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+---- Thread: 8 JUN BALUN PRESENTATION (/showthread.php?tid=507)
8 JUN BALUN PRESENTATION - VE3WI Dave - 2021-06-08
I've attached the slides I presented tonite. I converted it to a PDF to reduce the filesize below the forum limit, so all my cute animations are gone.
If you have any questions, please post here & I'll try to get you an answer.
Thanks for your attention.
73
Dave, VE3WI
RE: 8 JUN BALUN PRESENTATION - VE3WI Dave - 2021-07-13
In the presentation I mentioned that the big parts houses probably have better prices for ferrite toroids than the well known ham suppliers like Palomar Engineers & Amidon Associates.
I did a little research for prices on a 2.4" OD Mix 31 toroid (Fair Rite part # 2631803802). This is the one you'd most likely want to use. I did the US$-CDN$ conversion on xe.com.
Vendor US$ CDN$
Palomar.com $10 $12.51
Amidon.com $10 $12.51
Newark.com $5.10 $6.38
Mouser.com $7.55 $9.45
DigiKey.com $8.31 $10.40
(MFJ doesn't list this item)
Canadian websites:
Newark.ca $7.09
Mouser.ca $10.42
DigiKey.ca $11.82
I was impressed by the US Newark price. I expected that I would get bounced to their Canadian website when I tried to order, but they actually processed the order. Can't go wrong at that price! I ordered 10, so if anyone wants one I'll sell it to you for my cost.
73
Dave, VE3WI
RE: 8 JUN BALUN PRESENTATION - VE3WI Dave - 2022-01-14
I found a design chart by Glenn, W9IQ for common mode coax chokes using Mix 31 ferrite toroids, that is simpler than the G3TXQ chart in my presentation. See attached. 12 turns on a FT240-31 looks like the best compromise over most of the HF bands. If you need even wider suppression range, put a 14-turn in series with a 10-turn.
W9IQ specifies very expensive RG400 teflon coax. Good quality RG58 (with solid dielectric & 95% braid) is the same size & should work fine unless you're running a big amp. The stranded center conductor type would be definitely preferred over solid single conductor, for ease of winding. Don't use the foam dielectric type.
Solid dielectric stranded conductor RG58C/U is listed for $0.39/ft at Maple Leaf Comm http://www.mapleleafcom.com/ (although Bob is trying to retire & has moved some products to other sellers)
Cheapest RG400 I've found is Chinese stuff from amazon.ca at $43 for 20 ft. Aircraft Spruce in Chatham has it for $5.40/ft (ouch) https://www.aircraftspruce.ca/
73
Dave, VE3WI