Topics

To shield or not to shield, that is the question.

Lee
 

Some have built in metal boxes, some use plastic boxes, and some put metal shielding inside the plastic boxes.  Is it a ,should do, must do, or doesn't really matter at these low power levels.   Can you also explain why you made your choice?  Thinking about options for for my JackAl add-on new radio build.
--
Lee - N9LO  "I Void Warranties"

 

Robert Evans
 


On Sat, Nov 24, 2018, 11:09 Lee <mr.olson@...> wrote:
Some have built in metal boxes, some use plastic boxes, and some put metal shielding inside the plastic boxes.  Is it a ,should do, must do, or doesn't really matter at these low power levels.   Can you also explain why you made your choice?  Thinking about options for for my JackAl add-on new radio build.
--
Lee - N9LO  "I Void Warranties"

 

Jack, W8TEE
 

If you don't care, a metal case is probably best so you can shield it. I'm doing one for my personal use that has a metal surround, but plastic end panels (easier to cut). However, the "display model" that we will use to show it off will have an acrylic U-shaped cover with an acrylic front panel and metal back panel (e.g., antenna, power, speaker connections). One of our book projects is an antenna tuner with "instant" readout of SWR on a TFT color display, which originally was in a plastic case. That project benefited from shielding, but we were testing it with 100W. We retrofitted copper foil shielding inside the case and that worked well. So, pick what looks good to you and if you think there's an RF issue, line the case with foil.

Jack, W8TEE

On Saturday, November 24, 2018, 11:09:46 AM EST, Lee <mr.olson@...> wrote:


Some have built in metal boxes, some use plastic boxes, and some put metal shielding inside the plastic boxes.  Is it a ,should do, must do, or doesn't really matter at these low power levels.   Can you also explain why you made your choice?  Thinking about options for for my JackAl add-on new radio build.
--
Lee - N9LO  "I Void Warranties"

 

Bill Cromwell
 

Hi,

Shielding also protects the receiver circuits from external "crud". So much for the QRP argument. *All of my radios live in steel or aluminum, even the one with pretty plastic panels on the outside. Those are for cosmetics only. Plastic can shield against water:) Stay indoors and it won't get wet.

73,

Bill KU8H

On 11/24/18 11:25 AM, Jack Purdum via Groups.Io wrote:
If you don't care, a metal case is probably best so you can shield it. I'm doing one for my personal use that has a metal surround, but plastic end panels (easier to cut). However, the "display model" that we will use to show it off will have an acrylic U-shaped cover with an acrylic front panel and metal back panel (e.g., antenna, power, speaker connections). One of our book projects is an antenna tuner with "instant" readout of SWR on a TFT color display, which originally was in a plastic case. That project benefited from shielding, but we were testing it with 100W. We retrofitted copper foil shielding inside the case and that worked well. So, pick what looks good to you and if you think there's an RF issue, line the case with foil.
Jack, W8TEE
On Saturday, November 24, 2018, 11:09:46 AM EST, Lee <mr.olson@...> wrote:
Some have built in metal boxes, some use plastic boxes, and some put metal shielding inside the plastic boxes.  Is it a ,should do, must do, or doesn't really matter at these low power levels.   Can you also explain why you made your choice?  Thinking about options for for my JackAl add-on new radio build.
--
Lee - N9LO /"I Void Warranties"/
//
--
bark less - wag more

Curt
 

Well when we build a radio into a metal box, then attach several wires to it, that can compromise the shielding. And cut a large opening for a display its not as shielded.

I have a slight preference for a metal case, but its effectiveness can be exaggerated.  it is a bit more effective as gathering conductors together.

When EM fields outside the box are similar to what's inside, there isn't a strong case for shielding. and even in a metal box, I remember a few rigs that require more distance away from a linear power supply.

Your choice may depend upon available packaging materials and your ability to work them. Some folk are using nice 3d printed or other plastic cases can weigh in. Nor am I trying to reduce business for a fine ubitx case maker in India.

73 enjoy your build and radiations.

