Lostgallifreyan wrote:
Jeff wrote in :

It seems very strange that you are taking things to the ultimate when
considering coax cable, whilst considering using a very inferior
portable radio for your reception!!


Not really. A few tens of metres of cable whose cost is not more than 3 times
the cheapest of satellite coaxes, and whose total cost is less than half the
lowest cost of that radio when found second-hand, is hardly overdoing it.

I think the point is that radio is very much under-doing it!!!

Jeff

Jeff wrote in
:

Lostgallifreyan wrote:
Jeff wrote in
:

It seems very strange that you are taking things to the ultimate when
considering coax cable, whilst considering using a very inferior
portable radio for your reception!!


Not really. A few tens of metres of cable whose cost is not more than 3
times the cheapest of satellite coaxes, and whose total cost is less
than half the lowest cost of that radio when found second-hand, is
hardly overdoing it.

I think the point is that radio is very much under-doing it!!!


Why are you so set against that radio? A lot of people like it (some of them
enough to modify it rather than replace it). What do you recommend? And how
much would it cost? This thread wasn't about that radio but this is worth
pursuing, you seem to have a strong feeling about it. I just bought it
because it seemed like a good cheap base to start from. (Not cheap if I'd had
to buy new, but I purposely avoided that).

Lostgallifreyan wrote in
:

Jeff wrote in
:

Lostgallifreyan wrote:
Jeff wrote in
:

It seems very strange that you are taking things to the ultimate when
considering coax cable, whilst considering using a very inferior
portable radio for your reception!!


Not really. A few tens of metres of cable whose cost is not more than
3 times the cheapest of satellite coaxes, and whose total cost is less
than half the lowest cost of that radio when found second-hand, is
hardly overdoing it.

I think the point is that radio is very much under-doing it!!!


Why are you so set against that radio? A lot of people like it (some of
them enough to modify it rather than replace it). What do you recommend?
And how much would it cost? This thread wasn't about that radio but this
is worth pursuing, you seem to have a strong feeling about it. I just
bought it because it seemed like a good cheap base to start from. (Not
cheap if I'd had to buy new, but I purposely avoided that).


Further, the ATS-909 is a fairly old design. Not many appear used on eBay,
and new ones still sell for what I think are excessive prices, from Germany,
Japan and elsewhere. Bad radios surely get sold on as fast as people can
pass them off on someone else. They're unlikely to be in shorter supply
secondhand than new, when they're as old a design as this one is, and very
few second-hand ones remain unsold when an auction ends. I'm not trying to
correlate buyers opinions with the finer points of radio engineering, but it
remains a fact that people would rather keep them and use them than sell them
on, which is fairly convincing as an argument to get one if the price is
good, so I got one. Had to wait a few months too, for an auction that had low
competition, but I think it was worth it. A lot of people documented
modifications, suggesting an enthusiastic technically adept following. That
is one of the things that helped me decide to get one. It means I'm not
reliant on one supplier for info or advice if I need to fix or modify it.

Really poor radios don't go through what I just decribed, they sink without
trace instead of surviving for over a decade with such deep involvement from
so many of their users.

Lostgallifreyan wrote:
Lostgallifreyan wrote in
:

Jeff wrote in
:

Lostgallifreyan wrote:
Jeff wrote in
:

It seems very strange that you are taking things to the ultimate when
considering coax cable, whilst considering using a very inferior
portable radio for your reception!!

Not really. A few tens of metres of cable whose cost is not more than
3 times the cheapest of satellite coaxes, and whose total cost is less
than half the lowest cost of that radio when found second-hand, is
hardly overdoing it.
I think the point is that radio is very much under-doing it!!!

Why are you so set against that radio? A lot of people like it (some of
them enough to modify it rather than replace it). What do you recommend?
And how much would it cost? This thread wasn't about that radio but this
is worth pursuing, you seem to have a strong feeling about it. I just
bought it because it seemed like a good cheap base to start from. (Not
cheap if I'd had to buy new, but I purposely avoided that).


Further, the ATS-909 is a fairly old design. Not many appear used on eBay,
and new ones still sell for what I think are excessive prices, from Germany,
Japan and elsewhere. Bad radios surely get sold on as fast as people can
pass them off on someone else. They're unlikely to be in shorter supply
secondhand than new, when they're as old a design as this one is, and very
few second-hand ones remain unsold when an auction ends. I'm not trying to
correlate buyers opinions with the finer points of radio engineering, but it
remains a fact that people would rather keep them and use them than sell them
on,

OR throw them away when they die, or put them is a box in a closet. You
really don't know.


which is fairly convincing as an argument to get one if the price is
good, so I got one. Had to wait a few months too, for an auction that had low
competition, but I think it was worth it. A lot of people documented
modifications, suggesting an enthusiastic technically adept following.

That technically adept following could not provide any useful
information on the input impedance. While actually knowing the impedance
may not be of much value in your endeavors, given the availability of
the schematic, someone could have modeled the input in Spice.


That
is one of the things that helped me decide to get one. It means I'm not
reliant on one supplier for info or advice if I need to fix or modify it.

