Radmor 32812/1 Clone: Aluminum vs Steel Tube, Dimensions & Wall Thickness Importance

Partly because of the lack of availability, partly because of the desire to play, I decided to make a clone of the Radmor 32812/1 antenna.

There is a nice description on the forum: https://www.elektroda.pl/rtvforum/topic3269073.html

Most of the items are easy to get, besides:

Quote:

aluminum tube 430 mm long and 42 mm outside diameter - wall thickness 2 mm

The only pipe with exactly the dimensions that I found is steel. And now the question is how important is the criticality of the dimensions of this element? Give a steel pipe with exactly the same dimensions or aluminum, but with an outer diameter of 40mm and a wall thickness of 1.5mm - the same as for the second antenna element?

http://www.investa.pl/oferta/aluminium_rury.html
It is "made to order" and 40 x 2 is in stock. Maybe it's worth asking about the conditions.
edit is here too.
http://ktinox.pl/aluminium/rury/

Thanks, I sent your inquiry. The topic remains open - what is the significance of these elements in terms of the theory of antenna construction.

I answered HERE with the auxiliary numbers, but immediately deleted, misread your numbers.
I don't have any personal attitude to Radmor's "clubs". I assume that many dream about them, many, already in their hands, report problems.
Do you motivate yourself? Do you treat her as cult too?

If you have pipes, I can help you dimension J in the physical system pipe in pipe in pipe. Lemm AT-78
The official appearance is this:
https://www.merx.pl/198-ante.html

Has an idea that makes tuning easy, after disconnection there is a reed-coupler inside
https://obrazki.elektroda.pl/7572410300_1466180051_thumb.jpg

I wonder how you will say.

I decided not to think twice. I went and bought a 40x1.5 pipe and I gave it to both elements. The only thing missing is a coil, a disk for the socket and some invention to center the radiator.
DSC00737 (...edium).JPG (70.01 kB)You must be logged in to download this attachment.
DSC00735 (...edium).JPG (131.91 kB)You must be logged in to download this attachment.

The cost of what in the pictures is about PLN 50 including an external PVC pipe that is also waiting. Missing items will not exceed PLN 10, but I have to look for what to figure out for this disc, because in the local store the bars only sell in 4 m sections. It is 3.92m too much.

As for the antenna itself - are you able to point another antenna on VHF with such SWR in such a band? Honestly, I've been looking for a long time. J-ka on the 2m amateur band in the 160MHz band has SWR over 2. So under 174MHz it will probably be deaf. Probably even the usual GP1 / 4 is not so broadband - but unfortunately I could not find a graph showing its SWR anywhere in the entire range of 144-174MHz. So much theory. And in practice - the antenna is highly praised by users. I even met with many opinions that it is better than Discone.

Sumar wrote:

.... So many theories. And in practice - the antenna is highly praised by users. I even met with many opinions that it is better than Discone.

Discone has a known assumption: sacrifice everything for the band, the efficiency is less than that of a bare 1/4 "speaker".
It is not known why the 130-175MHz listening antenna most often bought, which is quite narrow.
I think it's easy to break through its effectiveness in any narrower band.

Before changing the disk, I intensively calculated such open-sleeve antenna systems in Maaan Gal:
http://www.eham.net/articles/8808
http://www.qsl.net/dk7zb/Duoband/dipolduoband.htm
when the optimizer was released, it hit very interesting band parameters. I will come back to this

Sumar wrote:

Most of the items are easy to get, besides:

Quote:

aluminum tube 430 mm long and 42 mm outside diameter - wall thickness 2 mm

The only pipe with exactly the dimensions that I found is steel. And now the question is how important is the criticality of the dimensions of this element? Give a steel pipe with exactly the same dimensions or aluminum, but with an outer diameter of 40mm and a wall thickness of 1.5mm - the same as for the second antenna element?

The use of a tube with a 2mm wall in the bottom part is dictated by the fact that this tube is also the supporting part of this antenna. Must be more resistant to dents etc.

