K2 - no TX power problem

[GS-3]

Hi,

I have a problem: No TX Out on my freshly assembled K2.

f = 7100
Vpwr = 5V
Valc = 7,5V
Power reading on LCD = 0.2W (desired 5W)
Power consumption 440mA on 12,4V

At TP2 on transmit I get a nice signal on my oscilloscope, abt 0.005 Vrms

But behind TP2 the signal vanishes. All measurements are way too low, if present at all. At U10 Pin 4 there's only a short Jump to 5V and immediately back to 0 on keying. No HF detectable.

I unsoldered the Diode D36 and checked for resistance. Infinite in both directions. Does this mean what I think? This D is broken?

Do you need any more information?
What else could I check?

Thanks for any advice in advance!


Gerhard Schwanz
DH3FAW
mailto:[hidden email]
http://www.gs-personal.de


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[Don Wilhelm-2]

Gerhardt,

Yes, I too would believe D36 is broken - it is quite fragile and will crack
if the leads are bent too close to the glass body - HANDLE WITH CARE.

You can temporarily substitute a 1N4007 diode until you can obtain a
replacement (the 1N4007 was used in the D36 location until the keying
waveshape change was implemented).  You can likely find a 1N4007 easier than
the proper PIN diode.

With the 1N4007 in D36, your keying waveshape may not be exactly correct (it
will be close enough), and it should get you through the testing of your K2.


73,
Don W3FPR

Life is what happens when you are making other plans

----- Original Message -----

At TP2 on transmit I get a nice signal on my oscilloscope, abt 0.005 Vrms

But behind TP2 the signal vanishes. All measurements are way too low, if
present at all. At U10 Pin 4 there's only a short Jump to 5V and immediately
back to 0 on keying. No HF detectable.

I unsoldered the Diode D36 and checked for resistance. Infinite in both
directions. Does this mean what I think? This D is broken?



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[JEAN-FRANCOIS MENARD-2]

It seems that I have a TX problem too. Just to prevent removing D36 for
nothing because it's fragile, could someone give a result that I should
read on my DMM when D36 is working properly ???

Le 04-06-24, à 13:59, Don Wilhelm a écrit :

> Gerhardt,
>
> Yes, I too would believe D36 is broken - it is quite fragile and will
> crack
> if the leads are bent too close to the glass body - HANDLE WITH CARE.
>
> You can temporarily substitute a 1N4007 diode until you can obtain a
> replacement (the 1N4007 was used in the D36 location until the keying
> waveshape change was implemented).  You can likely find a 1N4007
> easier than
> the proper PIN diode.
>
> With the 1N4007 in D36, your keying waveshape may not be exactly
> correct (it
> will be close enough), and it should get you through the testing of
> your K2.
>
>
> 73,
> Don W3FPR
>
> Life is what happens when you are making other plans
>
> ----- Original Message -----
>
> At TP2 on transmit I get a nice signal on my oscilloscope, abt 0.005
> Vrms
>
> But behind TP2 the signal vanishes. All measurements are way too low,
> if
> present at all. At U10 Pin 4 there's only a short Jump to 5V and
> immediately
> back to 0 on keying. No HF detectable.
>
> I unsoldered the Diode D36 and checked for resistance. Infinite in both
> directions. Does this mean what I think? This D is broken?
>
>
>
> _______________________________________________
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> Post to: [hidden email]
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===============================================
Jean-François Ménard / VA2VYZ
[hidden email]

Club d'Astronomie Amateur de Sherbrooke
Club Radio Amateur de l'Estrie

Mon site web personnel : http://homepage.mac.com/jfmenard
===============================================

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[GS-3]

Hi,

thanks for recommending another Diode. The vendor
suggested to use UF4007 instead of 1N4007 maybe. What
do you think?

Of course it's hard to get the D36 here in Germany.
Any idea, German readers???

I think of getting it at

- HAM Radio,
- QRP-Projekt
- or Elecraft

73

Gerhard




--- Don Wilhelm <[hidden email]> schrieb: > Gerhardt,

>
> Yes, I too would believe D36 is broken - it is quite
> fragile and will crack
> if the leads are bent too close to the glass body -
> HANDLE WITH CARE.
>
> You can temporarily substitute a 1N4007 diode until
> you can obtain a
> replacement (the 1N4007 was used in the D36 location
> until the keying
> waveshape change was implemented).  You can likely
> find a 1N4007 easier than
> the proper PIN diode.
>
> With the 1N4007 in D36, your keying waveshape may
> not be exactly correct (it
> will be close enough), and it should get you through
> the testing of your K2.
>
>
> 73,
> Don W3FPR
>
> Life is what happens when you are making other plans
>
>  

       

       
               
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[G3VVT]

Hi Gerhard,
 
The IN4007 is available worldwide, so should be available in Germany. In  the
UK they are widely retailed at 6 to 15 cents in Euros.
 
Not come across the UF4007 before though possibly a Seimens or similar  
branding of the same item?
 
The correct item for D36 I believe is HP PIN diode 5082-3081. These  are more
difficult to source in the UK, though I have bought HP diodes in the  past
from Mainline Electronics at Leicester. They list another surface mounted  PIN
diode type HSMP-3810 as being similar.
 
The item I received with my K2 kit in May appeared to be marked  338 3081.
 
Possibly better to cut your losses and order a replacement direct from  
Elecraft which could normally be delivered to you within 7 days by airmail. An  
e-mail to Scott at Elecraft should give you the prompt answer on cost.
 
Regards,
Bob, G3VVT
K2 #4168
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[Martin-85]

Hello Gerhard,
did a GOOGLE-Search for 5082-3081   .

Result: www.segor.de

Segor Electronics in Berlin

http://cgi.segor.de/user-cgi-bin/sidestep2.pl?foto=1&Q=5082-3081&M=1

leads you directly to the product.

--
Best regards,
 Martin

K2 #2706                            mailto:[hidden email]


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