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Messages - NQC

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136
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




137
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

138
Equipment / Re: Best MWDX antenna?
« on: April 20, 2021, 1556 UTC »
Hey All,

More  random comments :

Quite an interesting concept to think of a loop as a   "pre- selector".   Also ,a loop  certainly may not be a "substitute" for a serious outdoor wire antenna (of any type). A supposed rule of thumb ( not sure if exactly true or not ), If- a loop has ie, 100 ft of wire, even if well built,it  supposedly grabs only  1/10 of the energy of a well built  outdoor 100 ft long  antenna (comments ?). But Q and directional ability  are the advantages.

I have used both and REALLY liked having both at my disposal,way  back when. Unfortunately, any serious outside wire antenna is now out of the question for me .So it's loops or pretty much nothing.

 I suppose each  QTH is different re the type of noise encountered, operator's  "goals" , etc. One size (re anything) may not fit all.

Obviously one main   focus , IMHO, is Q .Not matter what you build, be it small tank ,loop or long wire or ground run. And at least in my experience with my (long gone) ultra high performance  DX crystal sets, the takeaway is  save every tiny bit of Q you can. It adds up.

Insulate and insulate again. Radio "loves" air- not solid surfaces. I even used to air  stand off ground runs until it reached rod. Maybe overkill to some, but Q bleeding seems to hide in some  unexpected places.

In my experience any  serious home brew tank/loop,etc,  starts with  the var cap. It is the first (and maybe the worst) place things can go wrong,IMHO .To me , nothing can replace a 500 pf 4 gang ceramic ( very important that it be ceramic )wired 2 gang as one leg, two gangs as the other. This will eliminate rotor loss. Such caps are often found in old signal generators. If purchased on line, they can be expensive. But WORTH it. I was cheap with mine and enclosed them in airy styrene boxes with  ceramic stand off  insulators  and quick solder  terminals. That way I can hard solder them into whatever project I feel like and not have to buy 12 of them (ha, ha).  6:1 (or better) Ball drives and shaft insulation  , panel  shielding, etc, are musts with theses caps. A definite "investment".

4 gang ceramic did well quite  even with solid copper  #20 cotton covered wire coated with poly. Such coils with bakelite var caps were noticeably down , even just by ear.4 gang ceramics with 660/46 litz are  simply stunning.

Back in the day, I took one of my 660/46  ferrite tank coils off the xtal set and coupled the long wire   to the Panasonic's ferrite.
With no ground wire on anything, the results were incredible. Station audio was pinched up really tight  and you would swear you were listening to a regen.The selectivity was   awesome. Using a ground knocked things down a lot.

 I guess any air  loop , tank , external ferrite bar coupler , etc are only as good as the components and insulation and the good practices/ techniques  used.

I gotta try another BIG Fe external coupler some time.I had SO much of this stuff before the "Great Purge" of 2019. I regret tossing  a fair amount of these  items (some of which which I MAY reacquire, maybe ) , but the   situation dictated it then .Oh well.

Also re air loops  used on 50 ohm receivers : I have always been a bit concerned (maybe unfounded) that it has loss written  on it (Unless you are talking Kiwa high dollar /50 ohm designed/  regen loops. I had a friend who had one.The performance would  blow you away).
 
I think it would have to be done right to (maybe) get it to work well . Just having a ratio'ed  secondary wound right on top of the tuned primary may not be so hot . My understanding , is that the pick up winding may also need to be  properly spaced away from the tuned primary as well as ratio'ed. On the AN -200 or a Select -a -Tenna with a jack, this isn't practical due to space  considerations . Just too big for a "grab and play" type of store bought antenna.

Even simply tapping an air  loop way down for 50 ohms may cause a (serious ?) Q reduction  re loading the loop ( comments ?). Admittedly, I have not tried this, so maybe I am not the guy to comment.

I'd  say  knowledge of RF physics is  at a "low  to moderate level " (at best) , so if I am off base on anything , I welcome correction for both myself and for the group to learn  from .

de NQC

139
MW Loggings / Re: Another WHAS maintenance outage
« on: April 19, 2021, 1237 UTC »
Hey All.

FWIW, WHAS was fair to good but also  up and down here last night.

QRM from local  band bully on 850 despite countermeasures ( 50 Kw at 10 mi- I am also  in gain portion of pattern).  Not sure how much else I would hear on 840 other than 'HAS anyways  due to fairly bad monkey chatter from 850.

A night of "typical" reception for 'HAS.


NQC



140
Equipment / Re: Best MWDX antenna?
« on: April 14, 2021, 1712 UTC »
Also all  sorts of  types of   counterpoise   and ground rods experiments-and- Shortish verticals with  evenly spaced out  loading coils  with  radials or screen  -or- rods or spaced out rods AS antenna-or-single rod AS antenna, etc, etc. ALL sorts of options re all different types antenna designs  and the  different types of noise being encountered,

141
Equipment / Re: Best MWDX antenna?
« on: April 14, 2021, 1644 UTC »
Hey All.
Alpard: 20X20 M is a fairly big area and without getting overly specific, I feel that a lot could be done in that size space.

Just to try something different, a number of years ago, I had reading about low noise (wire) antennas for HF/B'cast.
These sometimes required multiple grounds , multiple chokes, etc, etc. I never built any because I couldn't meet the specs required.
So a search for "low noise antennas" may get you somewhere.Perhaps you can quickly find the "class" of common mode choking wire antennas that I refer to here.

