The acetone in paint or primer evaporates very quickly and so has little chance to permeate the substrate.? I did a search for ABS and Acetone and found some interesting info on using a heated acetone vapor to smooth ABS printed parts where they left the parts in the vapors for an hour or more.? ? From what I saw I think you will be very safe with the paint.?

Rick

Hi Frans, Rick and all who responded:

This is very reassuring and I will probably use an exterior wall paint of matching color. That is what IZ0FYS has done in Italy. His QRZ.com page shows photos.

Frans, if I use a primer spray with <50% acetone, do you think it would soften the ABS plastic?
The black cover is a supporting part of the structure and I would not want to weaken it.

73

Alan DH2AS (G4HEQ)

I think when they said "metal" the meant the elemental form
of the metal, not a compound like TiO. In any event, I
would not worry about the effect of paint, because it will
be negligible compared to ABS pipe, which is a low quality
dielectric.

Rick N6RK

Ooooooo. There's an idea. Teflon tape!

Why not tape it with the required colour?

This may be interesting for LW and VLF/ELF work. I suspect that above 1MHz other effects and non-idealities swamp the common mode rejection ratio of the amplifier.

73, Mike

I think I placed a 1- or 2-page PDF files in the group files section that showed schematics for
simple active antenna amplifiers using the CA3046 transistor array. If not, I'll look around the see
where I put it. It's not on my office computer, so it must be on the laptop.

I found that file in the group files section. The title is:

Active Antenna Amplifiers for Low Voltage Operation RevA.pdf

Although the designs are for low-voltage operation, they can be used for supply voltages up to 12V. For practical purposes, the schematic on the second page is probably the most suitable, and the one on the third page is for demanding situations where even-order distortion from strong signals is a serious problem.


Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE

Active AM Antenna With Twin Coil Ferrite by C. Crane Co.


JLKolb?s antenna links including the KRS AA-1 Active Antenna schematic, antenna preamplfiers, center-tapped loops, and a dual gate FET preselector.


Directional Terminated MW/LW Loop by WellBroook (UK)
K9AY is the Remote Controlled Variable Termination; Provides a Cardioid Reception Pattern with up to 30dB Gain Front-to-Back; Uses Two Delta Loops.


Kiwa - High Performance MW Air-Core Loop Antenna
High Performance MW Air-Core Loop Antenna by KIWA


Palomar Engineers Loop Antennas LW-MW-SW2
Palomar's Loop Antenna gives superb performance on the AM medium-wave broadcast band. The loop rotates and tilts to give deep nulls so you can eliminate local interference. It also allows you to null out a station and listen to another one on the same frequency.


The Quantum loop antennas, now V2.0


Terk AM loop at Amazon.com
Here is a place you can buy yourself a TERK AM loop antenna, even some other stuff that is kind of off topic to talk about. 73


WL1030 by the late Maartenhagg. Plans placed on this website by his friends in his honor.


C Crane Company
They sell the Justice AM Loop Antenna, Select A Tenna, Terk AM 1000


Kiwa Electronics
Kwia makes the best products for you and your radio equipment, and also improves things that needed improvement a long time ago.


Stormwise Ferrite Rods
Get some huge ferrite rods and a converter to go along with its, heck it even comes with project book.


Universal Radio Company
They sell all sorts of loops big and small for LW/MW/SW and VLF also 10 kHz to 15 MHz



ALA-1530
Find the best UK LF/MF antenna here.


AOR
This is the site that sells the AOR loop


Kiwa Electronics
The maker of the air core loop antenna and other useful items that you may want on your wish list.


LF Engineering Company
A group of engineers, who make products for VLF/LF listening even ELF loops!


Select A Tenna by Intensitronics Corp
The maker of the select A tenna, a great AM loop antenna that is a little bigger than the terk
discontinued

Terk Technolegies
The maker of the best sold AM and I use also called the AM-1000 AM loop antenna, there is also technical information on how it works.


