9cm filter?


militaryoperator
 

Would anyone have a filter of some sort suitable for 9Cms?

I am getting a lot of broad noise when I beam East, of course my best direction, so there's something that way, phone mast or such.

So, ideas?

Ben G4BXD


Graham G3VKV
 

Hi Ben,
Red block is the 10MHz wide amateur allocation from 3400 to 3410MHz (secondary),
marker on SSB calling channel 3400.2MHz
Big 50MHz wide data block (3410 to 3460MHz) to the right has been purchased and being used by Vodaphone
When it's gone it's gone ! (for a huge amount of money)
Perhaps you are near this as you say a good filter required for tx and rx
They are around -  ex Stealth 20W amplifier racks - 2 in each but need retuning !!

Graham G3VKV



Colin Ranson
 

Hi Graham, I have a water tower 500m from here exactly due east. If I beam at it (73ele QLY) the increase in noise on 3.4GHz is horrendous, a few degrees either way and it drops off substantially, don’t think its RX overload but wideband noise from Vodafone.  It may of course be phase noise in LO ? the transverter being from SG-Lab.   Any other direction is OK.  Don’t think a filter will be any good to me.

 

G3ZQU, Martin – can you confirm 3.4GHz is used on Chantry water tower ?

 

Best regards

 

Colin de G8LBS.

 

Sent from Mail for Windows 10

 

From: Graham G3VKV via groups.io
Sent: 11 June 2021 11:51
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 9cm filter?

 

Hi Ben,
Red block is the 10MHz wide amateur allocation from 3400 to 3410MHz (secondary),
marker on SSB calling channel 3400.2MHz
Big 50MHz wide data block (3410 to 3460MHz) to the right has been purchased and being used by Vodaphone
When it's gone it's gone ! (for a huge amount of money)
Perhaps you are near this as you say a good filter required for tx and rx
They are around -  ex Stealth 20W amplifier racks - 2 in each but need retuning !!

Graham G3VKV


 


Gareth G4XAT
 

Might a Pipe-cap filter be enough? The ones I have tried are excellent. 28mm tunes 2.4 and 3.4 for me 9not at the same time...)
http://www.w1ghz.org/filter/Pipe-cap_Filters_Revisited.pdf
Gareth


David Redman
 

A 22mm pipecap will tune down to 3.4GHz as well

Dave
G4IDR


On Fri, 11 Jun 2021 at 13:40, Gareth G4XAT via groups.io <g4xat=ntlworld.com@groups.io> wrote:
Might a Pipe-cap filter be enough? The ones I have tried are excellent. 28mm tunes 2.4 and 3.4 for me 9not at the same time...)
http://www.w1ghz.org/filter/Pipe-cap_Filters_Revisited.pdf
Gareth


Neil Smith G4DBN
 

The problem of using pipecaps ahead of the first RF stage is that the insertion loss adds to the rx noise figure. I would first insert a 3dB pad and see if the noise dropped more than 3dB, to help identify if it was in-band. If it drops a lot more than 3dB, it is probably caused by out of band signals, and a low-loss fairly broad filter might suffice.  If the noise is in-band, filters won't help.

Certainly worth a try with a pipecap filter if the noise is at the image or is reciprocal mixing or harmonics of digital TV or data links generated in the RX by overload.  If there is a beacon that can be used, it would be good to check the S/N of the beacon, and the noise level, both with and without the filters

Neil G4DBN

On 11/06/2021 16:21, David Redman wrote:
A 22mm pipecap will tune down to 3.4GHz as well

Dave
G4IDR


On Fri, 11 Jun 2021 at 13:40, Gareth G4XAT via groups.io <g4xat=ntlworld.com@groups.io> wrote:
Might a Pipe-cap filter be enough? The ones I have tried are excellent. 28mm tunes 2.4 and 3.4 for me 9not at the same time...)
http://www.w1ghz.org/filter/Pipe-cap_Filters_Revisited.pdf
Gareth


Michael Scott
 

Hi Ben

Minikits in Australia do, or did do, a pcb 9cm filter.

