K1-4 - Can't find S-meter zero point

[iw7dmh]

Good morning,

I'm building a new K1-4 (sn. 3091) and I have completed the RF-Board part I.
My building experience il reported in my association forum
http://www.arilecce.it/index.php?option=com_kunena&func=view&catid=18&id=399&limit=6&limitstart=18&Itemid=94

It seems everything is working well as I have successfully completed receiver alignment procedure.
Now I'm going to find S-meter zero point following the steps described on page 53 of manual.
After disconnecting the antenna, the S-meter still indicate a full scale signal (all bars are on). This happen for any value of Lxx and I'm wondering if something in my test is wrong or this problem hides a mistake in my building procedure.
I also found a current consumption (on receiving) of about 35 mA that is a bit lower than the expected 55mA. Could it be another problem?
I hope you can help me.

Best regards.

73', IW7DMH
Enzo

[Don Wilhelm-4]

Enzo,

You most likely have a soldering problem or an incorrectly placed
component.  Component failures are rare unless they were damaged from
static when handling.
Take a look at the RF Board Schematic sheet 1.  To the right of and
below the "AGC" label on the left side you will see the components
associated with the AGC.  You can check the no signal voltages shown
there as an assist in finding the failure.  Make certain D2 is oriented
correctly, and that Q1 and Q2 are inserted in the correct holes.
It is also possible that Q1 was damaged by static when you inserted it -
the 2N7000 FETs are static sensitive.

73,
Don W3FPR

On 4/1/2012 5:05 AM, iw7dmh wrote:

> Good morning,
>
> I'm building a new K1-4 (sn. 3091) and I have completed the RF-Board part I.
> My building experience il reported in my association forum
> http://www.arilecce.it/index.php?option=com_kunena&func=view&catid=18&id=399&limit=6&limitstart=18&Itemid=94
> http://www.arilecce.it/index.php?option=com_kunena&func=view&catid=18&id=399&limit=6&limitstart=18&Itemid=94
>
> It seems everything is working well as I have successfully completed
> receiver alignment procedure.
> Now I'm going to find S-meter zero point following the steps described on
> page 53 of manual.
> After disconnecting the antenna, the S-meter still indicate a full scale
> signal (all bars are on). This happen for any value of Lxx and I'm wondering
> if something in my test is wrong or this problem hides a mistake in my
> building procedure.
> I also found a current consumption (on receiving) of about 35 mA that is a
> bit lower than the expected 55mA. Could it be another problem?
> I hope you can help me.
>
> Best regards.
>
> 73', IW7DMH
> Enzo
>
>

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[iw7dmh]

Dear Don,

thank a lot for your help! The problem now is solved!
As you suggested I checked RF signal on U1, U2, D2, Q2 and Q1, but for
the last component I found it was missing!
I checked it on assembly step on page 28 but I didn't install it at all.
So I have installed the 2N7000 FET and now S-meter is working very well
(using factory defaults).

Building K1 is an exciting training experience.
Thank you again.

73', Enzo
IW7DMH


Il 01/04/12 15.58, Don Wilhelm ha scritto:

> Enzo,
>
> You most likely have a soldering problem or an incorrectly placed
> component.  Component failures are rare unless they were damaged from
> static when handling.
> Take a look at the RF Board Schematic sheet 1.  To the right of and
> below the "AGC" label on the left side you will see the components
> associated with the AGC.  You can check the no signal voltages shown
> there as an assist in finding the failure.  Make certain D2 is
> oriented correctly, and that Q1 and Q2 are inserted in the correct holes.
> It is also possible that Q1 was damaged by static when you inserted it
> - the 2N7000 FETs are static sensitive.
>
> 73,
> Don W3FPR
>
> On 4/1/2012 5:05 AM, iw7dmh wrote:
>> Good morning,
>>
>> I'm building a new K1-4 (sn. 3091) and I have completed the RF-Board
>> part I.
>> My building experience il reported in my association forum
>> http://www.arilecce.it/index.php?option=com_kunena&func=view&catid=18&id=399&limit=6&limitstart=18&Itemid=94 
>>
>> http://www.arilecce.it/index.php?option=com_kunena&func=view&catid=18&id=399&limit=6&limitstart=18&Itemid=94 
>>
>>
>> It seems everything is working well as I have successfully completed
>> receiver alignment procedure.
>> Now I'm going to find S-meter zero point following the steps
>> described on
>> page 53 of manual.
>> After disconnecting the antenna, the S-meter still indicate a full scale
>> signal (all bars are on). This happen for any value of Lxx and I'm
>> wondering
>> if something in my test is wrong or this problem hides a mistake in my
>> building procedure.
>> I also found a current consumption (on receiving) of about 35 mA that
>> is a
>> bit lower than the expected 55mA. Could it be another problem?
>> I hope you can help me.
>>
>> Best regards.
>>
>> 73', IW7DMH
>> Enzo
>>
>>
>