Torus Tuner Loop Company
A very specially made loop that is almost as big as a hula hoop
discontinued


GRAHN (Germany) Specialized Loop Antennas for MW and SW Reception Contributed by radiohighfreq
Grahn offers both Ferrite Rod Antennas and Shielded Loop Antennas. Translated from the Gremany Language Webpages here is the "Grahn Specialized Loop Antennas for MW and SW Reception" ULR Address:
Use the Google Translate a web Page Tool to convert these webpages to English.



When considering AM Loop Antennas . . .
- - - It all comes down to Time? & Money?

How much Time? Are you going to be 'using' the Loop Antenna for
DXing or simply for "Better" AM Radio Reception (Sports/Talk Radio
Loop).

How Much Money? Are you willing to spend for a Loop Antenna to get
the kind of better reception you want.

TBL: Time and Money translates to the AM Loop Antenna's Value to You.


The average radio listener (97%), who wants better AM Radio
Reception, can spend $100 or less and get an AM Loop Antenna that
meets their needs.

Here is a brief list of the more common AM Loop Antennas for $100 or
less.

* Twin Coil Ferrite AM Loop Antenna (Active)
- - -

* Torus Tuner 27" Loop Antenna (Passive)
- - - discontinued

* Select-A-Tenna Model #541M (Passive)
- - - discontinued

* Terk AM Advantage Loop Antenna (Passive)
- - -

* RadioShack AM Loop Antanna # 15-1853 (Passive)
- - - Discontinued (Find 'used' on eBay)

* MTM Scientific AM Radio Loop Antenna (Passive)
*
- - - Starter Kit, Deluxe Kit or Finished Antenna!

* * * Home made 'Box' AM Loop Antennas
- Usually 20" to 24" in size
- - Generally a simple Passive antenna
- - - Can be made Active with an add-on amplifier


#1. * Justice AM Loop Antenna (Active)

- - - discontinued

#2. * Torus Tuner 27" Loop Antenna (Passive)

- - - website gone

#3. * Select-A-Tenna Model #541M (Passive)

- - - website gone

#4. * Terk AM Advantage Loop Antenna (Passive)

- - -

#5. * RadioShack AM Loop Antanna # 15-1853 (Passive)

- - - Discontinued (Find 'used' on eBay)

* MTM Scientific AM Radio Loop Antenna (Passive)
*
- - - Starter Kit, Deluxe Kit or Finished Antenna!

* * * Home made 'Box' AM Loop Antennas
- Usually 20" to 24" in size
- - Generally a simple Passive antenna
- - - Can be made Active with an add-on amplifier


NOTE: Beyond $100 in the $200 to $400 range are the

#1.a. Kiwa MW Air Loop Antenna

#1.b. Quantum Loop Antennas

. . . #3. Palomar Loop Antenna


Basic Wire Back Yard Loop Antennas
Full-wave loops are very popular antennas. They are especially useful on 80 and 40 meters where they perform well at modest heights. These are closed loops that are one full wavelength long. Horizontal loops may be fed at any convenient spot. For best performance, make your horizontal loop into a square, especially if it is to be used on several bands.


K9AY: How to Build the K9AY Loop Receiving Antenna
AY Technologies Antennas by K9AY. Excellent Antenna for Medium Wave Frequency DXing.


Six Foot Square by Six Turn Loop Antenna
New Mid-Size Loop Antenna by Graham Maynard with Matching Balanced Amplifier: Frequency Range 50KHz - 5000KHz.


Ten Foot Receiveing Loop for Low-Frequency DXing
A Page out of VE7SL's Note Book. This 10 Ft. Air-Core Receiving Loop was originally designed and constructed for NDB DXing and now is used for LOWFER DX work.



