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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th Apr 2020, 2:53 pm   #21
Julesomega
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Default Re: 6 metre 4 pole filter

I used the Toko S18 series. For oscillators it is better to fit the aluminium tuning slugs to avoid hum being coupled into the coil from nearby transformers, though this needed more turns - though not relevant in this application
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Old 10th Apr 2020, 7:28 pm   #22
Jon_G4MDC
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Default Re: 6 metre 4 pole filter

I have been looking for a one dot ferrite.
I'm sure they existed althought my present stock seems to only consist of 2s and 3s.

The Coilcraft ones I remember now, my top vote is still with Toko.
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Old 11th Apr 2020, 8:26 am   #23
g4wim_tim
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Default Re: 6 metre 4 pole filter

Hi Guys,

thanks for all the useful information on the Toko coils and possible replacements etc.

I'll likely stock up on a range for my next project !

73 Tim
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Old 11th Apr 2020, 10:19 am   #24
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Default Re: 6 metre 4 pole filter

I have always found them very useful.
I must put right my howler from previous post that 8.5T was white!
That would have to be 9.5T wouldn't it.
In fact although it should be grey the actual former is clear.
That is the same with another I have here which is 1.5T , it is also clear.
Come to think of it I have never seen a brown one.
Red and Orange have confirmed sightings
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Old 11th Apr 2020, 1:02 pm   #25
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Default Re: 6 metre 4 pole filter

Hi Jim and others..... as it happens I guessed the sizes.. ish and I had some green Toko 5.5T formers.. only 4 sadly..so I made some formers at 6mm and wound with 20 swg but I couldnt thread the centres as I dont have any taps of that thread.. UNF I guess.. so I used poly spaced trimmers for adjustment.
I am working on the 2 metre filter at present and I am nearly there..what with coupling distance,, tuning and coupling, its like spinning plates.. trying to keep them all in the air.
I am looking at the Coilcraft data, and I think I will pre test with home made formers and then order from them.. as in RAPID supplies.
Good job this project has no time limit..
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Old 14th Apr 2020, 2:59 pm   #26
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Default Re: 6 metre 4 pole filter

Hi Peeps...... Continuing on this thread....has any one any opinions regarding Aluminium or Brass for inductor adjustments. I have ordered some "Green" Toko type coils and I understand these will come with Aluminium cores.
To enable me to carry on.. I made some formers on the lathe and threaded internally at 4mm. I made some brass cores X 10mm.... and these do reduce the inductance as expected.. then I found some Aluminium bar and made some cores again at 10mm.
My question is..... ALLY or BRASS... from an efficiency point of view, as in loss "Q" etc..
They both work to reduce the inductance.
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Old 15th Apr 2020, 12:51 am   #27
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Default Re: 6 metre 4 pole filter

I had an ARRL article somewhere that had a bit about this but it seems to be hiding at the moment.

The main difference from memory was temperature effects on the tuning and I "think", aluminium was slightly worse in the drift with temperature dept.

Whether that will be enough to cause problems could be easily tested by setting up an oscillator with a coil and the two different slugs and taking some measurements at a few different temperature points.
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Old 15th Apr 2020, 10:12 am   #28
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Default Re: 6 metre 4 pole filter

Hi Terry.......Hmmmm I didnt think about the temperature..But in this case its just for "slugging" filter inductors.... I have both Brass and Ally bar... so its a case of which is to hand .... as far as oscillators go.. I would use a DDS module anyway...except for a BFO of course .. Thanks
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Old 15th Apr 2020, 11:16 am   #29
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Default Re: 6 metre 4 pole filter

Then my choice would be brass.
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