Curt

Lee
 

I hope that fine case maker in India comes up with a slope front case for the JackAl add-on with options for 5" or 7" display.  I currently have a plastic case uBitx and it works fine.
--
Lee - N9LO  "I Void Warranties"

 

G1KQH
 

If using plastic boxes or the like, you can line the case and shield in important areas with copper foil available quite cheap on ebay:

https://www.ebay.co.uk/itm/99-9-Copper-Foil-Tape-Shielding-Sheet-200-x-500MM-Double-sided-Conductive-Roll/162491360479?hash=item25d53d64df:g:70gAAOSwJ4hZACVK:rk:21:pf:0


73 Steve

Gwen Patton
 

I put a plastic case on my uBitX...but I sprayed the interior surfaces with several coats of a nickel-based RFI insulating spray. It's highly conductive, and I made sure to bond all the surfaces to one another. I do suggest that a thin clear coat be put over it, as the spray can leave some loose particles. Just put painters' tape over the surfaces that need to be exposed conductor for bonding purposes, and clear-coat just enough to keep particles from shaking loose onto the board.

This is the spray I used: https://www.amazon.com/gp/product/B01N3AWGNX

I plan to do some playing with this stuff to see if one can spray an effective antenna conductor onto some sort of substrate. I'm going to try making a small transmitting loop using this stuff and a cardboard TV moving box. The box is in two parts that slide one inside the other, and am going to try using overlapping sprayed conductor surfaces to create a capacitor to tune the big loop, and put another small box with its own loop of conductor (maybe adhesive copper foil) to couple the rig to the loop. Since you can spray as wide a strip of this stuff as you want, it may be possible to get good efficiency and a wide bandwidth with it. We'll see.

It's been my experience that the spray does work to help keep RFI at bay.

Gwen NG3P

Jerry Gaffke
 

If I were to "shield" the uBitx, I'd first be shielding the various parts of the uBitx from each other.
For example, shield those high gain IF amps from the final amp.

Putting it all in a metal box can help if you have a lot of RF noisy stuff in the area.
Or if you care about some other gear hearing your BFO at 12mhz
or clk1 or clk2 or the 45mhz IF ...
I don't have either issue.

Jerry

Joe Puma
 

Interesting stuff. A person in the comments of that Amazon link wanted to know if it would block wifi and electromagnetic frequencies if you sprayed it on clothes.  Laughing my butt off!!!

 

 

Joe

 

Sent from Mail for Windows 10

 

From: Gwen Patton
Sent: Saturday, November 24, 2018 2:08 PM
To: BITX20@groups.io
Subject: Re: [BITX20] To shield or not to shield, that is the question.

 

I put a plastic case on my uBitX...but I sprayed the interior surfaces with several coats of a nickel-based RFI insulating spray. It's highly conductive, and I made sure to bond all the surfaces to one another. I do suggest that a thin clear coat be put over it, as the spray can leave some loose particles. Just put painters' tape over the surfaces that need to be exposed conductor for bonding purposes, and clear-coat just enough to keep particles from shaking loose onto the board.

This is the spray I used: https://www.amazon.com/gp/product/B01N3AWGNX

I plan to do some playing with this stuff to see if one can spray an effective antenna conductor onto some sort of substrate. I'm going to try making a small transmitting loop using this stuff and a cardboard TV moving box. The box is in two parts that slide one inside the other, and am going to try using overlapping sprayed conductor surfaces to create a capacitor to tune the big loop, and put another small box with its own loop of conductor (maybe adhesive copper foil) to couple the rig to the loop. Since you can spray as wide a strip of this stuff as you want, it may be possible to get good efficiency and a wide bandwidth with it. We'll see.

It's been my experience that the spray does work to help keep RFI at bay.

Gwen NG3P

 

mark audacity romberg
 

For $36 I think I’ll just use a metal enclosure, yikes.

Mike Short
 

That’s what foil is for

On Sat, Nov 24, 2018 at 1:42 PM Joe Puma <kd2nfc@...> wrote:

Interesting stuff. A person in the comments of that Amazon link wanted to know if it would block wifi and electromagnetic frequencies if you sprayed it on clothes.  Laughing my butt off!!!

 

 

Joe

 

Sent from Mail for Windows 10

 

From: Gwen Patton
Sent: Saturday, November 24, 2018 2:08 PM
To: BITX20@groups.io
Subject: Re: [BITX20] To shield or not to shield, that is the question.

 

I put a plastic case on my uBitX...but I sprayed the interior surfaces with several coats of a nickel-based RFI insulating spray. It's highly conductive, and I made sure to bond all the surfaces to one another. I do suggest that a thin clear coat be put over it, as the spray can leave some loose particles. Just put painters' tape over the surfaces that need to be exposed conductor for bonding purposes, and clear-coat just enough to keep particles from shaking loose onto the board.

