[hpsdr] HPSDR EMI Issues

[Luke Steele]

At 05:17 PM 10/09/2011 -0700, FRANCIS CARCIA wrote: 
>
> ***** High Performance Software Defined Radio Discussion List ***** 
>
> Hi everyone,
> From a humble emi guy
> I read there  are a number of issues with signals leaking out of modules and
> strong RF getting in.



>From an operation point of view, having all the connectors on the boards
protruding from the case is inconvenient.
In my application, using the Pandora enclosure, which is quite a nice box to
put HPSDR into, along with a 100W PA block, and room for a few more bits and
pieces, such as a planned 6m IPA and some T/R and other switching circuits, is
just fine.
With the HPSDR board layout, having the RF connectors sticking out of the
enclosure is not convenient, as those need to be patched straight back into
the
interior. I'm using the holes punched for Alex for that. Same with the control
connector on Penelope. The microphone connector is routed back into the
enclosure, to an 8-pin jack on the blank panel, which in my application is the
"front" panel. I even have the headphone jack routed straight back into the
enclosure to a headphone jack on the front panel, and an internal audio amp
and
speaker. I didn't like having the antenna of amplified computer speakers
feeding RF back into Mercury. All the above would be better on the other
end of
the boards. The threaded pillars are set up for Atlas to orient the boards
with
the connectors protruding.
The only connections out of the enclosure directly from the HPSDR boards is
the
9-pin connector on Magister for the paddle, and USB to the computer.
Obviously, to redesign to my whim would be impractical, so I'll just make do
with my own solutions above.
I have planned a small Al plate to go behind the holes punched for Alex, and
mount several standard BNC bulkhead mount connectors to protrude through the
punched holes. Presently I have a couple of insulated BNCs mounted in the
holes. The insulated BNCs have a larger flange, and mount directly in the Alex
holes. I also have an insulated RCA connector mounted there for the external
T/R switching for an amplifier.
The only time I've had issues with RF (I will run several hundred watts at
times) was when I had the external speakers. Now I nearly always use
headphones.
I tried to find a spurious on 144.390 MHz, using an FM rig with a proper
antenna outside, and found nothing notable.
I have several transceivers here in my station, but these are gathering dust,
as I work all my DX using the HPSDR.
That's enough of my rambling for now.
Vy 73,
Luke VK3HJ 
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