[hpsdr] Penelope does not transmit... help!

[Helmut Oeller]

Hi Michael,

the OPA2674 is very sensitive to overvoltage. Don't extend the operation voltage of 12V.  See data sheet.

73, Helmut, DC6NY


-----Ursprüngliche Nachricht-----
Von: Hpsdr <hpsdr-bounces at lists.openhpsdr.org> Im Auftrag von Michael Carey
Gesendet: Samstag, 15. Februar 2020 02:47
An: hpsdr at lists.openhpsdr.org
Betreff: Re: [hpsdr] Penelope does not transmit... help!

***** High Performance Software Defined Radio Discussion List *****

Hello Marc,

Thank you for you comprehensive reply.

After looking at my Penelope, I think I know what has failed!  The
OPA2674 has a physical burn mark on it!
I'm not sure when or how it failed.  My HPSDR rig is either connected to a dummy load or is connected to a tuned antenna. I've ordered some replacements from Mouser, and I'll swap it out and see what happens.

While I wait for the replacements to arrive, I will go through your check list and see if everything else is OK.

73

Michael Carey
VK5ZEA

On 14/02/2020 10:23 pm, Marc OLANIE wrote:
> Hi Michael
>
> I never touch or had a look at any Penelope board, but the schematic is "genetically" close to every other hpsdr rigs.
> I think it could be interesting to have a look with a scope and volmeter at :
> - opa2674 inputs (output and input of the input transformer TC4-1T, rf 
> signal when TX)
> - check the presence of the signal at JP3 -input of the tx lowpass 
> filter , rf signal when TX
> - check the balanced signal on the output of the AD9744 DAC (pin 21 
> and 22) , rf signal when TX
> - test the level on the output of Q1 (tx switching, 2N7002), level 
> change when tx
> - check the presence of the several clk traces (125 MHz, 10 MHz at U5 
> and U2 or U3)
> - test the several power rails : 1.2 V on the output of U15, hot side 
> of C52, 3.3V on the output of U4/C7, the main 12V bus (5 test points, 
> the most important beeing the one located on L1, close to the opa2674) 
> and the 5V rail
>
> Hope it will help
> VY 73
> Marc f6itu
>
>
>
> -----Message d'origine-----
> De : Hpsdr <hpsdr-bounces at lists.openhpsdr.org> De la part de Michael 
> Carey Envoyé : vendredi 14 février 2020 03:47 À : 
> hpsdr at lists.openhpsdr.org Objet : [hpsdr] Penelope does not 
> transmit... help!
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Everybody,
>
> I've just noticed today that my Penelope board doesn't transmit any more!
>
> I used to get a nice solid 500 mW from the BNC socket and now I get 
> virtually nothing.   My OZ2CPU Wattmeter is showing around 630 nW when 
> I hit tune with drive at 100%.  This is the same across all bands 
> 160m-10m
>
> I'm guessing the fix might be a little tricky.  Can anyone point to where on the PCB I should start looking!
>
> 73
>
> Michael
> VK5ZEA
>
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