Ferrites for hydrogen line receiver systems

[Andrew Thornett]

Rich discussed these in RTOP tonight

 

How about this one?

 

NiZn Ferrite Toroid R40C1- 37x23x7mm, for High Q SW balun & Crystal Radio Coils | eBay UK

 

Price only £4.30 each – would this give the specifications required for hydrogen line systems?

How useful do folks think they are to remove RFI?

 

Andy

[Alex P]

Exactly where are these to be installed " to remove RFI " ??

[Andrew Thornett]

It was discussed tonight. This is one of the questions I was thinking - where is best place to put them, if using them is of help.

Andy

Sent from Outlook for Android

---

From: 'Alex P' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: Sunday, October 5, 2025 10:17:55 PM
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: [SARA] Re: Ferrites for hydrogen line receiver systems

 

--
--
You received this message because you are subscribed to the Google
Groups "Society of Amateur Radio Astronomers" group.
To post to this group, send email to sara...@googlegroups.com
To unsubscribe from this group, send email to
sara-list-...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sara-list?hl=en
---
You received this message because you are subscribed to the Google Groups "Society of Amateur Radio Astronomers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sara-list+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/sara-list/045430a4-26bd-4ab8-90ce-aeb2bf1ab70cn%40googlegroups.com.

[Dr. Rich Russel]

Got this from AI

This NiZn ferrite toroid (R40C1, 37×23×7 mm) is likely optimized for shortwave (SW) and low-VHF applications—not ideal for 1420 MHz hydrogen line work.

 Recommended Ferrite Materials for 1420 MHz

✅ Fair-Rite Type 67 (Material #67)

• Frequency Range: 200 MHz – 2 GHz
• Optimized for: VHF/UHF applications, including L-band
• Use Cases: Cable chokes, baluns, impedance transformers
• Examples: FT50-67, FT82-67, Fair-Rite 2673002402
• Why it's ideal: High impedance at 1420 MHz, low loss, good suppression of common-mode currents

⚠️ Fair-Rite Type 61 (Material #61)

• Frequency Range: 200 MHz – ~1.5 GHz
• Use Cases: RF transformers and chokes
• Examples: FT50-61, FT82-61

You can buy Fair-Rite Type 67 ferrite toroids from electronics distributors like Digi-Key, Mouser, and Fair-Rite directly—but availability may vary.

Here’s how to source them effectively:

🛒 Trusted Distributors for Type 67 Ferrites

1. Fair-Rite Products Corp.

• Website: fair-rite.com
• Direct source for part numbers like 2673002402 (Type 67 toroid)
• Offers datasheets and bulk ordering

2. Digi-Key Electronics

• Search for: “FT50-67”, “FT82-67”, or “Fair-Rite 67 material”
• Often stocks small quantities for prototyping
• Ships quickly within the U.S.

On Sunday, October 5, 2025 at 03:18:00 PM MDT, 'Alex P' via Society of Amateur Radio Astronomers <sara...@googlegroups.com> wrote:

Exactly where are these to be installed " to remove RFI " ??

On Sunday, October 5, 2025 at 5:07:54 PM UTC-4 Andrew Thornett wrote:

Rich discussed these in RTOP tonight

 

How about this one?

 

NiZn Ferrite Toroid R40C1- 37x23x7mm, for High Q SW balun & Crystal Radio Coils | eBay UK

NiZn Ferrite Toroid R40C1- 37x23x7mm, for High Q SW balun & Crystal Radi... When winding a coil, in order to smoothly un-coil the Litz wire from the paper spool, the simple method is: Vert...

 

Price only £4.30 each – would this give the specifications required for hydrogen line systems?

How useful do folks think they are to remove RFI?

 

Andy

[Dr. Rich Russel]

More AI answers - Looks correct.

Rich

Best Ferrite Placement for 1420 MHz Applications

1. Feedline Choke (Common-Mode Suppression)

• Where: Place the ferrite choke at the antenna feedpoint or where the coax enters your receiver or preamp.
• Why: Suppresses common-mode currents that can distort your signal or introduce noise.
• How: Wind 3–5 turns of coax (e.g., RG-58 or RG-142) through a Type 67 toroid (e.g., FT82-67). For higher impedance, use multiple stacked toroids or more turns.

