AOR 7030+ vs R8B passband?
 

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.

It's not a question of being any good (the R8B is good) but whether the
7030 is any better. Some slight edge.

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

hi Ron:

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?

yes, not via "suppression" [filter] but by its first mixer [SD5400] being
able to handle the energy.

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.

the AGC can be turned off, what cannot be fixed is close-in dynamic range.

It's not a question of being any good (the R8B is good) but whether the
7030 is any better. Some slight edge.

yes. 7030 2-kHz DR is 82-dB; R8B 5-kHz DR is 75-dB. 5-kHz IP3 is +1 dBm
[7030] versus -20 dBm [R8B].

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.

at that spacing it would be difficult but you might try a series-resonant
trap.

regards,
phil :)

Ron Hardin schrieb:

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?

It should be, particularly when using the 2.something kHz (SSB) filter.
The 4 kHz filter with some offset via the PBS should also work quite
nicely, though. (IIRC it's a rather good Murata CFK filter, the wider
ones are rather ordinary CFWs. They do, however, benefit from
cascading.)

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.

So the synch selects one sideband but the AGC reacts because the signal
is still within the filter passband... kinda the problem a 7600G has in
SSB when a stronger station is talking on the other sideband.

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.

The Radio Netherlands review states a rejection of 99 dB @ 10 kHz
distance for the 2.1 kHz filter, unfortunately there are no measurements
for the 4 kHz in the "Plus" but the 5.4 kHz filter (which in itself is
not too exciting) already obtained 65 dB. (Due to its cascaded filters
and low-noise oscillator, the AR7030 excels in terms of filters, no
doubt. The Drake uses coil filters at a 50 kHz IF, which are certainly
quite good but probably can't keep up with that kind of performance.)
Should things get really hairy, you can still manually adjust the AGC.

Stephan (whose AR7030+ still needs a Decent Antenna[tm])
--
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In article ,
Ron Hardin wrote:

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.

It's not a question of being any good (the R8B is good) but whether the
7030 is any better. Some slight edge.

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.

I own both radios and generally the R8B blocks better with a combination
of pass band filter, pass band offset and sync set to the appropriate
side band. The manual AGC controls probably will not help much here
other than turning it off and setting a level manually. If that does not
do it you will have to do some antenna work or use a blocking filter of
some type to knock down the stronger station. The differentiator between
the radios is the R8B has selectable sync.

--
Telamon
Ventura, California

Every solid state Drake receiver that I have had, except the R7/TR7 seems to
have that problem. I am not sure if it is because some of the AGC control
voltage is being derived ahead of the final I.F. system. I don't notice this
problem with the 7030. I don't think I would replace the R8 with the
7030....the R8 is a good receiver.

Pete

"phil :)" wrote in message
...
hi Ron:

Is the 7030 any better than the R8B in suppressing a loud MW station
10 kHz away, when listening to the distant sideband of the wanted
station?

yes, not via "suppression" [filter] but by its first mixer [SD5400] being
able to handle the energy.

The R8B gets its agc hit by the unwanted station (which is really really
strong) in this situation and so makes the wanted station unlistenable.

the AGC can be turned off, what cannot be fixed is close-in dynamic range.

It's not a question of being any good (the R8B is good) but whether the
7030 is any better. Some slight edge.

yes. 7030 2-kHz DR is 82-dB; R8B 5-kHz DR is 75-dB. 5-kHz IP3 is +1 dBm
[7030] versus -20 dBm [R8B].

I can't null the unwanted station because it lines up with the desired
station exactly. A little better tails on the passband might fix it.
We're talking about ripples I think, and how far down they really are.

at that spacing it would be difficult but you might try a series-resonant
trap.

regards,
phil :)