Topics

16

General Radio Discussion / Short Commercial AM Broadcasting Antennas

« on: May 18, 2021, 1655 UTC »

Hey All,

Just ran a few of these for grins :

WCNL ,1010 Newport ,NH :1/4 wave would be  231 ft. They run 10 Kw day on   63 ft (!!) of guyed tower with a Zillion panel antennas (cell/ 800/900Mhz ??) attached . AM almost looks like an "afterthought"  and that it seems most of the  dough is coming in  from repeater rentals. LOTS of   juice lost  on this  antenna  , but I still   hear them daytime ( fair to weak )
 through hilly  terrain / poor ground  conductivity at around 113 miles away.

WZBR , 1410 Dedham, MA : 1/4 wave would be 165 ft. They run 2Kw day into free standing 75 ft fiberglass whip (helical wound inside). I'd love to see this one in 75 MPH winds ! Fair signal at 9 mi ,  terrain path  maybe not too bad.

WJIB 740 Cambridge MA : 1/4 wave would be 316 ft. They run a 285 ft free standing tower, so it would be  thrown into our "not too bad department" at  31 ft short of 1/4 wave.Line of sight "Band Bully", even at 5 W night time  power at around 4 miles out.

Can anyone else give  any examples that you know of, the shorter the better. Maybe 1/8 wave or less ?   I am just curious how LOW some of these guys limbo and STILL make it "work", but obviously WITH a serious  electric bill as a "penalty".

FWIW /  a bit OT, I have worked out to 27 miles using  a high mast mounted 50 ohm resistor with very short leads soldered on   75 ft of 9913 (a "sort of"  "near isotropic " radiator   ?? ?)  on 440 Mhz FM. Rig output hyper low ,  got around  2 to 4 mW output  at radiator ?? QRPpppp- THAT was fun ! I also ran ridiculously low  outputs on 2 M SSB/FM as well.

K

17

MW Loggings / Hodge Podge

« on: May 17, 2021, 1145 UTC »

Hey All.

 From 5/16 and 5/17 -A mix and match of day and night, in NOISY apt  or in park across the street, using  Super Radio I and  basic Select-A-Tenna. Sorry about the sloppy report , but a wild weekend .I went to  BIG radio flea market,  much unpacking/testing goodies, etc, etc.

Day/  QTH : QRN quiet park - solid WFAN 660, WCBS 880 (etc)  and also 1620 pirate ( in full QSB). Tried for WINS 1010 but it copied WCNL on 1010 in NH instead (  I really want NYC daytime on 1010, so maybe a bigger loop next time). Broke off  as rain/ occasional  lightning approached.

Night /apt  my BEST CFZM 740 Zoomer reception to date. I had the  usual 740 Khz 1/2 second consistent  "beat flutter" and roller coaster propagation, but this time when Zoomer Zoomed, it REALLY Zoomed UP - VERY  BIG ! But as per usual , at times, it would completely collapse for extended periods. It's always very "moody" here with their null in my direction .  It's a  real study in night time BCB propagation.  Extremely touchy and exacting placement of rcvr and loop required ( ie down to around  1/8 to 1/4 " !!). The Zoomster is up  against monster local Co channel WJIB . Even when  the JIBer is  at night power (5 W), it "lights up the room" being  line of sight at a just a few miles.

KDKA 1020, WSB 750 ,CMLA /R. Progresso 640 all MIA.

Other misc goodies logged, but frankly, lost in the "blur".

Also just for giggles I did a bit of lightning "DFing" on 530 khz  comparing to IPhone lighting map.

I also found out my kitchen seem a BIT less noisy (FWIW).


K

18

North American MW Pirate Radio / UNID 1620 AM 1900 UTC 16 May 2021

« on: May 17, 2021, 1110 UTC »

Hey All.

5/16/21 ,1900 UTC, 1620 Khz (?), GE Super Radio I , Basic Select -A -Tenna (no jack)   tried for grins, but mostly not needed. QTH park across the street from my  (NOISY !!!) apt. Just 150 ft makes a HUGE difference, electrically much more  quiet there !

Some  loud Goth / very heavy screaming guitar ,  but also some really  soft stuff ( ex : a cover of   "Scarborough Fair" by a female singer).  Young/ Caucasian sounding announcer. At times full QSB ( in blasting full daylight) , so maybe a"short" NVIS skywave (??) at less than 200 mi (??). Who knows, could be "closer".  But rains/ with  occasional lightning began to approach  , so without a good ID I abandoned the "Dxpedition" (Hi).

I just bought this radio, so not sure how high it tops out, gotta run a sig gen  check when I get a chance . But it definitely  does have some "head room" - CHRN 1610 was an easy catch the night  before  ( up against local flame thrower WUNR on 1600) and it still  squeaked a bit higher than them. I think I had a TINY bit of play above the pirate as well, so I am going with 1620.Some say SR-1's top at 1630, but again , gotta check.