I second what others have said about pipe cap filters, Paul Wade used them in his Rover transverter. Details are on his website ( Google W1GHZ ). I made an interdigital filter for 9 cms which worked well, but it involves quite a bit of machining. I could lend it to you to see if it solves your problem before you go to the trouble of buying or making anything. I could also lend you the Minikits one as well but it won't be as good as the  interdigital one.

73, Mike G3LYP

On 11/06/2021 10:13, militaryoperator via groups.io wrote:
Would anyone have a filter of some sort suitable for 9Cms?

I am getting a lot of broad noise when I beam East, of course my best direction, so there's something that way, phone mast or such.

So, ideas?

Ben G4BXD


militaryoperator
 

Hi Mike. 

Thanks for your kind offer. I'll just do some tests as Neil suggests first with attenuators and such, see if I can determine what the noise is, and then I'll get back to you.

cheers, Ben. 



Subject: Re: [UKMicrowaves] 9cm filter?

Hi Ben
Minikits in Australia do, or did do, a pcb 9cm filter.
I second what others have said about pipe cap filters, Paul Wade used them in his Rover transverter. Details are on his website ( Google W1GHZ ). I made an interdigital filter for 9 cms which worked well, but it involves quite a bit of machining. I could lend it to you to see if it solves your problem before you go to the trouble of buying or making anything. I could also lend you the Minikits one as well but it won't be as good as the  interdigital one.
73, Mike G3LYP


Alan Beard
 

Hi all,

Similar problem here with a HackRF, noise from a mobile phone tower about 600m away.
Hil VK2AZ, is directly behind the phone tower, about 6km away.

I found an article, Evanescent Waveguide Filters, QEX  Mar 2010, Paul Wade W1GHZ

I built one for 3.4GHz and it 'did the trick'. You can see the Web SDR at:
http://www.<my email domain>:8073

I did have to 'tune' the 2.4GHz one I built by drilling right  through the waveguide
and soldering wires across, forming an iris between the two tuned sections.

The NanoVNA SAAv2 is a magic bit of test gear to make these filters.
And the PocketVNA beforehand.

Alan VK2ZIW

On Sat, 12 Jun 2021 08:36:39 +0000 (UTC), militaryoperator via groups.io wrote
> Hi Mike. 
>
> Thanks for your kind offer. I'll just do some tests as Neil suggests first with attenuators and such, see if I can determine what the noise is, and then I'll get back to you.
>
> cheers, Ben. 
>
>
> Subject: Re: [UKMicrowaves] 9cm filter?
>
> Hi Ben
> Minikits in Australia do, or did do, a pcb 9cm filter.
> I second what others have said about pipe cap filters, Paul Wade used them in his Rover transverter. Details are on his website ( Google W1GHZ ). I made an interdigital filter for 9 cms which worked well, but it involves quite a bit of machining. I could lend it to you to see if it solves your problem before you go to the trouble of buying or making anything. I could also lend you the Minikits one as well but it won't be as good as the  interdigital one.
> 73, Mike G3LYP
>
>

---------------------------------------------------
Alan VK2ZIW
Before the Big Bang, God, Sela.
OpenWebMail 2.53, nothing in the cloud.


Michael Scott
 

OK Ben. I just checked, Minikits no longer do the 9cm filter, and they no longer ship to the UK as it is too much trouble since Brexit!

I dug out mine so it is there if you need it.

73, Mike.


On 12/06/2021 09:36, militaryoperator via groups.io wrote:
Hi Mike. 

Thanks for your kind offer. I'll just do some tests as Neil suggests first with attenuators and such, see if I can determine what the noise is, and then I'll get back to you.

cheers, Ben. 



Subject: Re: [UKMicrowaves] 9cm filter?

