I am not into LW or MW but a friend who is a new SWL is.
He found two very usefull additions to his R2000 and wire antenna
setup.
http://www.kongsfjord.no/dl/Antennas/MW%20Filter%20no3.pdf

http://www.bobsamerica.com/swl
orhttp://us.geocities.com/amdxlog/index.html

The first unit was designed by Dallas is for MW but Will made some
simple changes, larger, (more inductance) colis and it works very well
down to ~100KHz. It needs some refinement for such a junp in design
frequency but it is very good at rejecting off channel RF.

The last 2, same info just different web pages by Robert Betts, work
very well as a preselctor also. While Robert uses a MMIC, I found that
Lankford "Ultra linear amplifier" to work much better as in no IMD
issues.
http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%20Amplifiers.p df
I also found that for most, 99%, an amplifier is not needed and if I
where
going to build one, I would build it test it and only add the amplifier
if needed.
Guy in the pacific NW might well use an amp, I suspect that for most of
the
rest of use the local noise floor will obviate the need for an amp.


For operation from 100KHZ through 30MHZ the Betts desing is very good.
However if onc is concentrating on MW and LF then Dallas' design is the
hands down winner. Will has both. And I thoguht I was nuts.


Will is also experimenting with Dallas' "Phaser" to allow a synthetic
steerable
antenna. Note don''t add the vernier yet, Dallas told me it might need
some
change. The basic unit is easy to build and offers excellant
performance. A
little touchy without the vernier, but a very nice unit. It even works
very well built
as a bread board.

While Dallas suggests using matched antennas, Will is using presently
mismatched
antennas, one modified North Country that consists of 2 NC singled
ended antennas
wired for dipole operation simliar to Dallas' active dipole and one
true Lankford active
dipole. There are significant differences and the NC is very prone to
overload and IMD
issues. The Lanford active dipole has no detectable IMD in from my 2
local problem
stations, 770KHz and 1240KHz. The 1240 station is 3 times as far from
me as the
770, but they sure are a good test! At some point in the near future I
hope to have
4 complete Lankford active dipoles to improve phaser performance. A set
for Will
and a set for me. I do get some grunge from LORAN C at 100KHz, but I
think that
is an receiver issue. Will is experimenting with combinations his wire
antenna
and either dipole. Every combination works, but using the 2 dipoles
works best for
him.

I am not used to being able to steer an antenna on HF to peak, or more
likeley null
RFI, a signal.

Terry

Excellent info Terry. I am using a similar arrangement for LW signal
enhancement but plan to take some ideas from the designs you presented.
I use a heavily modified Grove Tune 3 passive preselector. I have
modified the LW/MW coils and employed better output impedance matching.
I am presently experimenting with an old Ralph Burhans LW preamp
circuit with input low pass filter which works very well also. I am
finding that the whole trick to LW reception with an end fed wire
antenna (assuming the wire is at least 120' or more) is the impedance
matching to the coax (so what else is new!!!) since the antenna is in
the tens of K ohms at LW. A significant improvement in reception is
realized if the antenna is 250 feet long and of course if you can get
more than this it's even better. When I was in S. CA I had two 1/2
mile long wire antennas that stretched over bushes and the ground into
the local national forest. LW reception was utterly phenomenal,
however, the wires were directional primarily off the ends (Beverage
effect?), hence I had one running N/S and one E/W. Since my lot here is
only 1 acre I must suffice with 250 feet. I am, however, seriously
eyeing the nearby wash as a possibility. I'm also considering a large
horizontal wire loop around the property lying on the ground. Any
comments on the latter idea would be appreciated.

Frank

wrote:
Excellent info Terry. I am using a similar arrangement for LW signal
enhancement but plan to take some ideas from the designs you presented.
I use a heavily modified Grove Tune 3 passive preselector. I have
modified the LW/MW coils and employed better output impedance matching.
I am presently experimenting with an old Ralph Burhans LW preamp
circuit with input low pass filter which works very well also. I am
finding that the whole trick to LW reception with an end fed wire
antenna (assuming the wire is at least 120' or more) is the impedance
matching to the coax (so what else is new!!!) since the antenna is in
the tens of K ohms at LW. A significant improvement in reception is
realized if the antenna is 250 feet long and of course if you can get
more than this it's even better. When I was in S. CA I had two 1/2
mile long wire antennas that stretched over bushes and the ground into
the local national forest. LW reception was utterly phenomenal,
however, the wires were directional primarily off the ends (Beverage
effect?), hence I had one running N/S and one E/W. Since my lot here is
only 1 acre I must suffice with 250 feet. I am, however, seriously
eyeing the nearby wash as a possibility. I'm also considering a large
horizontal wire loop around the property lying on the ground. Any
comments on the latter idea would be appreciated.