Web address sounded something like heardonradio.com (??) but it was no  good on Google.

WEDG ? Unsure of probability.

K

19

General Radio Discussion / Explosives "Resistant"/ Hardened Antennas

« on: May 12, 2021, 1238 UTC »

Hey All,

LONG shot on this one- but :

I am wondering about   pics  I saw MANY,MANY  years ago of an antenna in Israel. (If we could , please leave politics and "current events" out of  any replies- strictly  a technical discussion -thanks).

I believe that the Israelis had a "hardened" antenna  (if I recall correctly)  for AM broadcast. It consisted of  heavy steel I  beams welded in series  stood off on large insulators , very close to the ground (6' up ?) .There may have been protective earthen dikes around it as well.

Probably a miserable  pattern for local ground wave but maybe via NVIS- MAYBE ??  . But if one really cranked up the juice then tuned  and loaded it properly, I suppose it COULD  ground  wave  "radiate" MAYBE enough to cover a limited area ( ie maybe just  around Tel Aviv ?). If nothing else, a fascinating technical concept (re being bomb "resistant"), even if it was a real dog re power in vs. power out.  Transmitter was likely in a bunker.

I can't find a THING about this online and I can only imagine it may be long gone by now.

It also seems that Israel in general  is now completely off of the AM broadcast band for ALL (ALL) outlets and that Kol Yisrael is also long gone off shortwave (  anyone ,any info  ?).

Israeli Army Radio / Galgalatz now seems to be on FM only as well. Not sure if the I beam antenna was theirs or not for civil defense purposes. Also WAY, WAY back in the day, I THINK they were also  on shortwave, maybe using  SSB (anyone, any info,  frequencies used /mode ?).

I have personally seen "a sort of" "hardened" antenna  on the Maginot Line Fortifications near Bitche, France. Large steel brackets on a vertical wall held a  large gauge   long wire antenna on heavy insulators. Certainly  not  nearly as beefy as an I beam antenna, but "tough enough" against small arms fire ( I guess) .

de K

20

MW Loggings / CFZM Zoomer 740

« on: April 28, 2021, 1202 UTC »

Hey All,

Zoomer in deep QSB, mostly weak (or gone) ,up to fair "at times". Up against local Co -Channel WJIB .

JIB is the "Giant Flea" here  at night.Their tower is only around 2.5 mi direct  line of sight, so even when at 5 W night time power, it's BIG.

Also noted (as always) was the infamous  "Zoomer Flutter" .As CFZM starts to rise up out of the mud, it begins to flutter up against JIB. This is not a"variable" rate propagation type of flutter.Instead it is  rock solid and is always  at "referenced rate " that is constant at around .5 seconds.My guess is that one of these guys is a few 10's of Hz off frequency, and causes this  interaction. (Any comments  ?).

  This Co channel  is always  fun , but a   challenge to null. The loop and the 803's ferrite ( X AND Y "origin" point)  both have to be in EXACT  position. 1/8 to 1/4 " fully makes or breaks Zoomer reception. It's really cool how tight it is.The Panasonic is tiny bit more forgiving due to a longer rod, but not by  much.

I doubt many folks can pull it out , at least in the immediate Boston area.

 I can only imagine how the big litz loop will play on this situation  and on other frequencies. Gotta finish the  "small" (16") "Test Bed" loop first,maybe this weekend (if my first "shot" on Friday doesn't make me sick).

Also noted KDKA, but not as good as the other night.The band seemed down a bit from earlier in the week.

K

21

North American MW Pirate Radio / 1620 Haitian Boston

« on: April 26, 2021, 1440 UTC »

Hey All,

4/20/21 1700 local  on 1620 Khz Haitian station  very strong in Creole near Franklin Park area of Boston. Not audible at my home QTH which is several miles away and also  behind hill (s).

This is the last (AM)  Haitian left that I know of (I didn't scan FM). All other frequencies in X band were  locally daytime quiet .

A few years back, Haitians dominated 1610 Khz  and above   with as many as 4 to 6  operating at once (at peak ) and another 1 or 2 in the upper end of the main band. All are gone except for this last hold out.

de NQC

22

Equipment / Shielded Loop (Come On , Feel The Noize)

« on: April 08, 2021, 1654 UTC »

Hey All,

I am a new guy here and figured I'd run this by folks.

I have seen shielded  loops in my travels over the years, but was always kind of puzzled on exactly how they are supposed to work.The "usual" description is that the loop  "responds" only  to the magnetic aspect of a "signal" and is therefore less noisy. Hmmmmmm.

Maybe my understanding of RF physics is WAY off . I THOUGHT that a "signal" had both a magnetic aspect and a voltage aspect and that they were basically  a "representation" of the same thing, at the same energy level ,inexorably bound ,but 90 deg out of plane to each other.