Dave's HomeMade Loop Antennas
This is the loop antenna my dad built in 1958. Although I was only 8 years old at the time, I knew what this was for and how it worked. WebSite/Pages produced by Dave Schmarder Page Contributed by radiohighfreq


4 Foot Box loop antenna
Heres a 4 foot loop project by Bruce


ATL-3 Loop Antenna by Graham Maynard (UK)
Loop & Amp Project: ATL-3 Loop Windings are in the Shape of a Five 26" Sided Spiral


Alt-Azimuth Wooden "HOOP LOOP" Antenna by Linus
The Great Pumpkin" Speaks on "How To Make" a Loop Antenna from a Wooden Embroidery Hoop. Read the Exciting Saga of his journey in to the Kingdom of Hooppy-Looppy-Dom presented by RadioIntel.Com.


DXers Tool Box - DIY - Tuned Loop Antenna
The DXers Tool Box "How To Build" a Tuned Loop Antenna = How can you vastly improve your Medium Wave reception? The antenna consists of an LC (tuning) circuit formed by the air-core loop and a tuning capacitor.


Embrodary Loops
While these loop are for crafts, they can be a craft of art for improved AM radio reception!


Hard Core DXing
Here's what nordic dx has to offer in their discription of loops in this website


K5DKZ - Three Foot Box Loop Antenna Kit
Complete Parts and Plans for a 3 Ft Box Loop Antenna "Kit" ~$85+SH


KIT -by- MTM Scientific, Inc. -for- AM Radio DX Loop Antenna
KIT =//= Designed to Build an AM/MW Radio DX Loop Antenna =//= Offered by MTM Scientific =//= Deluxe Loop Antenna Kit: Includes ALL the Hardware for Building this AM/MW Radio DX Loop Antenna.


Long LoopStick Antenna for MW DXing
Wound on a Three (3) Foot Length of PVC pipe, the "Long LoopStick Antenna" was an experiment to try to improve AM radio reception without using a long wire or ground.


TL Loop Receiving Antenna 10 KHz - 30 MHz
The principle of operation is that an rf voltage appears across the terminals of a loop when it is placed in an electromagnetic field. The voltage is proportional to frequency for a given field strength and so at Very Low Frequencies the voltage is very small and requires greater amplification but it is not quite as simple as that. The new TL Loop uses a unique feedback system to optimise the amplification/noise factor over a much wider range than has been possible hitherto.



W2BRI Xmit Loops Contributed by n3hkn
Ham Radio xmitting loops. Detailed plans and reports from Hams experiences. Typical cost is $50 for pipe, capacitor, motor.


"AM Loop Antenna Calculator" - by Bruce Carter
Here is a Great Tool for those Loop Antenna => "What Ifs...."


"Loop Antennas 101" Read This First
Minnesota DX Club's Loop Antenna's web page that is a 'Must Read' =Says It All= A Starting Point Class 101- - - TOPICS: Principles of the Loop Antenna - What is a Loop and Why Use It - Construction Principles - What Can I Use a Loop For - Loops Another Look - Pictures of Home Built PVC loops - Loop Links


* NEW => 2002 AM Loop Antenna Construction "Tips" by Bruce Carter
Introduction / Why Another Loop Antenna Page? / Mathematics of Rectangular Loop Antennas / Construction Articles / Loop Antenna (and Related) Links


Loop Antennas at Hard Core DX
TABLE: Number of Turns -v- Size of Loop in the Middle of this webpage.


Loops and Rods =&= The Ferrite Rod Antenna
Theory / Formulas / Drawings = The use of a small Magnetic Loop as an antenna. The ferrite has the effect of intensifying the magnetic field inside the loop.


