Hi Ed
Disagree on a few points there.
But best tubing I have found is air con tubing or if you can get 2 inch heliax coax..but if air con Not china made!
Ali at best has twice R of copper. More losses.
And getting pure ali tubing/foil is nigh on impossible. Plus foil is in my opinion a no no.( especially if on low bands)
Also have to be careful with copper..ie don¡¯t use copper water pipe as that is very impure..( why its cheap.)
Plus of course no joins in tubing except at vac cap ( if join¡¯s needed then silver brazed.)
Thats of course if you after a GOOD performance mag loop and not a portable one..
Simon g0zen
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On Sat, 17 Sep 2022 at 15:14, Richard \(Rick\) Karlquist \(N6RK\) < richard@...> wrote: Which group is discussing Q meters?
The main thread is?
However, there are a few other threads that are related, but sufficiently different to warrant their own thread.
Dave (owner of the above group) -- Dr. David Kirkby, Kirkby Microwave Ltd, drkirkby@...Telephone 01621-680100./ +44 1621 680100 Registered in England & Wales, company number 08914892. Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United Kingdom
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Design your loop with 66pacific small transmitting loop calculator () or similar program. Build your loop from copper tubing/pipe, aluminum tubing/pipe or pvc pipe covered with aluminum foil tape...yes...aluminum foil tape. For the Aluminum Foil Tape Covered Loop see, "Optimum Magnetic Loop Antenna -John Portune-" on YouTube. Yes it's a square loop and it works. Many first US contacts were to South Afirca and Australia/New Zealand.? Use a VNA for tuning, matching etc. for all the you really need to know. Enjoy your new loop and beware of the high RF voltages. And "now you have the rest of the story".
On Sat, Sep 17, 2022, 10:15 AM Richard \(Rick\) Karlquist \(N6RK\) < richard@...> wrote: Which group is discussing Q meters?
I assume you are talking about transmitting loops.
Litz wire in general, doesn't do much for frequencies
above 1 MHz or so.? The only ham band where it could
do anything useful would be 160 meters.? For 80 and up,
it is a complete waste of money.
The other thing is that that when litz wire is used,
it is for building conventional air core solenoidal
inductors, where the physical size of the wire matters.? It
doesn't matter for a loop antenna, so it is much simpler
to just use larger wire or tubing than litz wire.
For a loop antenna, it is extremely simple to calculate
the RF resistance of the loop conductor and the inductance
of the loop.? From those two parameters, the unloaded Q
can be determined.
The RF resistance of copper wire/tubing in milliohms per
foot is given by the square root of frequency (in MHz)
divided by the diameter of the wire in inches.
It is also extremely easy to measure the loaded Q of a
compete loop antenna (including the resonating capacitor)
with any network analyzer.? No need for a Q meter.? HP
4342 Q meters are extremely rare and expensive.
Spending a lot of money on large copper pipes for the TX
loop results in high Q, which causes very narrow bandwidth,
and limited power handling.? Much better to make the loop
larger and just use wire for the conductor.
Rick N6RK
On 9/16/2022 10:38 AM, Steven Greenfield AE7HD via wrote:
> Watching the discussion about Q meters in another group.
>
> I see people here sometimes building loops with copper pipe or litz wire
> to reduce losses. What about actually measuring Q?
>
> I have some ideas that I may post after testing them out a bit, first.
>
> I have a 220pF silver plated var on a 100:1 reduction in an old
> frequency meter for the project.
>
> --
> Steve Greenfield AE7HD
>
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Locked
Re: Wellbrook loop fails with heat
I lived in Arizona before moving to Oregon and have had 3 modules fail in about 15 years, probably from heat. Andy has been kind enough to replace them when I asked about the failure.
I cover the bottom of my loops with foam pipe insulation. I have seen it in grey instead of black on occasion. That seems to work for wet, heat and 'birds' if you know what I mean!
Dave Aichelman? ? ?N7NZH? ? ?Grants Pass, Oregon
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Locked
Re: Wellbrook loop fails with heat
Cover them with shiny stuff...ya think... trust me...those of us who were born, raised and live in Florida (I am an engineer whose family has been in Florida for almost 100 years and I for 80 of'em) have thought of and used shiny stuff many times in the past. However when your electronics are dosed by the Florida sun, day after day after day, the shiny stuff only goes so far. I have used heat transferring adhesives and compounds when attaching heat sinks to potted electronics and then use a small cooling fan to maximize the removal of heat. With the additional heat generated by the electronic components themselves, the shiny stuff compounds the problem by retaining the heat just as the resin potting surrounding the electronics does. There epoxy potting products are designed to handle high heat that won't crack and tear at your electronics and will keep moisture out as well. We use epoxy resins every day in Florida that are formulated to handle our environment. I was raised in and around the marine industry and was there when we experienced the learning curve when transitioning from wood to fiberglass in boats. I have worked with resins in the marine, automotive and aviation environments (both structural and electronics) most of my life. I am familiar with the adaptations and uses of epoxy resins.These heat/uv resistant resins may not be an "on the shelf" item in many European countries. It's still a design team problem with a buyer be informed note attached. ?
