[Lowfer] Question about surplus toroids

[Mike WE0H]

Hi Peter,

Yep for sure save those cores. They cost too much with shipping to buy 
what you can get for free from other's throw away devices. I have used 
those Yellow/White cores on 185kc lowpass filters to match output stages 
to the feedline or antenna directly in Part 15 cases. Those mystery 
black ferrite's are all over the place though. I had to finally break 
down and order some -43 & -77 ferrite's so I had a standard to check the 
mystery cores to. Even then, there are quite a few mixes of black 
ferrite's. I believe those gray painted cores are type W which are good 
for way low VLF stuff. I use them for common mode chokes on the 
feedlines for VLF receiving. You get tons of inductance per turn with 
those...hi hi...The real strange ones are the house painted toroids 
where the color code means nothing as far as I have discovered. Then you 
have to resort to matching to what you know by the charts or your 
'standard' cores you never use...hi hi...Fun collecting surplus stuff as 
long as a guy keeps it sorted and in bins.

Ever taken a CRT monitor apart and scarfed all the active components off 
the boards? A guy could run a QRP station with those components alone 
never needing to buy even wire. Ham Macguyver I think the guys call 
that...hi hi

Here's the link for that Mini Ring Core Calculator software. A must have.
http://www.dl5swb.de/html/mini_ring_core_calculator.htm

Mike
WE0H


Peter Barick wrote:
> Andy, ditto what Mike says on measuring an unknown core with a few turns.
> Also, compare the unknown for L to one of known material, ie, a known
> Amidon core as standard.
>
> But do save 'em.
> At minimum use as plain line-decoupling chokes.
>
> Nice reminder on the colors, Mke. (Another Scrounger! )  Wrote 'em down fersur.
>
> Peter  :=)