"Pete KE9OA" wrote:

Hey Eric................anytime you have any questions, feel free to shout
me down, and I will be glad to answer them as clearly as I know how! The
coolest thing about knowledge it that it can be shared. Someday, I will
write a comprehensive book all about radio design...............I just need
to learn more than the
.00000000000000000000000001% that I know right now!

Pete,

Thanks for the offer! We've talked in the past, but I must say that
part of the problem is being able to frame the question coherently.

Take care,

Eric


Pete

"Eric F. Richards" wrote in message
...
"phil " wrote:

hi Eric:

i am responding here as my reader ate the thread...

Quite true, but that's not what you said -- you said it was
"resonant." A nit-pick, perhaps,

at 3/4 wavelenghts resonance is at 736-kHz. as a 2 wavelengths beverage:
1.9-MHz. your antenna is quite capable on MW.

Oh, I don't argue *that*, I just argue that it wasn't resonant.

Not that it matters, really, my WR-G303i reports its signal strength
as 30 mV 120 miles away on a 400 foot wire broadside to the antenna.
Flamethrower, indeed.

As for the "flamethrower" at the end of the wire, they are in
violation of 47 CFR 22.369, which explicitly lays out the field
strength limits on Table Mountain. They may get grandfathered in, but
now that the feds are reopening Table Mountain for NIST projects, the
local HDTV wannabes are chafing at the restrictions -- even though
their antennas would be about 40 miles away.

what frequency are they on?


Dunno. I don't keep up with the local doings of the broadcasters
much. I assume they are in the old standard TV UHF band; 47 CFR 369
says that from 470 to 890 MHz, field strength on Table Mountain must
be less than 30 mV/m.

radios are black boxes: feed them signals within specs and they perform
predictably. ICOM probably left off the LW BPF to save $1. companies are
cheap.

Actually I got word from someone who said that the '75 was considered
a work in progress that never progressed.

i know what the R75 is and is not.

Then all I ask is that you remember that when you brag on it. Good
bargain? definitely. Ultimate radio? No.

i am lucky to
have Pete as a mentor.

That you are. I wish I was fluent enough in electronics to be able to
speak the same language as Pete.

if you gain access to that antenna try your RX340
and bring along a 7030 owner.

No radio is perfect; the '7030 wouldn't hold up out there... To me
the question would be whether or not the '340 would.

Eric

--
Eric F. Richards,
"Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940


--
Eric F. Richards,
"Don't destroy the Earth! That's where I keep all of my stuff!"
- Squidd on www.fark.com

Pete KE9OA wrote:

The only way that this should happen is if either the receiver is very
conservatively rated (do we know exactly what method was use to make this
measurement?), or if the measurements were incorrectly done. I am not sure
that real world performance would reflect those measurements, unless you are
in an area where there are several strong signals that are only 5kHz apart.
When I am measuring the overload point on the receiver that I am developing,
it is very easy to drive the system into overload with a signal generator,
yet with a 100 foot longwire in the presence of three 50kW MW broadcasters,
no overload is present.
I think that specs do tell the story, if the measurement system is properly
set up.
As an example, on one project, I needed to make some desense measurements
from 5kHz to several hundred MHz away from the desired signal. The desired
signal level was -140dBm. Using an HP8657 or an 8640B, the broadband noise
from these two units was so high, even a 300MHz away from the desired
signal, that I had to run the generators through a K&L tunable filter. The
only generator that was slightly usable was an HP8642B. This is the one that
uses the Modulated Fractional Divider, with the Sigma-Delta modulation.
In reference to you statement about the receiver working better than its
rated specs, I just don't think so, unless as I said earlier, the
measurements were done incorrectly. The only way to really to a close-in IP3
measurement is to run the interfering signal through a very selective, deep
skirted crystal filter. You need the interfering signal to have almost
non-existant close-in phase noise; otherwise, the measurement is
meaningless.