SO- any "signal " recovered ,whether by magnetism or voltage, should be equal in energy (or so I  would THINK). But (apparently/obviously) this isn't true or no one would ever bother to shield a loop, right ?

Concept :A shielded loop has a gap in the shielding so the turns aren't completely "shorted". That I  get.

The part that throws me off is how "undesired" or "desired" "signal" can be "cherry picked" from it's  voltage vs magnetism to optimize "results".

Is "undesired" signal (re shielded loops)  taken to mean arc noise, such as a local leaky power line insulator or (at a stretch lightning crash "arcs") ? Perhaps "device" noise, such as plasma TV's , switching power supplies, dimmers, etc, etc are not in the "arc" class of noise and thereby irrelevant re noise reduction discussion of a shielded loop.Don't know.

Also the  TYPE of loop construction  seems to be important. The ones I have seen seem to be  shipboard LF DF loops with a BNC female unbalanced (50/75 ohms ?) on the base box. Epoxy seems to fill the shield top  gap. Not sure about the  internal winding, but I would THINK they are scramble wound / non spaced / untuned low Q affairs (correct ??). Basically patch your receiver's coax in and "deal with it." Maybe this is  OK at 200Kc, but at the  AM Broadcast "transition point" (above 1000 or 1200 KC) maybe another story.

 My recent flop (in the apt.)was to try and aluminum foil wrap (with a gap)  onto my 24" X 24" (scramble wound) Low Frequency Engineers LF- 600S (for 7 KC "Whistler" use), just for chuckles. If anyone desires to hear raging loud 60 Hz noise, this is the antenna for you  ! It does work awesome in quiet QTH's though. Basically, an abject failure with no 60 Hz reduction at all. Maybe it was  simply in  too strong a 60 Hz field ?

So, circling back,   (after 53 years of "playing around" with the radio hobby)   I am stumped on how  shielded loop "deep" theory actually works.

To make matters WORSE, I have 13.8 Kv at 20 ft on one side and 13.8 at 35 ft (with pole pig) on the other. I live on a corner and am clobbered from two different 90 degree compass headings (bad). These lines leak fairly bad at times, especially when wet.Got a run around from power co, even I know I realize they are "supposed" to respond.  I also have device noise (plasma, et al) from the other apartments.

To FURTHER complicate things, I only have ferrite receivers right now, the 50 ohm Icom stuff ( R-70, R-71a, IC-735, etc, etc) is all long gone. I have no options for roof antennas anymore (I USED to have a fairly quiet  40 M dipole, a 85 ft long wire, a HiFer  tx dipole,a 6 M SSB  dipole, VHF/UHF ham  verticals ie various Diamonds ,QRPP HF/VHF/UHF,etc, etc). No more roof access.

All the loops I have made (so far) were single winding for direct couple to Ferrite receivers. Nothing   has been built (so far) with  a stand alone tuned primary/secondary pick up loop arrangement for a 50 ohm unbalanced coax lead to a  rig.At  former low noise QTH's  I had preferred that my loops (if possible) can be tuned to peak and not just unspaced low Q scramble wound just  for the sake of being able to be shielded.That was before I moved to noiseland though.

Buying another 50 ohm rig for BCB / LW is not totally out of the question , but I am not sure if there is any way other  to go.

There is also the factor (FWIW) that my Fe receivers may also be  picking up undesireds directly (to a degree) by their internal Fe rod, and a loop may only "boost" this problem.

I had also have  heard this very old vague   saw that "noise" in an RF amplifier has a tendency to get get amplified more than "desired" signal (baloney ?).

FWIW, I do almost NO HF listening now, I  pretty much roam from around  1720 KC down to 7 Kc.

I DO get a fair amount of DX, ie  IL,TN,KY, NC nearly every night, WSB (usually fair or worse) some  nights , R. Progresso Cuba 640- fair maybe one or twice month, especially in winter. Also recently snagged WQFG689 1710 NJ ,along with some new X banders.

So it could be worse , but would like to improve my limited situation if possible .

QTH Boston MA (noisy) apartment. Currently using Panasonic 840 or Sangean ATS 803A  with the  basic unamp'ed /no output jack Select-A Tenna. Currently a small open wire /directly coupled single winding  loop is under construction , two others planned (a medium and a very large). A number of discrete  circuit board projects planned ( maybe a Q multiplier, transistor  receivers, crystal sets etc).  Used to be into VERY high Q crystal set Dx, when  I had a long wire.

Also a  VFR private pilot , worked for NWS as volunteer at climate  research station for 10 years  and into ANYTHING on or  near Earth ,"far" stuff too- but not as much.

Anyhoo, that's my sad story and I'm sticking to it.

ANY help or input is GREATLY appreciated.

de NQC