There will be no aluminum disc. On the UC-1 socket I put two metal strips (the remnant of the chimney clamp attachment) crosswise and refined with a grinder.

It would be nice to check it now on some professional analyzer, but I do not have access to such things.

From the initial measurements of reception, the signal in SDR Sharp is 5-7dB stronger than from the classic half-wave dipole on the roof (the stick is in the room for now).

As I mentioned before, the cost of the whole closed at PLN 60.

Good work, it's a shame you don't have an aluminum disc, but it can be anyway. What are these brown stabilizers for?

The usual copper washers that suited my trash collection the most, because I couldn't drill these 4 holes perfectly and I had to match them with a file, which made them a bit too big.

I think that this fastening of the socket is enough for now. In the end I tried to copy everything except the famous long-term durability.

And finally I checked the antenna outside, at the same height above ground level as my previous classic dipole. The results are:

Local 145.650 MHz drive:
- dipole -18dB
- baton -18dB

Local 145.7625 MHz drive:
- -15dB dipole
- club -3dB

Local base at 172 MHz:
- dipole -20dB
- club -6dB

Local drive 439.200 MHz:
- dipole -20dB
- club -16dB

Generally you can see a big improvement, except for one inverter at 145.650 MHz - its the same way. Interesting...

Complete antenna exposed for testing outside:
pała-st...jpg (96.77 kB)You must be logged in to download this attachment.

To sum up the topic - it is possible to build a cheap clone of this antenna. However, the measurement of the resulting structure remains the biggest problem. If I manage to do it someday, I will definitely put the results here.

Hello, I also decided to build a Radmor stick, photos of my performance, best regards

Very nice and refined workmanship! Will you write a few words about the aluminum disc, the plastic connecting the two pipes and the red radiator stabilizers?

The uc1 socket disk is made of stainless steel, while the insulator is made of polyamide and the spacers are made of rubber The antenna has been powder coated so as not to use a PVC pipe

Great! Did you take any measurements?

Yes, I took one piece apart and took measurements

Sorry, I should clarify right away - I meant SWR measurements, etc. I wonder if it was good right after assembly or if you had to tune - if so what - stretching the coil or the length of the radiator. I've never tuned my own, because I don't even have the simplest meter for this band.

This stick is made for the 158MHz band and tuning took place on the extension of the upper aluminum tube.

Hello
In the link given in the first post, i.e. https://www.elektroda.pl/rtvforum/topic3269073.html

There is a description of the antenna but I do not agree

1 why the dimension of the bottom pipe is in the description 430mm? For version 1, the tables do not give other dimensions

2 Total antenna length:
Graph Length
[Mm]
1 1320
2 11790

in the table for length 2 is 11790 mm, which gives 11 meters interesting?

Not interesting, just probably clicked the author 2x in 1.

In this case it is possible that yes but with these pipes it is already interesting in table 316 in description 430

Looking at the dimensions for previous versions I would roast at 430, or wrote to the author of the description - the mail is in pdf.

>>17648671
Hello. Question about painting the antenna: does it affect its gain?

piters33 wrote:

Question about painting the antenna: does it affect its gain?

At these frequencies, painting the antenna does not change anything in its parameters.

Gentlemen, I made my own clone according to the attached instructions, I think I did everything correctly, but it turns out that the reception is worse than the antenna mounted on the radio, what could be the problem?, I am providing a photo for your reference.

The fundamental question is whether the 800mm upper pipe should really be aluminum or PVC?

piters33 wrote:

...should the 800mm upper pipe really be aluminum? or PVC?.

Did you read the description or didn`t feel like it?



The dimensions of the elements are also provided, if anyone asks

That's what I read, but logically it's a bit strange to cover the radiator with an aluminum pipe, I'm asking because I did it and it doesn't work

Have you ever heard of something like stimulating a passive element with a vibrator?

Oh no