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Telamon January 7th 06 07:06 AM

Passport to Worldband Radio
 
In article .com,
wrote:

Hello everyone, I buy the above book, quite useful it is too. There
are one or two things about it which I find hard to fathom. Why do
they go on so much about synchronous detector features on receivers?
I own a dozen or so receivers, some with and some without. The ones
without the SD are not that much more useful than a receiver with it.
For example, my ATS909/DX398 does not have it but my Sony SW7600GR
does. For me, the ATS is still, marginally a better receiver for my
needs. My Sony SW77 does not really seem to be much better when the
SD is on and on my AOR 7030, well the receiver is that good with a
good antenna that I never ever need it. With my Sat'800 it's also not
that useful although on occassions it has helped. My other bug bear
is that they plugged and plugged the Sat'800 when it first came out
and it was a pretty poor thing in my book. Much better now and I
would not sell mine but in the beginning they seemed blind to it's
quality control. Oh and one more thing, why oh why do they harp on
about receivers showing the time and frequency at the same time?
Useful, yes I know but not that important. I own a watch and a clock
and I am quite good at using them.


I don't mean to be funny but I don't understand why you are not able to
appreciate sync detection since you have radios with and without it. It
must have something to do with the part of the world in which you live
in or the signals you choose to listen too. Speaking for myself daytime
MW it usually has no benefit for example but dusk to dawn it makes a
huge difference where without it many stations would be unintelligible
for up to several minutes at a time. The example here are 50kW stations
50 to 200 miles from my location such as KFI and KOGO. These stations
have very strong ground wave daytime signals that at night are phased
with very strong sky-wave signals from the same stations. This vector
combination can be stable for minutes at a time, which if out of phase
means you can't understand a thing being said for minutes at a time
without the sync detector on.

For short wave sync detection helps about 50% of the time day or night.
Whether it helps or not depends on the signal path, ionospheric
conditions or both. Here the non sync distortion time is usually shorter
from 1/10 second to a few seconds most of the time.

I have sync detection on most of the time and only turn it off when I'm
band scanning.

Another benefit is on the RX340 and R8B I can select the side band for
sync detection. This is a very effective block for adjacent channel
interference. More effective than the passband tuning. The 7030+ can't
do that trick for you but the Sat 800 can.

--
Telamon
Ventura, California

HFguy January 10th 06 01:34 AM

Passport to Worldband Radio
 
wrote:
Hello again,
I can only assume it the place I live, London. I will accept that
sometimes the SD circuit does help a little but overall if i take PWBR
at face value in their view of it I think, for my situation they are
wrong. Perhaps where signal strenghts are weaker you are able to make
good use of it.
Regards,
Alan


Try listening to a SW station which is playing music with a lot of deep
fading. Notice how the audio (music) becomes distorted when the signal
fades, indicated by a large drop in the signal strength meter. Now turn
on the sync' detector. You'll see that the music still sounds clear
(undistorted) during the fading.


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