[Elecraft] strange tuning effect on k2

[Carel, pc5m]

Hi Bob and others who have replied to me (Thanks!)
 
Checked the choke RFC15= ok. I do have 5V on both sides of the choke.
 
One strange behaviour is that when I perform PLL lin. I set the K2 to 7.050
MHz . But when I perform the PLL lin. (by connecting to TP1 and measuring
the VFO freq) it goes to 12.094 MHz, which is 12.094-4.9136 = 7.1804 MHz. So
NOT the 7.050 MHz ! Is that normal behaviour ?
 
I can see that during the PLL lin. the VFO freq drops very smoothly from
12.094 to 12.085 (verified that with an external receiver on 12 MHz) and the
PLL lin. stops with an "end" message.
 
But stil when tuning, the 10Hz steps are not there !. Voltage on D16/D17 and
also the DAC U5 output  goes wild when turning slowly the freq. knob. On the
other hand the VFO voltage (at R30) is very smooth and well in normal range.
So it seems the DAC is programmed with rather erratic data....could it be I
have a defect EEPROM ? (it stores ok other things like S-meter Low/High
though...)
 
Thanks in advance,
 
Carel.

  _____  

From: G3VVT at aol.com [mailto:G3VVT at aol.com] 
Sent: Friday, June 10, 2005 1:04 AM
To: pc5m at xs4all.nl
Subject: Re: [Elecraft] strange tuning effect on k2


Hi Carel,
 
As a start check that the 100uH  choke RFC15 that feeds the 5V supply into
the PLL chip U4 pin 16 is not open circuit. Very easily damaged and gives
some odd effects when broken.
 
Regards,
Bob, G3VVT