Topband: [time-nuts] Minicircuits 10% discount in December

[Jim Brown]

On Thu,11/27/2014 11:14 AM, Tim Shoppa wrote:
> The 2873000202 73 material binocular core, I buy those by the hundreds from
> Newark and hand them out like a human Pez dispenser at local radio club
> meetings. They are amazing things. Not only do I use them for 160M and
> other RF applications, but I have using them in small step-up applications
> too up to the 10W level!!!

The single turn resonance of this core is around 10 MHz, with a Z at 
resonance of about 120 ohms. Like any other ferrite core, winding turns 
will increase L as N squared, increase C as N, thus moving the resonance 
down in frequency.  I'd guess that 8 turns would move the resonance 
fairly close to 160M with Z in the range of 4-5K ohms. The catch is that 
the i.d. is pretty small, so the choke would need to be wound with 
something like one pair out of CAT5 cable.

Fair-Rite considers this a suppression part, not an inductive part, 
although it is widely used for winding transformers for MF RX antennas. 
The laws of physics don't change with what we call something, so this 
will be a fairly lossy transformer. For RX transformers, it may not 
matter (and the low Q may even help), but don't be surprised when you 
see the added resistance beyond what the turns ratio predicts. :)

73, Jim K9YC