2. Balun or Transformer Core

• • Where: Inside your antenna matching network or preamp input stage.
  • Why: Ensures proper impedance transformation and isolation at 1420 MHz.
  • How: Use a Type 67 toroid with carefully calculated turns ratio. Keep leads short and symmetrical to minimize parasitics.

  3. Power and Control Lines

  • Where: On DC power cables, USB lines, or control wires entering your RF enclosure.
  • Why: Prevents conducted EMI from coupling into sensitive RF paths.
  • How: Snap-on ferrite beads or toroids (Type 67 preferred) placed as close as possible to the entry point.

  4. Receiver Input or LNA Output

  • Where: Just before the receiver input or after the low-noise amplifier (LNA).
  • Why: Blocks RF leakage or feedback into the signal chain
  • How: Use a small toroid or bead with minimal turns to avoid insertion loss.
  • 
    
    

To view this discussion visit https://groups.google.com/d/msgid/sara-list/FRWP194MB2752AB8B15CCE38CD2278A4EFFE2A%40FRWP194MB2752.EURP194.PROD.OUTLOOK.COM.

[b alex pettit jr]

Winding " 3–5 turns of coax (e.g., RG-58 or RG-142) through a Type 67 toroid " creates a Guanella Current Balun to

prevent radiation from the outside of a coaxial cable  when connected to a balanced load . It is not applicable to RFI removal.

That is why either tuned cylindrical waveguides or cavity filters are used ..

Putting a toroid on a coax will  have little effect : THAT is the purpose of a coax : RF energy is transmitted within the region between

the inside surface of the shield and the outside of the inner conductor.

Alex

=================================================================

[b alex pettit jr]

WiFi dish dipole feeds use 1/4WL matching sections to keep the energy inside the coax..

=================================================================

[Dr. Rich Russel]

Alex,

Would it be useful to put on everything else but the coax? Like power supplies, usb, etc...?

--
--
You received this message because you are subscribed to the Google
Groups "Society of Amateur Radio Astronomers" group.
To post to this group, send email to sara...@googlegroups.com
To unsubscribe from this group, send email to
sara-list-...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sara-list?hl=en
---
You received this message because you are subscribed to the Google Groups "Society of Amateur Radio Astronomers" group.
To unsubscribe from this group and stop receiving emails from it, send an email to sara-list+...@googlegroups.com.
To view this discussion visit

https://groups.google.com/d/msgid/sara-list/1294274072.2265237.1759702380087%40mail.yahoo.com

.

[b alex pettit jr]

I tried blocking radiation from a USB over CAT cable extender which used not twisted pairs for transmission .. minimal effect.

You can try, but ... Ferrites are not  "Silver Bullets"   .. I did extensive research on them   10+ years ago for 20 meter apps.

Type 61 material is probably the best for atten at 1.4G

Hopefully, power supplies are Linear or not in the near proximity to the antenna.

I found Monitors to be horrendous radiators.. best orientation is to have them edgewise to the antenna  or make a 5 sided foam core board box  lined  with Faraday Fab.

===============================================

[b alex pettit jr]

https://fair-rite.com/materials/

Ferrite materials increase the inductance of a coil.

It is the high frequency equivalent of using iron laminations in a 60 Hz transformer.

Ferrites have Permeability .. an inductance multiplier 

For instance, below are curves for Type 61 material .. up to ~ 10MHz, it is effective and

creates a low loss inductance .  it has good Permeability up to 10MHz .. 

Beyond that, the Permeability decreases and Complex Permeability becomes dominant 

Complex Permeability is a 90 deg phase in Inductance .. meaning it transitions into a Resistance .

This is bad for a transformer ( will get Hot ) , but fine for a common mode choke .. as either Inductance or Resistance

will create an 'impedance' to the current flow and that is the goal of preventing current ( radiation ) from the outside of a coax cable shield.

Prof P

     Permeability u'

     Complex Permeability  u''

Type 67 material

Type 43 material