What wave lengths you'd want to construct these- perhaps there are different schools of thought as to how long to make them and how to construct them. Long has it's  has good points
but in an overloaded big signal and/or big noise environment maybe big isn't so great either, even re dx. Q is the key and a circuit that uses more variable capacitance and less inductance at the desired wavelength could be given some consideration. Also short 3 wire 20 or 30 ft  flat top spaced at 3 ft between  wires .It's all bonded on feed line end and  all open / NOT bonded  at the far end.

Feed line Shielding or feed line spacing will probably apply.Again, just a class or two of home brew inexpensive antennas could be tried for grins. Maybe they are for you, maybe not.

Not sure what may be worst of your issues: Arc/ power line noise -or-  local "device noise ( plasma TV's  noisy power supplies, etc) -or -local  broadcasts or other strong RF from off far away.
So your mileage , options and interests may vary.

Not sure if you have played with medium sized air loops (with /or with out low Z coupling loop/coax fed) . Or air loop just coupled to ferrite.True, it is a VERY small antenna compared to large out door custom arrays. But they have some  very interesting properties  and I have found them a lot  of fun to play with IF built well.

K

142
Equipment / Re: Shielded Loop (Come On , Feel The Noize)
« on: April 09, 2021, 2200 UTC »
Hey All.

Ray: I read up on common vs  differential and picked up some good points and interesting info from that pursuit.Interesting on how a  "signal" behaves at distance.I did not know that.

Chris: First of all - LOVIN' the website !  I read W8JI and found it to be quite good.

The one thing I keep seeing everywhere ( W1VLF, etc) is coax feed, which while I GET and certainly find  advantageous, doesn't apply to my current situation of isolated  loop to  receiver ferrite coupling.

It seems to me that if you run "wide open" (no coax), you are going to get your "clock cleaned" by noise.

The symmetry and elegance of the  construction  needed lends itself much more to an unbalanced feed scenario than open ferrite  and an open air loop.I don't think there is enough aluminum  foil on a  roll to bail me out of this ( Hi).

I suppose I could wrap the loop and an enclosed VC and try to run with it. But I also have concerns (maybe unfounded) that the open and spaced  windings might take a Q hit by being in proximity to Al foil, even if it IS non ferrous . It sort of seems to be barking up the wrong tree to   quiet down  a air coupled   air loop down by shielding. But even if the concept may be a non starter, I learned a boat load that I didn't know already.

I DO have two (count 'em two) QF1a audio filters that I can piggy back in series. I realize that an "audio" approach to electromagnetic QRN may not be the best way to go, but what the hey - worth a shot. The only thing I DON'T like is that they are 120 VAC, even IF I install a chassis ground to L2/G . I really hate to run any receiver  off of  house current if I can avoid it. Oh, BTW, good luck trying to get it to operate on 12 VDC. Autek made it sound so easy,but it was a failed nightmare. I was lucky to get it back to 120VAC function again. Anyhoo,   exploration of the entire issue  has been really fun ,even if it may be the wrong way to go. My noise is variable and per the DX summary above, my QTH is still "usable" but certainly NOT optimal.

I am still going to "soldier on" and build this   medium sized  (bedside) loop anyways, shield or no shield. I have been saving two small spools of 660/46 for a special occasion and may pop that it in for the  air  turns.

The other smaller loop is already partially finished and will be a test bed for active devices, etc.

More to follow,

NQC

143
Equipment / Re: Shielded Loop (Come On , Feel The Noize)
« on: April 09, 2021, 1225 UTC »
Hey All.

Thanks  for the replies.

Ray : A good deal of the info that you presented either newly educated me or helped me recall things that I had read about /experienced, but couldn't recall because they were so long ago.

Many (many)  years ago , I read some info about Common Mode phenomena . I believe it was about noise reduction techniques re wire antennas (not re loops). Differential Mode does not sound as familiar, although in my future  research it might come back  to me (maybe).

FWIW , I am partially of Franco American ancestry and years ago spent some  time in Bitche ,as well as in  Paris. I also enjoyed a number of QSO's with French amateur radio operators back when I was on HF.

Merci.

NJQA: Your LoG sounds cool. I have read some really cool stuff about ON Earth antennas, buried antennas, Earth AS antenna , various types of counterpoise , through  Earth comms systems (especially WW I spark systems), single wire telegraph ,etc, etc, etc.

Some radio operators concentrate more on the "well  ABOVE Earth" aspects of    radio, and less re ON or below it . There is a LOT that can be done  "low". Much of this (IMHO) seems to apply more to below frequencies  10 Mhz ,especially those   below 2 Mhz and really so in to LF/VLF/ULF.

I will check out the W1VLF video.

Thanks.

de NQC

144
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

145
Propagation / Re: Coronal Hole "Plumes" and Magnetic "Song"
« on: April 05, 2021, 1302 UTC »
Hey Skipmuck.

REALLY cool magnetic song.

Kind of in the same category of whistlers, tweeks, dawn chorus ,etc (which I used to mess around with ).

There are STILL new things to be discovered !

de NQC

146
MW Loggings / Re: WQFG689
« on: April 05, 2021, 1222 UTC »
Hey All,

My first post on this web site.

WQGF689 copied on  3/27/21 0145 Z weak to fair in QSB.

Panasonic rcvr on Select -A- Tenna in noisy apt. QTH Boston.

de NQC

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