On Sat, Sep 17, 2022, 9:55 AM Everett N4CY via <everettsharp= [email protected]> wrote:
Guys,
?
The best thing to do is protect them from the direct sun. You could cover the head amp with a shinny aluminium cover. THINK OUTSIDE THE BOX.
?
Everett N4CY
In a message dated 9/17/2022 8:43:29 AM Central Standard Time, ed650p@... writes:
?
I agree, the Florida, Arizona heat problems destroy most outside use electronics. This is especially true of products designed and used in European countries. They do not take into consideration that in today's global market (think Amazon and Ebay), products designed in one market will be sold and used all over the world. As buyers, we need to take this into consideration as well. If it works in Europe's cold harsh climates, doesn't mean it was designed for Florida's heat, rain and coastal salt laden air.
These things need to be taken into consideration by designers and buyers alike.?
That being said we own a plethora of DC cooling fans for use on our various electronics here in Florida.
I am on my third Wellbrook replacement loop head. It appears that the potted resin is not only keeping water out (amongst other things) but seriously keeping heat in. The heat buildup in Florida is upside of 100F.
When operational, the resin heats with the current flow through the ferrite (like an immersion heater). Due to the temperature expansion differential between the components (esp ferrite) and the resin, mechanical forces appear to be cracking the ferrite and the tiny wiring transformers inside the head. So if your loop head has failed similarly, you will notice zero signal suddenly as the RF comes to a dead halt. Confirm by checking the resistance across the the loop leads which will be >1k.
I can only appeal to the manufacturer to cease the process of potting or offer a lifetime replacement guarantee.
|
Hi
¡°Spending a lot of money on large copper pipes for the TX
loop results in high Q, which causes very narrow bandwidth,
and limited power handling. Much better to make the loop
larger and just use wire for the conductor.¡±
Question..Where did you get that idea from?? Unless you talking about a full L loop for whatever frequency.ie 160 circumference for 160m??
As my large dia coper tubed tx mag loop with vac cap holds 1.5kw..( 160m)
No hope with wire as eff will be zero..
Asking as maybe mis understanding your reasoning.
Simon g0zen
|
Which group is discussing Q meters?
I assume you are talking about transmitting loops.
Litz wire in general, doesn't do much for frequencies
above 1 MHz or so. The only ham band where it could
do anything useful would be 160 meters. For 80 and up,
it is a complete waste of money.
The other thing is that that when litz wire is used,
it is for building conventional air core solenoidal
inductors, where the physical size of the wire matters. It
doesn't matter for a loop antenna, so it is much simpler
to just use larger wire or tubing than litz wire.
For a loop antenna, it is extremely simple to calculate
the RF resistance of the loop conductor and the inductance
of the loop. From those two parameters, the unloaded Q
can be determined.
The RF resistance of copper wire/tubing in milliohms per
foot is given by the square root of frequency (in MHz)
divided by the diameter of the wire in inches.
It is also extremely easy to measure the loaded Q of a
compete loop antenna (including the resonating capacitor)
with any network analyzer. No need for a Q meter. HP
4342 Q meters are extremely rare and expensive.
Spending a lot of money on large copper pipes for the TX
loop results in high Q, which causes very narrow bandwidth,
and limited power handling. Much better to make the loop
larger and just use wire for the conductor.
Rick N6RK
toggle quoted message
Show quoted text
On 9/16/2022 10:38 AM, Steven Greenfield AE7HD via groups.io wrote: Watching the discussion about Q meters in another group.
I see people here sometimes building loops with copper pipe or litz wire to reduce losses. What about actually measuring Q?
I have some ideas that I may post after testing them out a bit, first.
I have a 220pF silver plated var on a 100:1 reduction in an old frequency meter for the project.
--
Steve Greenfield AE7HD
|
Locked
Re: Wellbrook loop fails with heat
Guys,
?
The best thing to do is protect them from the direct sun. You could cover the head amp with a shinny aluminium cover. THINK OUTSIDE THE BOX.
?
Everett N4CY
In a message dated 9/17/2022 8:43:29 AM Central Standard Time, ed650p@... writes:
?
I agree, the Florida, Arizona heat problems destroy most outside use electronics. This is especially true of products designed and used in European countries. They do not take into consideration that in today's global market (think Amazon and Ebay), products designed in one market will be sold and used all over the world. As buyers, we need to take this into consideration as well. If it works in Europe's cold harsh climates, doesn't mean it was designed for Florida's heat, rain and coastal salt laden air.
These things need to be taken into consideration by designers and buyers alike.?
That being said we own a plethora of DC cooling fans for use on our various electronics here in Florida.
I am on my third Wellbrook replacement loop head. It appears that the potted resin is not only keeping water out (amongst other things) but seriously keeping heat in. The heat buildup in Florida is upside of 100F.
When operational, the resin heats with the current flow through the ferrite (like an immersion heater). Due to the temperature expansion differential between the components (esp ferrite) and the resin, mechanical forces appear to be cracking the ferrite and the tiny wiring transformers inside the head. So if your loop head has failed similarly, you will notice zero signal suddenly as the RF comes to a dead halt. Confirm by checking the resistance across the the loop leads which will be >1k.
