K1 output

[Raimon-3]

For the atton. to Don Wilhelm W3FPR

Dear Don, I need again your help (I got your help time ago, for my K2
100, my problem was easily solved)

My K1 serial nr. 493, revision D, with Firmware upgrade Rev. 109, and
with KAT1, has been working flawlessly for some years.
Now, after some months QRT in my shack, I tried it again, and a problem
appeared:

No matter what is the Power Out setting (I can modify output setting),
when transmitting no bars are shown, in Tune mode shows P 0.1, and I
cannot change power output with WPM, Same behaviour connected to a dummy
load.

I removed KAT1, (I did not forget the jumper in J2), and the problem
persists.
Connected the K1 (without KAT1) to a dummy load through an Oak Hills QRP
wattmeter, it reads 2 watts no matter what is the power out setting. No
bars in the display.
When I transmit, the signal can be heard in a nearby receiver, at the
frequency shown in the display.
Reception is working OK.

So I proceeded to the Transmitter Signal Tracing

These are the readings (40 meter band)

PRE: 0.049 V
ATTN: 0.014 V
OSC: 0.08 V
MIX: 0.082 V
BUF: 1.581 V
TRI: 0.702 V
BPF: 0.422 V
TR2: 0.387 V
TR3: 0.000 V
DRV: 1.63V
PA: 16.15
ANT: 10.17 V
RFD: *0.02 V*

I suspect a bad solder developed over the years.
Where should I look for this failing behaviour?

Many thanks in advance for your help
Raimon Pardos
EA3EZO
[hidden email]


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[Don Wilhelm-4]

Raimon,

If you have 10 volts RF at the antenna jack and no DC voltage at the
cathode of D15, then you have either a bad D15 or a bad connection at
R36 or R37.  In fact, your earlier K1 you had lifted one end of the
resistor R36 when you installed the KAT1, and you must re-attach it when
you remove the KAT1.  It is on the bottom of the board.

If you do have DC voltage at D15, then R4 or R34 could have bad
soldering.  In a rare instance, you night find a shorted C43 - check the
resistance to ground from the cathode of D15, it should be close to 100k.

Once you have DC voltage from D15, I believe the power indication and
control will restore themselves to normal.

It is possible that you have a damaged diode in the KAT1 wattmeter -
especially suspect if an antenna was connected during the non-use period.

73,
Don W3FPR



On 5/20/2012 1:47 PM, raimon wrote:

> For the atton. to Don Wilhelm W3FPR
>
> Dear Don, I need again your help (I got your help time ago, for my K2
> 100, my problem was easily solved)
>
> My K1 serial nr. 493, revision D, with Firmware upgrade Rev. 109, and
> with KAT1, has been working flawlessly for some years.
> Now, after some months QRT in my shack, I tried it again, and a problem
> appeared:
>
> No matter what is the Power Out setting (I can modify output setting),
> when transmitting no bars are shown, in Tune mode shows P 0.1, and I
> cannot change power output with WPM, Same behaviour connected to a dummy
> load.
>
> I removed KAT1, (I did not forget the jumper in J2), and the problem
> persists.
> Connected the K1 (without KAT1) to a dummy load through an Oak Hills QRP
> wattmeter, it reads 2 watts no matter what is the power out setting. No
> bars in the display.
> When I transmit, the signal can be heard in a nearby receiver, at the
> frequency shown in the display.
> Reception is working OK.
>
> So I proceeded to the Transmitter Signal Tracing
>
> These are the readings (40 meter band)
>
> PRE: 0.049 V
> ATTN: 0.014 V
> OSC: 0.08 V
> MIX: 0.082 V
> BUF: 1.581 V
> TRI: 0.702 V
> BPF: 0.422 V
> TR2: 0.387 V
> TR3: 0.000 V
> DRV: 1.63V
> PA: 16.15
> ANT: 10.17 V
> RFD: *0.02 V*
>
> I suspect a bad solder developed over the years.
> Where should I look for this failing behaviour?
>
> Many thanks in advance for your help
> Raimon Pardos
> EA3EZO
> [hidden email]
>

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Help: http://mailman.qth.net/mmfaq.htm
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