[PCR-1000] PCR1000 AC Adapter

[mikea]

On Tue, Jan 14, 2003 at 03:00:38PM -0500, A10382 wrote:
> Using a PCR1K usually means it's right next to the computer..

> Computers are notorious for RFI, EMI, etc...

> If you use TalkPCR, you can set the software to leave the radio on and
> selected to the last frequency you tuned when you exit TalkPCR.  You can
> then turn OFF the computer and the PCR1K will stay on and in receive mode...
> If the EMI goes away, then you know it was the computer itself.

> When home, I run my PCR1K from a Win'95 system.  There is a bit of hash,
> from the computer, particularly on lower frequencies (below about 50mHz).
> VHF and UHF are generally quiet - even when not in FM mode.

> When away, I run my PCR1K from a PalmPilot.  Using the Palm, the radio is
> very quiet (no EMI/RFI) on all frequencies.. even down to mid HF.

> I had taken the time to do some RFI shielding on the home system, and it did
> get slightly better,  however, most computer cases are not completely RF
> 'tight' - needing openings for peripherals, connectors, cords, etc.

Much, though probably not all, of the QRM will be from the
monitor and the video card -- especially if you're using a CRT
monitor instead of one of these fancy new flat-panel things.
The deflection yokes have to be driven pretty hard, and the
horizontal deflection ignal can be especially hard on things
because of all its harmonics. The dot clock signal out of the
video card generally is pretty well up in the high HF to low UHF
range (15 to 50 MHz, for a lot of monitors; this depends in a
_lot_ of things), and has a pretty short risetime, which makes
for biggie harmonics, too.

Ferrite beads can be _your_ friend, too, on just about every
cable.

-- 
Mike Andrews
mikea@mikea.ath.cx
Tired old sysadmin since 1964