I can only appeal to the manufacturer to cease the process of potting or offer a lifetime replacement guarantee.
|
Locked
Re: Wellbrook loop fails with heat
I agree, the Florida, Arizona heat problems destroy most outside use electronics. This is especially true of products designed and used in European countries. They do not take into consideration that in today's global market (think Amazon and Ebay), products designed in one market will be sold and used all over the world. As buyers, we need to take this into consideration as well. If it works in Europe's cold harsh climates, doesn't mean it was designed for Florida's heat, rain and coastal salt laden air. These things need to be taken into consideration by designers and buyers alike.? That being said we own a plethora of DC cooling fans for use on our various electronics here in Florida.
I am on my third Wellbrook replacement loop head. It appears that the potted resin is not only keeping water out (amongst other things) but seriously keeping heat in. The heat buildup in Florida is upside of 100F.
When operational, the resin heats with the current flow through the ferrite (like an immersion heater). Due to the temperature expansion differential between the components (esp ferrite) and the resin, mechanical forces appear to be cracking the ferrite and the tiny wiring transformers inside the head. So if your loop head has failed similarly, you will notice zero signal suddenly as the RF comes to a dead halt. Confirm by checking the resistance across the the loop leads which will be >1k.
I can only appeal to the manufacturer to cease the process of potting or offer a lifetime replacement guarantee.
|
Locked
Wellbrook loop fails with heat
I am on my third Wellbrook replacement loop head. It appears that the potted resin is not only keeping water out (amongst other things) but seriously keeping heat in. The heat buildup in Florida is upside of 100F.
When operational, the resin heats with the current flow through the ferrite (like an immersion heater). Due to the temperature expansion differential between the components (esp ferrite) and the resin, mechanical forces appear to be cracking the ferrite and the tiny wiring transformers inside the head. So if your loop head has failed similarly, you will notice zero signal suddenly as the RF comes to a dead halt. Confirm by checking the resistance across the the loop leads which will be >1k.
I can only appeal to the manufacturer to cease the process of potting or offer a lifetime replacement guarantee.
|
Locked
Re: Chinese try to clone Wellbrook loop
Dear Jinze and other members:?
Please,have a look at??for my attempt for a open source version of the LZ1AQ amp.
73, Andre, pa3ajr
|
Watching the discussion about Q meters in another group.
I see people here sometimes building loops with copper pipe or litz wire to reduce losses. What about actually measuring Q?
I have some ideas that I may post after testing them out a bit, first.
I have a 220pF silver plated var on a 100:1 reduction in an old frequency meter for the project.
--
Steve Greenfield AE7HD
|
Locked
Re: Chinese try to clone Wellbrook loop
?
This man is a liar, the antenna he sells on the second-hand market in China is a joke, many Chinese hams are also deceived, there is a false propaganda appearance,
his name is "Goku Antenna", I want to like the antenna Lovers should try their best to make excellent LZ1AQ open source designs by themselves
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Hi Jeff,
thanks for the prompt replay and picture. I am sure many magloops lovers will get RF excited...hi
73
Gian I7SWX
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? HIMARS Image in Ukraine. ? The HIMARS built for other countries appear to have 2 verticals on either side of the transport vehicle. ? --jeff
|
Hi, is it possible to have a picture of an HIMARS transport with the loop antenna?
Thanks and 73
Gian, I7SWX
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Locked
Re: Half LZ1AQ Transistor Noise Output at LF and Norton 10 MHz gain and NF comments
This Website might be of interest for some of you (in German, use translator):
Richie's hobby is to open transistors and ICs and take perfect macro photos and explain the silicon chips inside.? Amazing.
Here his 2222 Pictures:
Regards
Fred
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Locked
Re: Half LZ1AQ Transistor Noise Output at LF and Norton 10 MHz gain and NF comments
Thank you Steve, for this valuable Information. It might well be, that both dies are from the same manufacturing plant. I like the PZT2222A and PZT2907A for their robustness and use them in active antennas as output buffer in push-pull configuration. In the spcific case of an LZ1AQ amplifier i wonder if it would make sense, to use a low noise transistor in the noise determining first amplifier stage and the more robust 2222A as output driver.
Regards
Fred
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A small loop - <10% circumference of a full wavelength at the highest frequency of interest - exhibits the nulls in both directions perpendicular to the plane containing the loop.? So, laid horizontally on the soil surface, the loop will null NVIS signals.
Dave - W?LEV?
Another silly question, if I lay a single turn loop horizontal to the ground will it receive NVIS?
Yes, the donut pattern will be on its side and receive high angle waves.? mount above the ground,?
--
Jim, KA6TPR
-- Dave - W?LEV
Just Let Darwin Work
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Another silly question, if I lay a single turn loop horizontal to the ground will it receive NVIS?
Yes, the donut pattern will be on its side and receive high angle waves.? mount above the ground,?
--
Jim, KA6TPR
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Everett N4CY
PA3AJR
Steven Greenfield AE7HD
Giancarlo - I7SWX
Starsekr