Hi Ben
Minikits in Australia do, or did do, a pcb 9cm filter.
I second what others have said about pipe cap filters, Paul Wade used them in his Rover transverter. Details are on his website ( Google W1GHZ ). I made an interdigital filter for 9 cms which worked well, but it involves quite a bit of machining. I could lend it to you to see if it solves your problem before you go to the trouble of buying or making anything. I could also lend you the Minikits one as well but it won't be as good as the  interdigital one.
73, Mike G3LYP


g3zqu
 

The answer Colin is YES, I'm afraid !!
Martin G3ZQU


Stanislaw Ziemczonek
 

Ben,
I have few 9 cm filter from commercial devices.
Write down the parameters that this filter should meet (insertion loss, bandwidth, out-of-band attenuation) ?
73's de Staszek SP6GWB
p.s. I sent this msg to:  Military1944@... but 
it came back

Hi Mike. 

Thanks for your kind offer. I'll just do some tests as Neil suggests first with attenuators and such, see if I can determine what the noise is, and then I'll get back to you.

cheers, Ben. 



Subject: Re: [UKMicrowaves] 9cm filter?

Hi Ben
Minikits in Australia do, or did do, a pcb 9cm filter.
I second what others have said about pipe cap filters, Paul Wade used them in his Rover transverter. Details are on his website ( Google W1GHZ ). I made an interdigital filter for 9 cms which worked well, but it involves quite a bit of machining. I could lend it to you to see if it solves your problem before you go to the trouble of buying or making anything. I could also lend you the Minikits one as well but it won't be as good as the  interdigital one.
73, Mike G3LYP


militaryoperator
 


Well interesting. Thanks to a load of an interdigital filter and a Minikits pcb filter from Mike G3LYP I think I need one. 

When I beam East the noise floor rises but with the filter, either one, inline the noise floor stays the same in all directions.

Unfortunately, Minikits.au no longer list one on their website. 

So, any ideas?

Ben G4BXD


militaryoperator
 

Well, that £57.65 so far spent and I still have to make the thing myself. 

There must be someone in the UK who could mass produce these? or at least even the pcb type Minikits sold, surely.
We can't be that pathetic an engineering nation can we? 

DSCF4128.JPG

Ben.


militaryoperator
 

Well, that £57.65 so far spent and I still have to make the thing myself. 
----------------

I forgot the 2mm copper tube that hasn't arrived yet (from a UK supplier ordered days ago), another £7.87 so 

£65.52 so far!

Ben


Chris G0WUS
 

just think how much fun you will have building it Ben!!

Chris G0WUS

On 24/06/2021 12:55, militaryoperator via groups.io wrote:
Well, that £57.65 so far spent and I still have to make the thing myself. 

There must be someone in the UK who could mass produce these? or at least even the pcb type Minikits sold, surely.
We can't be that pathetic an engineering nation can we? 


Ben.


militaryoperator
 

just think how much fun you will have building it Ben!!
Chris G0WUS


You know Chris its funny the number of folk who keep telling it will be fun!! hi. 

its like Nursing School 101, day 1, lesson 1. How to lie to patients and tell them "this won't hurt" as they plunge dirty great big pipes in your arm. 

Would be a lot easier on my new miller if I ever get around to buying one. Watching Youtube videos, learning quite a lot. Long time since I was in Metalwork 101 and the teacher saying I'd never be able to operate a lathe. 

Good on Tuesday, hopefully, weather permitting I'll be on 10Ghz Sunday. 

cheers, Ben G4BXD 


Chris G0WUS
 

Ah rgr that is true what you say. I recently built something very similar to what you are about to to remove the +- LO from a kuhne 23cm box although was easier as it was larger but worked very well first time 3dB BW was about 8mhz then at the +- 28mhz suppression was more than enough for what I needed.

yes printed hairpin filters readily available for each band would be a nice thing to have specially for ease of use with what you have been doing on the bench lately with amp modules etc. I dont have the skills to calculate the measurements for such as yet. I have built many a pipe cap filter and get fairly predictable results with those now but then there are plenty of sites with those detailed

let us know how it works will be interesting for sure. But dont keep an eye the clock and work out the man hours involved HI.

