Wednesday, 17 December 2014

PGA144 follow-up

My initial measurements now show
NF 0.6dB (usual caveats apply)
Gain 2.5 to 20.5dB ( adjustable)
Input third order intercept >+8dBm!
Input return loss ~9.5dB
Notch at 98MHz, -43dB wrt 145MHz at full gain
Unconditionally stable

All subject to further tests, of course.

Also
+8 to +16v working.
110mA current consumption
Can be optionally powered over the coax

Mechanically mounted in a screened tinplate box.
Connectors-  SMA female.

The PCB can be used without the box, if you want to mount the preamp inside another rig. Provision is made for two separate types of SMA connector on input and output to facilitate this. You could even use miniature coax cable direct to the input trace.

Enough............

Sam

PGA144

The new 144MHz preamplifier. The picture shows the prototype kit, built up for tests. A couple more are under construction.



Sam





Monday, 8 December 2014

Debugging transverters

I spent several hours today, fault finding on a couple of Anglian transverters assembled by customers.
A few dry joints were found on the reflow-soldered PCBs. 
A thorough visual inspectio, after assembling the board into the box, would probably have found the problems.
I was always taught and in turn, when a telecoms instructor, that visual inspection is he first thing you do when looking for faults. Power supplies are second!
In the case of Anglian transverters a visual inspection is also essential after the board is seam soldered into the case. It is quite easy to disturb parts if care is not taken during this part of the assembly.
Yes, both units are now working correctly!

Sam