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#1 2008-08-12 14:12:28
- W8DIZ
- Administrator
- Registered: 2008-08-12
- Posts: 317
LPF - SIngle Band Low Pass Filters - 7 Pole
Build these 7-pole Universal Low Pass Filters for $8.
Available for 10, 12, 15, 17, 20, 30, 40, 80 and 160 meters.
http://kitsandparts.com/univlpfilter.php
-Diz, W8DIZ
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#2 2008-08-30 07:28:43
- vk2nda
- New member
- Registered: 2008-08-12
- Posts: 8
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
Hi,
I started on my 40m LPF the other day. I've been using my new LC meter, and getting use to it. Anyway...after winding the toroids I cut off excess length on two, and then found them to have a lower inductance due to making an incorrect adjustment based on an erroneous reading I took.
What gauge of wire is used for these toroids so that I can buy a roll locally?
Thanks,
Nick
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#3 2008-08-30 12:03:47
- ak2b
- Administrator
- From: New York City
- Registered: 2008-08-12
- Posts: 338
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
Hi Nick,
This is an educated guess by comparing the left over wire from my LPF and comparing it to other labeled wire that I have. Plus looking at what Diz sells on his website http://kitsandparts.com/magnetwire.htm and seeing that the #28 wire is not heat stripable as is the wire that comes with the LPF kit, I would say it is #28 
. I think anything around that guage is going to be fine since you are measuring it anyway.
Tom, ak2b
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#4 2008-08-30 14:39:46
- kc0wox
- Member
- Registered: 2008-08-12
- Posts: 65
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
28 will work for most of the home projects. Did you get a LCII meter? I love mine. I find on a lot of toroids I need 1 turn less than stated to get the values listed.
Leonard
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#5 2008-08-30 21:36:24
- vk2nda
- New member
- Registered: 2008-08-12
- Posts: 8
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
Thanks Tom and Leonard,
Hopefully I will find some heat stripable #28 wire at the shop up the road.
No I didn't buy an LCII. I considered it awhile ago and then Silicon Chip Magazine in Australia put out a kit based on the LCII design. This re peaked my interesting in getting back to the kits. They appear very similar in specifications although I have not looked at the LCII construction manual to review it's circuit diagram.
Out of interest Leonard, is the LCII effected by hand capacitance? I've noticed that if I place my palm close to where the internal oscillator is the stray inductance reading will spike. The strays also go up and down by about 10nH-30nH but go away after I zero it a few times in say 5 minutes. I'm confident I'm getting repeatable results now that I've gotten use to it over the last few days.
http://www.altronics.com.au/index.asp?a … p;id=K2533
Yes, from the few toroids I've wound since having the LC meter I too have observed that I need 1 turn less, or there abouts.
Nick
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#6 2009-02-21 11:07:34
- ak2b
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- From: New York City
- Registered: 2008-08-12
- Posts: 338
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
N2PK VNA scan of the 40 meter LPF. Looks good.
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#7 2009-02-21 16:30:39
- kc0wox
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- Registered: 2008-08-12
- Posts: 65
Re: LPF - SIngle Band Low Pass Filters - 7 Pole
Nick:
If you email me or PM me your address, I'll send you an assortment of some wire.
Leonard
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