[Premium-Rx] Racal RA6790GM CPU Version Number

[Odd-Jørgen Sagdahl]

Guy & list,

I have had my WJ HF-1000A for many years and for the last few years used it
with a Sherwood SE-3 synchronous detector. It has been my top receiver, and
I have tried many other high-end receivers that have not been able to match
it. Then - enter the RA6790/GM ...

But first a few word of what "DX" means for me.

a) I am only DX-ing mediumwave, so all my experience with these receivers
are based on frequencies below 1700 kHz - no exception ;-)

b) I only target overseas radio stations, primarily North America, Far East
and Pacific.

It useful to know that I am located in a "quiet" location - approx 63
degrees north, 10 degrees east, with good "protection" (mountains) to the
south. There are no local AM stations, and the strongest AM-signal on the
S-meter would be S9+50 dB. I often go on DX-peditions to even more quiet
locations. This means that receiver sensitivity is very important, maybe the
most important property of the receiver.

Last fall I got a RA6790/GM "in transit" and tested it for a while. It's not
the world's most user-friendly receiver, but I was impressed by the ability
of the receiver to pick up signals and make them legible. I would say that
it matched the HF1000A in most situations where there was little or no
interference from nearby channels. This unit was equipped with the standard
Racal filters. I used the receiver mostly with the SE-3.

I now have a RA6790/GM with (the hard-to-get) preamplifier + Rob Sherwood's
filters and it's dedicated SE-3. This unit was in excellent condition and
had been serviced by Gary Wingerd. This one works even better, and I find it
as an excellent second receiver. Second because it's not very fast to work
with when checking frequencies for carriers etc. like I often do when
looking for DX. It's still not as good as the HF-1000A on weak signals close
to European stations - this probably both due to the filters and the missing
notch.

To me the biggest disadvantage with the RS6790/GM is the missing notch. When
using the SE-3 I get 1/2/3/4 kHz tones (dependent on the filter width) when
I am too close to European stations. On the HF-1000A and a few other
receivers I have, there is an IF-notch that actually nulls the carrier of
the interfering stations. This is much more effective than the audio notch.
I do of course use an audio notch on the RA6790/GM now, but I believe this
could be better if I had an IF-notch (with have tried with and without on
the HF-1000A and there is significant difference).

So compared with the HF-1000A I will say it's the closest I have tried so
far. Regarding the RX-340 I have not worked a lot with it, but from what I
have seen I am not impressed by its performance. It's very user-friendly
(like the HF-1000A) but it does not fit my needs very well. I'd rather have
a (or two) RA6790/GM than the RX-340.

I have no experience with the WJ-8712P but as far as I know it's more or
less the same as the HF-1000A/WJ-8711 in half size. If you have other
experience with the WJ-8712P I would be interested to know.

73 de OJS
Trondheim, Norway




-----Original Message-----
From: premium-rx-bounces at ml.skirrow.org
[mailto:premium-rx-bounces at ml.skirrow.org]On Behalf Of Guy Atkins
Sent: 1. februar 2004 01:24
To: premium-rx at ml.skirrow.org
Subject: RE: [Premium-Rx] Racal RA6790GM CPU Version Number

...

Has anyone done any foreign mediumwave DXing with a RA6790GM? I'll be
interested to see how the RA6790GM stacks up against other DXer's receivers
like RX-340's, HF1000A's, WJ8712P's, etc. on the next Grayland (WA)
DXpedition.

73,

Guy