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[iw7dmh]

As Don suggested I checked RF signal on U1, U2, D2, Q2 and Q1.
For the last component, surprisingly, I found it was missing!
I checked it on assembly step, on page 28, but I didn't install it at all.
So I have installed the 2N7000 FET and now S-meter is working very well (using factory defaults).

Thank you again Don!

73', Enzo
IW7DMH

[Mike Morrow-3]

> After disconnecting the antenna, the S-meter still indicate a full scale
> signal (all bars are on).

Can you tell if the receiver is detecting some sort of signal?  Verify
that S2, the OPER/OFS TEST switch, is in the OPER position.  In the
OFS TEST position it puts power on an intermediate transmitter stage
to allow you to adjust the transmit offset C13 properly in your receiver.
Your receiver will be picking that signal up unless you have returned S2
(below the RF circuit board) to the OPER position following the Offset
Adjustment on page 47.

If S2 was in OPER and you still have full S-meter indication:
1.  Report the DC voltage that you find on pin 2 of RF board U2,
    which is the AGC voltage being applied to that stage.
2.  Report the DC voltage found on RF board resistor pack pin 8 and 9
    which is also an earlier stage of the audio-derived AGC of the K1.
3.  Report the DC voltage found on pin 19 of the RF board front panel
    connector, which is the signal read by the front panel MPU to
    develop the S-meter indication.

> I also found a current consumption (on receiving) of about 35 mA
> that is a bit lower than the expected 55mA.

It should be even higher than 55 mA if you have the LCD backlight
option installed...probably over 60 mA, no signal.  So 35 mA sounds
low.  But...are you sure that your current meter is accurate at such
low ranges?

73,
Mike / KK5F
K1 SN 175
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[Mike Morrow-3]

I see the problem was solved during the two days that I wasn't getting
any Elecraft list postings, during which I replied not knowing your
problem was resolved:

> For the last component, surprisingly, I found it was missing!...
> So I have installed the 2N7000 FET...

After completing a kit, it is usually noteworthy if unused semiconductors
remain. :-)

Did you resolve the abnormal low current consumption issue?

Enjoy the K1.  Yours is almost 3000 units after mine.  After almost
12 years, it's still a gem.  All I could wish for now is an official
re-design of the KFL1-4's 40m/30m section for 12m/10m.  The other
section as now exists can already be set to cover any two of the
20m/17m/15m bands.  That would be perfect as the last new K1 product
from Elecraft, now at this time in the solar activity cycle.

73
Mike / KK5F
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[iw7dmh]

Dear Mike,

thank a lot for your answer.
In the mean time I solved the S-meter problem: it was a "newbie error". The K1 is my first important kit I'm trying to build ...
For current consumption it is probably as you said: my meter is not very accurate. The maximum scale I can set is 200 mA. Assuming an error of 10% (for so low current levels) the value of 35mA could be everything between 15 mA and 55 mA. 15mA is not likely to be a real value like, instead, could be 55 mA.

73', ENzo
IW7DMH

[iw7dmh]

> After almost
>12 years, it's still a gem.  All I could wish for now is an official
>re-design of the KFL1-4's 40m/30m section for 12m/10m.

Dear Mike,

I agree with you, but the release of the new KX3 could make anachronistic any wish to improve both the K1 and the KX1.
But, all in all, after 12 years from its first release, I'm here to build my K1 because I like very much its sound and at the end of my work I can say "I did it!".
In these days, of course, scenes are only for KX3 but I hope in a near future to see a light (only CW) version of KX3 fitted in a K1 case (I appreciate a lot the K1 form factor).
For the moment I enjoy my K1. Yesterday I ended receiver alignment and stayed all the night listening on 40m band . It was a pity having to unplug the filter board and the front panel to go on with the remaining building of RF board. :-)

73', Enzo
IW7DMH