Modify the common AM Radio Loop Antenna
Hard-Core DX & Nordic DX = Topics: Install Larger Ferrite Rod - Fix External Antenna -Add a Long Wire - Or a Loop - Construct it - Connect it - Add an Amplifier. Presented by Bruce Carter


Sensitivity of Multi Turn Receiving Loops
LWCA - Multi turn wire loops are often used as low frequency receiving antennas. Basic electromagnetic theory is developed here as it relates to electrically small multi-turn loops at low frequencies. - Presented by William E. Payne, N4YWK


Using the Small Loop Antenna by Joe Carr
DXing.Com presents Joe Carr's Radio Tech Notes: Eight Page PDF Document provided by Universal-Radio.Com



How to Get Better AM Radio Reception
Features Loop Antennas and much more. The Antenna is 90% of Your Radio. Still Need More Signal? Try a Better Antenna.


Introduction to Broadcast Band AM/BCB/MW DXing
The International Radio Club of America (IRCA) WebPages



** Radio-Antenna-PRO ** H.Hertz-Forum
Remember you may need some Russian Text software for this groupThe international forum for radioengineers, scientists and hams. All about radioelectronics, radiocommunications, radiophysics, electrodynamics. About 250 members from 20 countries. In Russian language. Very active. Lot of interesting researches and discussions.



Radio DXing with The Interference Problem
This is great for that annoying problem you have with your loop antenna, and you may think its the loop, think again it could be that messed up street light, next doors dimmer switch, and other something else you can't probably solve with just a loop antenna.



"3805er" 80-Meter balanced coax loop
Small shielded rx only loop for 80 meters


Magnetic Loop Antennas Receiving - by W8JI
This WebPage's Topic Are: - Small Receiving Loops - Loop Antenna Fields - Dipole Antenna Fields - Radiation - Loop Shielding and Balance - by W8JI


Radiation and Fields (Magnetic Loop Antennas) - by W8JI
This WebPage's Topic Are: - Electric Field - Magnetic Field - ElectroMagnetic Field - Near the Antenna - Losses - Near Field - Fresnel Zone - Farfield - Summary - by W8JI


Shielded-Loop Receiving Antenna by N5FC
Shielded-Loop antennas have some nice properties that make them desirable as portable receiving antennas.


Antique Electronic Supply
A sorts of older variable tuning capacitors for your loop antenna that needs one bad.


Fair Radio Sales
A wide variety of electronic components, radios, and variable capacitors for your loop antenna


Ocean State Electronics
Rhode Island's best selection for a wide variety of the best tuning capacitors for reasonable price, tell them that electronicdx (Adam Ebel) sent you.


The Crystal Set Society
Here are some capacitor available from a club that devotes to Crystal Set Radio


The Surplus Sales of Nebraska
This surplus store based in the state of Nebraska, has the one you might need, but they have minumim order policy



Dan Small Parts and Kits
Dan's wide selection from Canada.



American Science and Surplus
A big spool of wire here just about for AM


DigiKey.com
For ribbon cable and other sorts of wire.


Femco Magnet Wire
Femco Magnet Wire is a joint venture company that has been supplying round insulated copper magnet (winding) wire to the transplant market since 1988.


Litz-Wire,com
Welcome to Litz-Wire.com!


MCM electronics
They do sell wire and magnet wire here


MWS Industries
A place for all sorts of wire for business and industry


Magnet Wire from Radio Shack
This is what I use often


Mouser Electronics
Mouser has the biggest spools here for a great price, that makes sense


Ocean State Electronics
magnet wire at a good price


WIRE "Flex-Weave" Antenna Wire
"Flex-Weave" is a hybrid aerial wire that consists of 168 strands of woven #36 solid copper wires that provide high strength and extreme flexibility. The most popular version of "Flex-Weave" is the 'equivalent' of #14 AWG wire size. It can be 'used' for unsupported spans up to 200 ft (100-150 ft in areas with high ice and wind loading).


WIRE "QuietFlex" Antenna Wire by Antennas & More: Insulated, Strong, Flexible and Durable
"QuietFlex" Antenna Wire by Antennas & More: "QuietFlex" #14 AWG Wire has more than 41 Strands tightly twisted together under its Flexible Insulation making it both Strong, Flexible and Durable.