Frank

I have always had major problems with antennas longer then 100 to 150'.
The strong out of band MW signals even cause a R390 front end to fold.

Have you considered a low pass fitler to reject everything above
~500KKHz
before your tuner?

And as Burhans pointed out a "good" active antenna can often match a
long wire.
Will is having much better succes with his active antennas then the
~100'
long wire.

One winter, 1977-78 we had enough snow to last a lifetime. After 3
weeks with
3' of snow on the ground I gave up trying to erret a new antenna, I had
just gotten
married and had NO antenna. So I laid about 100' of #18 and it worked
fairly welll.

Let me do some more thinking.

Terry


Terry

I've used an LF Engineering L-400B active whip in the past and it would
pretty much out perform longwires less than about 1000 feet. IT's only
problem was intemod and overloading issues if MW stations were nearby.
Mine actually wore out due the intense UV from the S. CA and AZ sun. I
still have the electronic guts and should probably rework it for use
again. I do have the PAR Inc. high and low pass filters and they work
great on 50 ohm lines to eliminate intemod after a passive tuner.
Despite the local MW stations I don't have any problems at night and I
can force the situation most of the time during the day as long as
there are no amps in the signal chain.

Frank
Tucson




I have always had major problems with antennas longer then 100 to 150'.
The strong out of band MW signals even cause a R390 front end to fold.

Have you considered a low pass fitler to reject everything above
~500KKHz
before your tuner?

And as Burhans pointed out a "good" active antenna can often match a
long wire.
Will is having much better succes with his active antennas then the
~100'
long wire.

One winter, 1977-78 we had enough snow to last a lifetime. After 3
weeks with
3' of snow on the ground I gave up trying to erret a new antenna, I had
just gotten
married and had NO antenna. So I laid about 100' of #18 and it worked
fairly welll.

Let me do some more thinking.

Terry


Terry

wrote:
I've used an LF Engineering L-400B active whip in the past and it would
pretty much out perform longwires less than about 1000 feet. IT's only
problem was intemod and overloading issues if MW stations were nearby.
Mine actually wore out due the intense UV from the S. CA and AZ sun. I
still have the electronic guts and should probably rework it for use
again. I do have the PAR Inc. high and low pass filters and they work
great on 50 ohm lines to eliminate intemod after a passive tuner.
Despite the local MW stations I don't have any problems at night and I
can force the situation most of the time during the day as long as
there are no amps in the signal chain.

Frank
Tucson



You might want to review the Burhans active antenna and think about
adding his
MW rejection filter. It works very well with most JFET active antennas.
There
was something odd about the Burhans LF match box. It has been too
darned
long, but I think one of the torroids he used, or his magnetic bias
scheme
caused some serious IMD. I have most of the RE Burhans stuff, but no
longer
have the one on the LF matcher. Maybe I can stop by the engineering
library Sat
and pull that one from microfilm.

Will is having great success with the Lankford active dipole, the AMRAD
is a
rather poor copy/clone of Dallas work and in the dipole mode, IP2 goes
up several
dBm. And you can rotate the thing to peak a signal or null a noise
source. Ron
Hardin uses several sets of McKay 100? single ended actives antennas
with multiple phasers to knock out multiple noise sources.

What receiver are you using? Must have a very tuff front end to survive
in the RF
hell you are discribing.

A friend once ran several hundred feet of scanged CATV
hardline down a drainage ditch and under a culvert to reach some nearby
woods
where he errected a ?3000' antenna pointed great circle at England. He
really
wanted MW transatlantic DX. He used a taped inductor and a ground rod
with
several hundred feet of radials and it was killer. At lower frequencies
coax loss
can often be low enough to allow such odd stealth setups.

Terry