[DSP-10] Another step of progress

[Don AE5K]

On 04/14/2013 11:48 AM, Don AE5K wrote:
> OK Mike, will do the coil peaking in transmit -- L8, L9, L10, L11, 
> L12, L13.  But this will probably not solve the intermittent problem 
> of the output level jumping around from -0.6 to +3.6 dBm and point in 
> between.  So it could be the output will increase with coil peaking 
> and that could be one problem we're seeing, but the other seems to be 
> in the tx chain around U5.

Started the DSP-10 up from cold, output read +2.0 dBm. (By the way, all 
this is at 144 Mhz. frequency, not the center of the 2 meter band, since 
ultimate use is 1296 transverter with frequencies 1296.0 to 1296.4 or so 
corresponding to 144.0-144.4 on the DSP10)

I do not have the proper tuning tool for the coils/inductors, finally 
used a metallic screwdriver, moving core a little at a time and 
observing power output.  About half the inductors made a little 
difference, the other half made quite a difference!  These are L8, L9, 
L10, L11, L12, L13.  With the clumsy tuning tool, I was able to get the 
output up to +8.0 dBm at 144 and +9.6 dBm at 146 MHz.  (This is read 
from the ANT connector, not TX out)

This still does not solve the erratic power out problem, but goes a long 
way to confirm the tx chain seems to all working.

I'll push on to try to find the cause of the erratic output, may solving 
this will increase the power even more (since usually have started with 
+3.6 instead of +2.0 dBm that I did with today).

Next step, try to pin down the erratic output to a single stage or 
between stages.

Thanks to much Mike and all the others who have offered suggestions.  
Still working on it.  Hey, I might have a good working DSP-10 soon 
without taking Bob up on his offer made a while ago to fix DSP-10's.

Don AE5K