Pete,

As you know the receiver testing for 'Passport' is done by Sherwood
Engineering. Do you know anything about the equipment they use and how
the test specs are generated?


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hi Telamon:

Actually I got word from someone who said that the '75 was
considered a work in progress that never progressed.

That's an understatement if I ever heard one!

Welcome to the real world. Engineers will play with a design until they
are happy with it but management runs the show. As soon as the pointy
haired boss thinks that the design has met its goals the effort ends.

sounds like the voice of experience.

regards,
phil

hi starman:

As you know the receiver testing for 'Passport' is done by Sherwood
Engineering. Do you know anything about the equipment they use and how
the test specs are generated?

go he http://www.mini-circuits.com/application.html

regards,
phil

hi Telamon:

You can mark the group unread or un-subscribe and re-subscribe
to the group to get all messages on the news server.

thanks, i tried. the HDD has errors.

Blindly reading specifications can lead you astray on how the
radio will perform. Some measurements require the radio be in
a non-optimum reception state.

there is also creative spec writing. i'd rather view a schematic, do you
have the RX340's?

I'm going to play devil's advocate and ask the question "why do some
radios work much better than the IP3 @ 5KHz measurement would indicate?"

during usage, antenna can help: if we use a LW loop and that station 5 kHz
away is being nulled by 50 dB because of its direction then we've solved
the problem before it got inside the radio.

regards,
phil

hi Eric:

Oh, I don't argue *that*, I just argue that it wasn't resonant.

if you knew that then why use this antenna for LW?

Not that it matters, really, my WR-G303i reports its signal strength
as 30 mV 120 miles away on a 400 foot wire broadside to the antenna.
Flamethrower, indeed.

30mV at what frequency? can you fault the R8B and R75 for overloading?

Dunno. I don't keep up with the local doings of the broadcasters
much. I assume they are in the old standard TV UHF band; 47 CFR 369
says that from 470 to 890 MHz, field strength on Table Mountain must
be less than 30 mV/m.

that PAR LPF should severely attenuate UHF. spectral analysis of that wire
is needed. low frequencies or potent RF energy can cause PIN diodes to
rectify.

No radio is perfect; the '7030 wouldn't hold up out there... To me
the question would be whether or not the '340 would.

the 7030 uses an SD5400 first mixer and has 40 dB of attenuation on tap...
add a $50 homebrew LW BPF: your RX340 will overload first. either way an
R75 hooked to a LW loop will hear more NDBs.

Eric, you remind me of Captain Ahab, fighting that whale of an antenna,
Moby Dick. man versus nature, a classic... but the SOB already bit off your
leg. shake the obsession... build a LW loop.

regards,
phil

"phil " wrote:

hi Eric:

Oh, I don't argue *that*, I just argue that it wasn't resonant.

if you knew that then why use this antenna for LW?


Sigh... round and round we go... because it was very effective for my
needs, specifically picking up NDBs east of the site. Which it did
very well.

Not that it matters, really, my WR-G303i reports its signal strength
as 30 mV 120 miles away on a 400 foot wire broadside to the antenna.
Flamethrower, indeed.

30mV at what frequency? can you fault the R8B and R75 for overloading?

....what are you, totally thick or what? The MW station that was
causing the problems.

Dunno. I don't keep up with the local doings of the broadcasters
much. I assume they are in the old standard TV UHF band; 47 CFR 369
says that from 470 to 890 MHz, field strength on Table Mountain must
be less than 30 mV/m.

that PAR LPF should severely attenuate UHF. spectral analysis of that wire
is needed. low frequencies or potent RF energy can cause PIN diodes to
rectify.

The PAR LPF has no relevence to the federal regulations regarding
Table Mountain. What's your point? HDTV broadcasters at Lookout
Mountain are griping about the regs. My point, in case you missed it,
again, is that the flamethrower is in violation of the regs in 47 CFR
369.

