[DSP-10] (no subject)

[Marius Hauki]

Hi DSP-10 list members.

I have progeammed the UHF3M21.HEX into a 27c512
eprom and inserted it (offset) into the eprom socket
of the EZ-kit since the 27c512 had fewer pins that the
memory chip that sat there originally.

When I run UHFA.EXE on the PC with the UHF3M21.HEX burnt in the eprom
I get an error msg  about the filter coefficients and that the filter design 
is not available. When I try to download UHF3.EXE with EZFAST instead, then 
the UHFA software starts to plot data and some data comes up on the spectrum 
analyser display. Then there is at least data transmission between the DSP 
and the PC going on it appears.

I get an error message from UHFA stating that there is a problem with PLL 
lock (E30 PLL UNLOCK). The PC beeps a few times per second as well.

I have hooked on the scope to a few points on the 19.68 MHz VCO signal chain 
and the output signal looks pretty messed up (distorted) after the U8 MMIC. 
Before U8 the signal looks quite clean! I am starting to think that I have 
killed the MMIC. It looks like the white dot is on the correct spot as well 
(white dot = input). The DC voltages look a little strange as well compared 
to what is described in the dsp-10 assembly manual. I measure 5.62 volts DC 
on pin 3 of U8. The voltage is 10V on L29 and R61 is marked with 331 so it 
looks like the resistor has the correct value as well.  I confirmed the 
measurements with the spectrum analyzer. The harmonics is as strong as the 
fundamentals coming out of U8.  The 10 MHz reference is present on both 
plls.

The VHF LO looks quite clean by the way, and the harmonics are down. When I 
look at the LD output from the U7 IC it has pulses on it. The LD output from 
U104 also has pulses on it.

Does pulses on the LD outputs indicate unlock ?

Is there anoyone on the list that has experienced similar problems and can 
give me a few hints ?

73 de LA9EEA
Marius



_________________________________________________________________
Join the world�s largest e-mail service with MSN Hotmail. 
http://www.hotmail.com