Scanning, Ham Radio and Public Safety Resources
- Links to the various webpages with resources for the Ham Radio Operator and Scanning Enthusiast. Resources such as; Monitoring Police and Fire Communications, What Antennas to use, Secret Scanner Frequencies, Radio Programming Software, Radio Mods and Operating Tips, Professional resources for Public Safety Management, Guidance and Self-Help.


Amidon Ferrite rods, bars, plates, and tubes.


Bytemark Ferrite rods, bars, plates, and tubes.

If you have a link relevant to the group, please post it in the Links section. If you just put it in a message, it will get lost in the shuffle after a few days. The coverage of the list is pretty broad.

All members can upload Links, Files, and Photos.

A few guidelines:

Try to place them in the proper folder, if it exists. If not, you can either just put it in the root folder and eventually I'll move it into the proper place, or create a folder.

When creating a folder or uploading a file or photo, please don't use spaces or punctuation. You can either use caps for the first letter of each word, or use underscore as a space.

Like this: "4x8Loop" or "4x8_loop" or "Steves_4x8_Loop"

Not like this: "Steve's 4 x 8 Loop." That goes for Folder names and File names.

A special note about the Photos section: Please crop in to the important parts. For photos, JPG saves smaller and looks better, for line drawings GIF is smaller and looks better. Please do not use TIFF/TIF or BMP files, the file size is way too big and I may delete without notice.

Feel free to ask if you need help figuring out how to crop and resample. Irfanview is a fairly easy to use program that loads just about any file, you can crop and resample from there:

Or for more complex stuff, another free program is GIMP:

Attachments are now allowed, but please use judiciously. Rather than going out with the messages, they will be stored on the list but you'll get a link with the message.

A last note: if you see something in any folder or in the messages that looks like spam or simply inappropriate, don't post on the list- email me directly and tell me about it and I'll take care of it with a minimum of fuss.
loopantennas-owner@...

Thanks,
Steve Greenfield

开云体育

On 4/30/2014 5:54 PM, Richard (Rick) Karlquist wrote:

?

On 4/30/2014 7:39 AM, n3ikq@... wrote:

> Put another way, Does the mechanical complexity of a remotely tuned
> variable capacitor provide any advantages over varicap diodes with all

One other problem with varactors is testing. The loop design
I published in the National Contest Journal cannot be tested
with the MFJ-259 impedance meter (and probably similar units)
because the drive level is too high. I only recently discovered
this. I did all the development work originally with an
HP 4815 vector impedance meter. I also found that if I
used an Agilent E5071C VNA, I had to reduce the drive level
below the default level of the instrument.

Rick N6RK

_

When I measured the batch I got I built a buffered VCO with the L.O. coil from an old MW radio using a socket for the varactors to test the frequency output at 12 discrete voltages using a 12 position switch and resistors.

Fed the output to my scope and the output from the scope to a cheap frequency counter. A bit of Math (and a spreadsheet) gave me the cap. values at different voltages and monitoring the waveform on the scope showed if they were noisy or unstable. Neither the scope or the counter had to be NBS traceable or anything since I was comparing apples to apples so to speak and in circuit stray capacitance would be more than the measurement error anyway.

Still have the test jig around here somewhere....

Tim Hills
Sioux Falls, SD

On 4/30/2014 7:39 AM, n3ikq@... wrote:

Put another way, Does the mechanical complexity of a remotely tuned
variable capacitor provide any advantages over varicap diodes with all

One other problem with varactors is testing. The loop design
I published in the National Contest Journal cannot be tested
with the MFJ-259 impedance meter (and probably similar units)
because the drive level is too high. I only recently discovered
this. I did all the development work originally with an
HP 4815 vector impedance meter. I also found that if I
used an Agilent E5071C VNA, I had to reduce the drive level
below the default level of the instrument.

