY2H

<<<Elecraft Support:

For the tuner to operate, it must see about a 0.5 to 3VDC FWD SWR sensor
level (depending on the power level) from diode D1's cathode, and a smaller
REFL sensor DC level (higher with more SWR) from D2's cathode - both when
you transmit with 1-10w or so of RF from your transmitter. If the 1N5711
diodes are damaged, that won’t happen.

If the diodes are OK, there should be about 123K ohms (R3 + R5 or R4 + R6)
between each diode cathode and ground when tested with an ohmmeter, with
the positive lead on the banded end (cathode) and the negative lead to
ground. Bad diodes will have too much reverse leakage in the reverse
direction through the diodes and back through R1 or R2 to ground.

Then, if your meter has a diode test function, there should be about 0.38
to 0.40VDC of diode drop across the 1N5711 diodes, with the + lead to
anode, - lead to the cathode. 1N34A diodes will work in a pinch, but they
are not as good as the 1N5711 diodes which should be installed if you need
to get them.>>>
---------

<<<On Sunday, February 26, 2017 at 1:09:28 PM UTC-7, Linas Balsys wrote:

Hello Support,

>
> My Elecrat T-1 mini-autotuner stopped working after some 10 years of
> flawless service...
> It started behaving erratically , it either does not react to the RF input
> , or if it does then never finds the tune ending up with the red LED on.
> It is not related with the antenna type, it is all the same even with the
> perfectly tuned R-8 on or a dummy load. Cables are ok. The self LC test
> procedure as described in the manual , though went ok. Disconnecting and
> re-connecting and replacing the battery doesn' help. I also tried to eject
> and reinstal the microprocessor chip to no avail. Visual inspection of the
> boards brought nothing suspicious and resoldering the BNC contacts hasn't
> made any difference. >>>
>
> Thanks for your advice!
>
> 73 de Linas Balsys, LY2H >>>>
>
>
> Sent from my iPad

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Nr4c

Re: T-1 problem fixed!

Thanks for letting us know you are up again. And, thanks for the solution.

Chances are someone else will learn from your experience.

Enjoy.

Sent from my iPhone
...nr4c. bill

> On Mar 4, 2017, at 2:54 PM, Irma Linas <[hidden email]> wrote:
>
> Hello group,
>
> This might be usefull to all who own the Elecraft T-1 antenna tuner. Some
> time ago I complained to this group and to the Elecraft support on problems
> with T-1 had stopped tuning. The answer from the Elecraft Support was
> quick and extremely usefull! Please find it below! Following their advise
> I did check the resistance on diodes D1 and D2. It proved something was
> wrong with the chain of the D1. The diode D1 though turned to be ok . The
> faulty part was... the capacitor C11 wich was dead shorting the resistor R3
> to ground. I replaced the capacitor C11 with a new one ( not SMD by the
> way, the " normal" one) and bingo! The problems gone , T-1 runs smoothly
> and quickly .
> Hope this info is usefull for the T-1 owners and you do have the schematic
> diagram of the unit in order to better understand the whole thing.
>
> 73 de Linas LY2H
>
> <<<Elecraft Support:
>
> For the tuner to operate, it must see about a 0.5 to 3VDC FWD SWR sensor
> level (depending on the power level) from diode D1's cathode, and a smaller
> REFL sensor DC level (higher with more SWR) from D2's cathode - both when
> you transmit with 1-10w or so of RF from your transmitter. If the 1N5711
> diodes are damaged, that won’t happen.
>
>
> If the diodes are OK, there should be about 123K ohms (R3 + R5 or R4 + R6)
> between each diode cathode and ground when tested with an ohmmeter, with
> the positive lead on the banded end (cathode) and the negative lead to
> ground. Bad diodes will have too much reverse leakage in the reverse
> direction through the diodes and back through R1 or R2 to ground.
>
> Then, if your meter has a diode test function, there should be about 0.38
> to 0.40VDC of diode drop across the 1N5711 diodes, with the + lead to
> anode, - lead to the cathode. 1N34A diodes will work in a pinch, but they
> are not as good as the 1N5711 diodes which should be installed if you need
> to get them.>>>
> ---------
>
> <<<On Sunday, February 26, 2017 at 1:09:28 PM UTC-7, Linas Balsys wrote:
>
> Hello Support,
>>
>> My Elecrat T-1 mini-autotuner stopped working after some 10 years of
>> flawless service...
>> It started behaving erratically , it either does not react to the RF input
>> , or if it does then never finds the tune ending up with the red LED on.
>> It is not related with the antenna type, it is all t