73 Chris G0WUS



On 24/06/2021 14:38, militaryoperator via groups.io wrote:
just think how much fun you will have building it Ben!!
Chris G0WUS


You know Chris its funny the number of folk who keep telling it will be fun!! hi. 

its like Nursing School 101, day 1, lesson 1. How to lie to patients and tell them "this won't hurt" as they plunge dirty great big pipes in your arm. 

Would be a lot easier on my new miller if I ever get around to buying one. Watching Youtube videos, learning quite a lot. Long time since I was in Metalwork 101 and the teacher saying I'd never be able to operate a lathe. 

Good on Tuesday, hopefully, weather permitting I'll be on 10Ghz Sunday. 

cheers, Ben G4BXD 


Neil Smith G4DBN
 

On 24/06/2021 12:55, militaryoperator via groups.io wrote:
Well, that £57.65 so far spent and I still have to make the thing myself. 

There must be someone in the UK who could mass produce these? or at least even the pcb type Minikits sold, surely.
We can't be that pathetic an engineering nation can we? 

There are plenty of UK places that will do short-run machining for $$$$$$$$$$$$$$$$$$ in 500+ quantity, but nobody in the UK seems to be very interested in low volume and proto stuff. Even the Chinese fabs are not cheap for low volumes, you need 50+ items before the price gets sensible.  Xometry.com pricing is reasonable and their process is super-easy, just drop CAD files and they give an instant quote for multiple manufacturing types, volumes etc. They also manufacture in EU, with a cheaper, slower service from China. Not cheap, but very very straighforward.

There are a few UK CNC machine shops on ebay that offer prototyping services, but the ones I've looked at don't seem to have many sales, so could just be a teenager with a CNC engraver in their bedroom, not a Haas 5-axis machining centre.

I wonder if a cavity-input VLNA is perhaps the best option? No coax connectors between the gate of the input device and the resonant element to add loss and degrade the NF.  Perhaps only requiring a single resonator, with the post and cavity milled on a rotary table, or trepanned on a lathe.  Using a dielectric tuning post, so no losses in screw threads.

Neil G4DBN


As some of you are aware, my wife Caroline died on Tuesday, so I have a few** things to sort out. Machining and radio have been on hold for the last five months or so, because 24/7 caring wins in the priority stakes.

Everyone is being super nice, but for some reason, some of them are "sorry" about her being dead.  Nothing to be sorry about. Caroline had a most extraordinary life, and filled her 83 years with more living than most folks manage. She knew a bit of Morse, heaven knows how. Her father was Bermudian, met her mother in Paris and he worked as a teacher in Fayoum and Alexandria.  In 1942, when she was four, her dad was fighting in the Western Desert and her mum took her and her baby brother on an evacuation journey via Kenya and somehow across Africa to Casablanca, and from there, they managed to meet up with a convoy to get back to England.  I only found this out after watching a certain Bogart film with her. She'd never seen it.

When the film ended, she just said "it didn't look like that when I was there". I thought she must have travelled recently, but she soon put me right.  Talk about starting out with a climax and building from there. We were married for 35 years. She lived long enough to get to know her first great-granddaughter. She died peacefully in her own bed, after a sip of tea, holding my hand, listening to a Bach prelude. That's a damn good way to complete an amazing life.

She was very firm that nobody should be moping about being self-indulgently miserable after she died, and that we mustn't fuss, just get on with living. I had a play for an hour or so in the UKAC SHF contest that same evening. I'm sure she would have approved.

**understatement of the year




militaryoperator
 

There are a few UK CNC machine shops on ebay that offer prototyping services, but the ones I've looked at don't seem to have many sales, so could just be a teenager with a CNC engraver in their bedroom, not a Haas 5-axis machining centre.
I wonder if a cavity-input VLNA is perhaps the best option? No coax connectors between the gate of the input device and the resonant element to add loss and degrade the NF.  Perhaps only requiring a single resonator, with the post and cavity milled on a rotary table, or trepanned on a lathe.  Using a dielectric tuning post, so no losses in screw threads.
Neil G4DBN




You lost me at "I wonder if" Neil.   !!


Ben