Rick N6RK

开云体育

I've been using varactors for MW and LW loops for years. There are a couple of things to be careful of.

When using a back to back configuration I've found it best to match them as closely as possible. An imbalance increases the chances of IMD and other problems.

The lower the signal level across the varactors the better. I use set of 4 pairs (8 total) MVAM109s to tune a ferrite loop and have used as many as 10 pairs (20 total) for a LW air core. The higher capacitance allows for fewer windings and lower AC voltage across the junctions and matching is easier if 4 parallel varactors are matched to 4 others. I got lucky and bought 300 of them for next to nothing, rejected lot with 50 of them being defective but I still see those or similar in bulk on Ebay from time to time.

I also use a second center tapped pickup loop with a balanced MOSFET preamp feeding a balanced line to the receiver. Even with 3 BC stations close enough to hear on the toaster I don't get any noticeable intermod.

I prefer varactors mostly because I stick to the KISS principle as much as possible. A well regulated reference voltage, a 10 turn pot, a single op-amp, a few resistors and caps and one wire is all that's needed for control.

I've heard of people having problems with varying ambient conditions. The attic above the garage where the loop was mounted goes from -30F in winter to over 140F in the summer. The antenna is "noisier" the hotter it gets but I can say the same for any MW antenna since atmospheric noise in this region is very high from April to October so it may be junction noise or it may just be background/thunderstorms. Probably a combination.

HTH
Tim Hills
Sioux Falls, SD

Yes, that's the circuit.
. I thought the point was to
have such a high impedance that the loop/inductor was not effected by the
directly attached preamp. Another interesting design is from the late
Ralph Burhans. I bought and used his preamp way back in the 80's and lost
it. I was happy to find the design again. However, it is not a tuned design
and I'm not quite sure if I can just slap a tank circuit on the transformer
input.

I'll look at that later when I have a WiFi connection. The loop antenna is best viewd as being a current source with a series inductance and a low series resistance. When seen that way, series tuning with a low input impedance amplifier becomes obvious.

I think I placed a 1- or 2-page PDF files in the group files section that showed schematics for simple active antenna amplifiers using the CA3046 transistor array. If not, I'll look around the see where I put it. It's not on my office computer, so it must be on the laptop.


Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE

Yes, that's the circuit. . I thought the point was to have such a high impedance that the loop/inductor was not effected by the directly attached preamp. Another interesting design is from the late Ralph Burhans. I bought and used his preamp way back in the 80's and lost it. I was happy to find the design again. However, it is not a tuned design and I'm not quite sure if I can just slap a tank circuit on the transformer input.

Wow answers from the living legends themselves! I have a few of your documents in my files that I have
been educating myself from! The balanced (differential) preamp I am gathering parts for is from a paper
by Lyle Koehler.

Is that the one with the balanced MPF102 input stage and a balanced 2N2907 output stage? I have reservations about that approach as the low impedance of a loop pretty much dictates a low input impedance amplifier with series tuning. His design is more appropriate for use with a short dipole, which can be a pretty good small antenna. But, his amplifier is fairly simple.


Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE

Wow answers from the living legends themselves! I have a few of your documents in my files that I have been educating myself from! The balanced (differential) preamp I am gathering parts for is from a paper by Lyle Koehler. It seems to be a variation on a common design as it appears to be used by at least two of the three builders of commercial loopstick antennas. I am guessing the balanced, center tapped loop design allows the loop (or interchangeable coils) to be grounded thereby protecting the FETs from ESD. Anyway thanks for the great feedback. I was guessing that the varicaps had some sort of Achilles heel that keeps the antenna builders looking for good old fashioned variable caps. My remote variable capacitor design is nothing earth shattering but I have made it to use standard cat5 cable and cheap eBay stepper motors from China. I use the three left over cat5 wires for positional feedback from a pot attached to the cap. All 8 wires get used and cat5 cables are everywhere so no custom cables need to be built.