No radio is perfect; the '7030 wouldn't hold up out there... To me
the question would be whether or not the '340 would.

the 7030 uses an SD5400 first mixer and has 40 dB of attenuation on tap...
add a $50 homebrew LW BPF: your RX340 will overload first. either way an
R75 hooked to a LW loop will hear more NDBs.

Of course. The R75 solves all. Can't imagine that if you use your LW
loop with another radio, that it'll outperform that R75, can you?
Come on, this is really simple. Take whatever crutches you add to
your R75, apply them to nearly ANY other radio on the market, and
it'll leave your R75 in the dust. (Notably, your dream radio, the
Racal 6790, would be left in the dust as well. What's your affinity
to radios with crappy front-ends?)

Eric, you remind me of Captain Ahab, fighting that whale of an antenna,
Moby Dick. man versus nature, a classic... but the SOB already bit off your
leg. shake the obsession... build a LW loop.

Actually I'll probably purchase what Pete comes up with, since his
loop probably will have a low NF and resistance to overload. Just a
guess. We'll see.

regards,
phil

So, what's the deal with the R75 schematic on Yahoo? I've been trying
to retrieve it for a week and the server acts dead. Is Yahoo that lax
in running their servers?

--
Eric F. Richards,
"The most likely way for the world to be destroyed, most
experts agree, is by accident. That's where we come in;
we're computer professionals. We cause accidents."
- Nathaniel S. Borenstein

Eric F. Richards wrote:

[...]
Dunno. I don't keep up with the local doings of the broadcasters
much. I assume they are in the old standard TV UHF band; 47 CFR 369
says that from 470 to 890 MHz, field strength on Table Mountain must
be less than 30 mV/m.

that PAR LPF should severely attenuate UHF. spectral analysis of that wire
is needed. low frequencies or potent RF energy can cause PIN diodes to
rectify.

The PAR LPF has no relevence to the federal regulations regarding
Table Mountain. What's your point? HDTV broadcasters at Lookout
Mountain are griping about the regs. My point, in case you missed it,
again, is that the flamethrower is in violation of the regs in 47 CFR
369.


Ack! phil completely drives me to distraction. The above two entries
should read 47 CFR 22.369 Part 22, 369.

I should've kept my R75 and put a "Hello, my name is phil" tag on it
so I could give it a good kick every time he posts more pro-R75
drivel...

hi Eric:

...what are you, totally thick or what? The MW station that was
causing the problems.

at what *frequency* is that MW station transmitting?

Of course. The R75 solves all. Can't imagine that if you use your LW
loop with another radio, that it'll outperform that R75, can you?
Come on, this is really simple. Take whatever crutches you add to
your R75, apply them to nearly ANY other radio on the market, and
it'll leave your R75 in the dust. (Notably, your dream radio, the
Racal 6790, would be left in the dust as well. What's your affinity
to radios with crappy front-ends?)

the R75 was used to drive home a point: ANY tabletop using the LW loop i
suggested will outperform your antenna. only you cannot admit you were
wrong. thinking is a crutch! rip on the 7030 and Racal all you want genius.
who could not figure out that a simple $50 homebrew LW BPF in front of
either will smoke your $4000 RX340 in terms of IP3, dynamic range, phase
noise, ultimate rejection, etc. explain how your radio will leave any
tabletop "in the dust" when both are hooked to a LW loop? quote specs.

regards,
phil

I should've kept my R75 and put a "Hello, my name is phil" tag on it
so I could give it a good kick every time he posts more pro-R75
drivel...

pandering Captain Ahab? when Moby Dick overloaded an R8B and R75 you just
blamed the radios: "Get a real radio, and notice the difference. And if you
can't afford a real radio, get a Drake." so Steve, Les, Ken, me, and others
told you to stick it. instead of building a LW loop you went out and
"showed all us idiots" by buying a $4k radio LOL. what did you ask those
TenTec engineers Eric? directions to the bathroom? in the words of
President Bush: "THE GAME IS OVER"

regards,
phil