[PCR-1000] HF reception

[A10382]

There may be other non-amateur service users (like sw broadcast, utility
stations, etc. - maybe even some clandestine and/or 'spy number stations).
Very few of the 'Amateur Service' bands are exclusive to amateur radio.  In
fact, the amateur service is a 'secondary' user of some bands, meaning you
have to give way to the 'primary users'.

I had worked on comm systems at a few of our embassies years ago (pre-satcom
days) and it was not uncommon for many of the diplomatic communications
systems from other countries using whatever frequencies and modes that they
thought they could get away with.  The US, being of 'high adherence to laws
and standards', would of course never think of doing the same.

A recent "DC to almost Daylight" rf frequency allocation chart I've seen can
be found at:
http://www.ntia.doc.gov/osmhome/allochrt.html
Note that many places in the spectrum have multiple uses.
The chart is available in both a large PDF and text file.

It's a very large PD. file and not readable if you print it on a letter or
A$ sized paper.  However, I've been contemplating having it printed by
someone like 'AlphaGraphics' into a wall sized chart.

You might be getting a 'mixing' of the AM and SSB carriers or even multiple
SSB stations very close together.  - or - your front end may be a bit wide.
Try it on 'narrow' setting or play with the 'shift control'.  You might also
have a 'birdie' (a radio induced squeal) at that particular freq.  Most wide
band radios have a few scattered around.  I've even seen two identical rigs
have 'birdies' at different spots on the same band.. probably due to minor
component variances that cannot be tuned out.
---------

At the last ITU world radio conference in 2003, the union agreed to help
(read: probably give $$$) some broadcasters move off a part of the 40M band
(moving broadcast stations away from 7.1 to 7.2 I believe).  However, a lot
of countries do not subscribe to the ITU, are not treaty participants, fail
to regulate their broadcasters, or really just don't care.  That's why you
frequently find some sw AM broadcasters on frequencies not normally denoted
for such.

The actual band specs for Amateur are well defined and adhered to by ITU
member countries.  Some countries even restrict parts of the band that we
have here in the US (147-148 and 420-430MHZ not usable in some countries).
That's why many HTs (made in Japan) do not have the 420-430 capability which
seems to be primarily used for sstv in the US).  I raised a question on
another list about the actual 'specs' for the SW bands (e.g., 49M, 41M, 31M,
etc.).  I have a number of 'band charts' and many of them vary.  A good
example is the MW BC band that was expanded from 520-1620 KHZ to 520-1750
KHZ).  Despite that, quite a few AM radios today still cannot tune past
about 1650KHZ.

All of this seems to make radio in general more interesting.

73, Frank
_._ _.


----- Original Message -----
From: "David Carr" <dc@dcarr.org>
To: <pcr-1000@mailman.qth.net>
Sent: Thursday, January 22, 2004 2:31 PM
Subject: [PCR-1000] HF reception


> I just got my PCR1000 back from Icom for repair.  I was monitoring 20
> meters from downtown Houston today but noticed some strange effects.
> Using my 20m dipole I hear lots of strong tones (~500hz wide)  in the
> band and it just so happens that many of them seem to exist right on top
> of SSB stations.  This makes many stations uncopyable.  Some stations
> are unaffected but I can't help but wonder what is causing this effect.
> Is this the radio's doing (adjacent overload/something broken) or is
> there just a lot of QRM here that just happens to be centered on various
> stations?  The latter seems unlikely to me.
>



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