Really poor radios don't go through what I just described, they sink without
trace instead of surviving for over a decade with such deep involvement from
so many of their users.

A really good radio probably doesn't need a bunch of modifications to
deal with deficiencies.

Some radios hang around because they were built in large volumes.
Quality and performance may mean little.

The point that was made is your radio does not really warrant the effort
your are putting into the antenna. Any variety of quick and easy
antennas may give you adequate results.

So, here is what I see.
1) Worrying about the radio's input impedance is of little value
2) The choice of coax won't make much difference - performance wise, but
copper braid is much easier to solder to.
3) A simple wire antenna at the end of the coax should be sufficient
4) A balun (or un-un for the picky) between the antenna and coax is
probably worthwhile. 9:1 or 10:1 won't make any difference.
5) Figure out what you are going to do about lightning protection.
6) Rather than spend weeks sorting out the details, string up some wire
and listen to the radio.

joe wrote in :

The point that was made is your radio does not really warrant the effort
your are putting into the antenna. Any variety of quick and easy
antennas may give you adequate results.


On the other hand, I've been told that a good RF ground and a well-sited
antenna make more difference than anything else. Who cares about the radio, I
can change that. If I don't at least try to get the antenna right, what would
be the point of that change in radio? Where I live I'm unlikely to ever get
much, but spending what amounts to a couple of weeks food money on trying is
worth a go.

So, here is what I see.
1) Worrying about the radio's input impedance is of little value

Of course. Wasn't me who was worrying about it, once I learned a bit about
it, some weeks back. I recently pointed out that striving to use 50 ohms for
an SWL setup that had undetermined impedances didn't matter to me. Am I wrong
both ways?

2) The choice of coax won't make much difference - performance wise, but
copper braid is much easier to solder to.

True. This is something I pointed out, several times. I also pointed out that
given the want to try things, a cable that can be reliably reused is better
than one that can't, so a fragile cheap foil screened cable is more trouble
than its worth.

3) A simple wire antenna at the end of the coax should be sufficient

Maybe. I'll be trying that. There's no room out there to run it without
bringing it close to buldings so to get anything decent it's going to have to
be vertical, so that immediately has a few demands. Can't just shove it up
there, it has to be safe. Tenants tend to have binding conditions for putting
up stuff like that too.

4) A balun (or un-un for the picky) between the antenna and coax is
probably worthwhile. 9:1 or 10:1 won't make any difference.

I intend to try one. The exact winding ratio doesn't bother me that much.
What bothers me is that if I don't mention one someone does, and if I do, I'm
told I shouldn't use one. The degree of contradiction I see suggests I'm not
the only one with some rather vague ideas. I read posts by John Doty that
have persisted a while online in several places since he wrote them. They
make sense, so I'll try them. They basically aim to reduce peaks and nulls in
sensitivity for various points in the HF bands.

5) Figure out what you are going to do about lightning protection.

Already have. It will go direct from antenna to ground through a winding,
there will be no direct current link from antenna to coax. The coax also will
have a 1:1 ferrite transformer at the receiver end.

6) Rather than spend weeks sorting out the details, string up some wire
and listen to the radio.


A simple wire direct to the radio doesn't help here. I'm in a basement, in an
inner city valley. Too much building around me, too much RFI, and too much
scaffolding too, major works being done to the building by the landlords.
Until I can get some undisturbed access to the back yard to wire an antenna,
I have no choice BUT to think of what I can do. The moment actually trying
stuff becomes easier than living with that and reading and posting online,
then I'll do it. I've bought a few things, coax, toroids, a cheap whip mast,
but there's not much I can do out there with anything yet.

One thing I've learned is that for every bit of informed advice, a bit of
informed contradictory advice will be found. Considering how easily people
give vent to it, it seems wise to ask and watch the answers and make up my
own mind. I also prefer to measure three times and cut once. It's usually
cheaper. I have plenty of time and not much money.

Not really. A few tens of metres of cable whose cost is not more than 3
times the cheapest of satellite coaxes, and whose total cost is less
than half the lowest cost of that radio when found second-hand, is
hardly overdoing it.
I think the point is that radio is very much under-doing it!!!


Why are you so set against that radio? A lot of people like it (some of them
enough to modify it rather than replace it). What do you recommend? And how
much would it cost? This thread wasn't about that radio but this is worth
pursuing, you seem to have a strong feeling about it. I just bought it
because it seemed like a good cheap base to start from. (Not cheap if I'd had
to buy new, but I purposely avoided that).

It is really more the difference in consideration between the coax and
the radio that strikes me. You are making a huge fuss over the coax, but
appear to have little consideration over the radio which is a far more
important issue. You seem to be set on the Sagen when it is is far from
the best solution, but nit picking over the coax, which in reality most
likely won't make a shred of difference.

It is a perfectly adequate radio for what it was designed to be; a
portable that you take away on holiday to listen to BBC world service
on, but as for using it for anything more it is lacking.

Even you admitted in an earlier post that it was overloaded by anything
more than a whip antenna!!

You would be far better off buying a dedicated HF receiver or a
transceiver with a far superior performance. They are available on Ebay
as well.