This is the spray I used: https://www.amazon.com/gp/product/B01N3AWGNX

I plan to do some playing with this stuff to see if one can spray an effective antenna conductor onto some sort of substrate. I'm going to try making a small transmitting loop using this stuff and a cardboard TV moving box. The box is in two parts that slide one inside the other, and am going to try using overlapping sprayed conductor surfaces to create a capacitor to tune the big loop, and put another small box with its own loop of conductor (maybe adhesive copper foil) to couple the rig to the loop. Since you can spray as wide a strip of this stuff as you want, it may be possible to get good efficiency and a wide bandwidth with it. We'll see.

It's been my experience that the spray does work to help keep RFI at bay.

Gwen NG3P

 

Jack, W8TEE
 

Keep us informed!

Jack, W8TEE

On Saturday, November 24, 2018, 2:08:31 PM EST, Gwen Patton <ardrhi@...> wrote:


I put a plastic case on my uBitX...but I sprayed the interior surfaces with several coats of a nickel-based RFI insulating spray. It's highly conductive, and I made sure to bond all the surfaces to one another. I do suggest that a thin clear coat be put over it, as the spray can leave some loose particles. Just put painters' tape over the surfaces that need to be exposed conductor for bonding purposes, and clear-coat just enough to keep particles from shaking loose onto the board.

This is the spray I used: https://www.amazon.com/gp/product/B01N3AWGNX

I plan to do some playing with this stuff to see if one can spray an effective antenna conductor onto some sort of substrate. I'm going to try making a small transmitting loop using this stuff and a cardboard TV moving box. The box is in two parts that slide one inside the other, and am going to try using overlapping sprayed conductor surfaces to create a capacitor to tune the big loop, and put another small box with its own loop of conductor (maybe adhesive copper foil) to couple the rig to the loop. Since you can spray as wide a strip of this stuff as you want, it may be possible to get good efficiency and a wide bandwidth with it. We'll see.

It's been my experience that the spray does work to help keep RFI at bay.

Gwen NG3P

roger wincer
 

It must be metal. A basic of building good radio equipment. It keeps unwanted RF out and in. 
Shielding is also a basic. Take a look inside any commercial transceiver and you will see it. Lay out is important too, keep inputs away from outputs.

I have built uBitx into the case of an old Kenwwod TS120S and and it has worked out quite well.

Roger ZL2RX

Harvey
 

You can get copper EMI tape on ebay for much less than the cost of the spray. When you overlap the edges it is conductive from one piece to the next. Same stuff used in tv sets and monitors to provide shielding over some flat cables.

Harvey, WA2AAE

ajparent1/KB1GMX <kb1gmx@...>
 

On Sat, Nov 24, 2018 at 11:08 AM, Gwen Patton wrote:
This is the spray I used: https://www.amazon.com/gp/product/B01N3AWGNX

Yes MG chemical super shield (spray nickel flake).  I've used it for making plastic cases
RF tight and turning plastic shapes and surfaces conductive enough to use as antennas.
When dry it runs about 1ohm per square inch which is fairly good conductance as well
as magnetic.

I'd not advise spraying it on clothes and using a respirator if one is nickle metal sensitive.
FYI definitely spray it outdoors.  Be careful as some plastics can be attached by the solvent
in the spray.

Allison

Carlos E. Wenzel <Ik2yra@...>
 

My bitx40 is on the original plastic box... Because it's not really end it. I'm planning to update to a metalica one. 
My ubitx has a aluminum container.
Shielded and hard protected. 
Carlos 73's IK1YRA KD2QKE LU4AE 


Il sab 24 nov 2018, 19:09 Lee <mr.olson@...> ha scritto:
Some have built in metal boxes, some use plastic boxes, and some put metal shielding inside the plastic boxes.  Is it a ,should do, must do, or doesn't really matter at these low power levels.   Can you also explain why you made your choice?  Thinking about options for for my JackAl add-on new radio build.
--
Lee - N9LO  "I Void Warranties"

 

Jon Tabor
 

I put my bitx40 in a metal "collectors" Star Wars tin I had kicking around (I say "collectors" because they're not really collectible -- they sold millions of 'em, and my friend had a pallet's worth in his garage). The metal is a bit thin, leading to some flexing when you plug/unplug peripherals, but it's just the right size and easy to work with, while providing some shielding.

Plus it looks kinda neat, even if my fabrication skills are lacking.

--
Jon Tabor KI7JYE http://obsolete.site