Jeff

Jeff wrote in :

It is a perfectly adequate radio for what it was designed to be; a
portable that you take away on holiday to listen to BBC world service
on, but as for using it for anything more it is lacking.


Lacking what, specifically? I wanted a general purpose radio with full AM
coverage to 30 MHz, and I wanted it to be cheap and portable. Then I wanted
to give it a decent chance of getting signals when I'm not carrying it
around.

As for a radio that that is only fit for getting BBC World Service, are you
sure you're not confusing the ATS-909 with whatever Sangean's original was,
as cloned by Roberts with model R9921? That really IS a basic radio designed
for that purpose, the ATS-909 does more.

Even you admitted in an earlier post that it was overloaded by anything
more than a whip antenna!!


Not the point. It's easier to attenuate than to do almost anything else. Even
the radio itself can do that.

You would be far better off buying a dedicated HF receiver or a
transceiver with a far superior performance. They are available on Ebay
as well.


If you know of any that fit my description above, please name them.

Lostgallifreyan wrote:
Jeff wrote in :

It is a perfectly adequate radio for what it was designed to be; a
portable that you take away on holiday to listen to BBC world service
on, but as for using it for anything more it is lacking.


Lacking what, specifically? I wanted a general purpose radio with full AM
coverage to 30 MHz, and I wanted it to be cheap and portable. Then I wanted
to give it a decent chance of getting signals when I'm not carrying it
around.

Chiming in late on this one.

The antenna isn't usually the limiting factor on modern radios. You'll
likely do as well with a random wire as a seriously engineered system.
Since you're only receiving, this is the case.

If you are wanting 500 KHz to 30 MHz, and you want full coverage, you'll
be hard pressed to beat a random length dipole and maybe give yourself a
little tuning cap on your end if you like. Just put up as much wire as
your space will permit, and there you go. This assumes that you use
ladder line to feed, not coax. For such a wide range antenna, ladder
line is the way to go.

That's going to wring out just about the last bit of performance you can
expect, unless you want to go to the bitter edge and construct
directional antennas. At the 500 KHz end, that will be a tad difficult.

Now for your application, the performance difference between a chunk of
wire, my random length dipole, and some directional gastraphagus will be
surprisingly little.

Use, or do not use the advice.

- 73 de Mike N3LI -

Lostgallifreyan wrote:
Jeff wrote in :

It is a perfectly adequate radio for what it was designed to be; a
portable that you take away on holiday to listen to BBC world service
on, but as for using it for anything more it is lacking.


Lacking what, specifically? I wanted a general purpose radio with full AM
coverage to 30 MHz, and I wanted it to be cheap and portable. Then I wanted
to give it a decent chance of getting signals when I'm not carrying it
around.

As for a radio that that is only fit for getting BBC World Service, are you
sure you're not confusing the ATS-909 with whatever Sangean's original was,
as cloned by Roberts with model R9921? That really IS a basic radio designed
for that purpose, the ATS-909 does more.

Yes, but you were not talking about the other bands that it covers, you
only mentioned HF.


Even you admitted in an earlier post that it was overloaded by anything
more than a whip antenna!!


Not the point. It's easier to attenuate than to do almost anything else. Even
the radio itself can do that.

So why are you so worried about the co-ax and SNR, if you add an
attenuator in order to make the radio work properly you will also
attenuate any interference (and degrade your SNR).


You would be far better off buying a dedicated HF receiver or a
transceiver with a far superior performance. They are available on Ebay
as well.


If you know of any that fit my description above, please name them.

Virtually any comms receiver will give you coverage of AM to 30MHz, many
also have Band 2 vhf as well, they are too numerous to mention, but have
a look at this link and pick the ones that actuall have good RF performance:

http://www.eham.net/reviews/products/8

Jeff

Jeff wrote in
:

Yes, but you were not talking about the other bands that it covers, you
only mentioned HF.


Fair enough, though I had mentioned it in earlier posts.


Even you admitted in an earlier post that it was overloaded by
anything more than a whip antenna!!


Not the point. It's easier to attenuate than to do almost anything
else. Even the radio itself can do that.

So why are you so worried about the co-ax and SNR, if you add an
attenuator in order to make the radio work properly you will also
attenuate any interference (and degrade your SNR).


Because I want to reduce the noise from stuff in the bulding compared to
whatever hits the whip antenna. Sure, attenuation might reduce SNR in a noisy
resistance (or subsequent gain stage) but NOT due to due to simple shrinkage
of scale (R = Ratio...), but that's why I want to get the SNR higher to start
with. It's the separation of internal noise signals from external wanted
signals that matters, same as for anyone using coax. Surely it's not suddenly
wrong because I'm doing it? If so, this isn't about science anymore.

If you know of any that fit my description above, please name them.

Virtually any comms receiver will give you coverage of AM to 30MHz, many
also have Band 2 vhf as well, they are too numerous to mention, but have
a look at this link and pick the ones that actuall have good RF
performance:

http://www.eham.net/reviews/products/8


Thanks, that will be useful. The ATS-909 is just a starting point. I want to
have tried it, even if I just sell it on. (Was why I bought it used, that way
I won't lose out).