[Elecraft] CP1 Power Handling

[akbiocca at comcast.net]

Stacking cores can also help increase power handling capability without taking more pcb space (providing the core is flat on the pcb).

-- Alan wb6zqz

-------------- Original message -------------- 
From: Larry Phipps <larry at telepostinc.com> 

> A quick check shows that no small size cores will work for -43 material 
> with 10T at 1.8 MHz and 200W. However, FT50B cores come close, and are 
> fine at 3.5 MHz. FT50B is twice the thickness of the FT50A, and would 
> fit on the board because the thickness would only add height. 
> 
> 73, 
> Larry N8LP 
> 
> 
> 
> Linden, Mike (BRC-Hes) wrote: 
> > Larry, 
> > 
> > If you have the time, I'd certainly appreciate it if you'd run it 
> > through your spreadsheet for me. 
> > 
> > Thanks! -Michael 
> > 
> > ======================================================================== 
> > ====== 
> > 
> > You have a couple options. The flux density is higher, and therefore 
> > heating, with lower number of turns. They also go to a -43 mix (higher 
> > permeability) for the lower turns to keep the shunt reactance of the 
> > voltage xfmr high at 1.8 MHz. 
> > 
> > If you don't care about 1.8 MHz, you might be able to get by with 10 
> > turns on the -61 cores... I would have to do the math. The other option 
> > is to stick with the -43 material, but get larger cores. I'm pretty sure 
> > they make the FT50A and FT50B (which are thicker) in -43 material, or 
> > you could go to a FT68 or FT82 if they'll fit. The best bet would 
> > probably be FT50A-43, since we know it would fit physically. I have a 
> > spreadsheet that I use that calculates these things for me... I can plug 
> > these in to see what would work if you like. 
> > 
> > 73, 
> > Larry N8LP 
> > 
> > 
> > Linden, Mike (BRC-Hes) wrote: 
> > 
> >> Does anyone know what modifications would need to be made to the CP1 
> >> 
> > 
> > 
> >> Directional Coupler in order to get it to handle 200W at 20dB 
> >> attenuation? 
> >> 
> >> I'd like to use the CP1 as a cost effective means of extending the 
> >> useful range of my OHR WM-2 QRP Wattmeter, but 30dB is more 
> >> attenuation than I want and the power handling at 20dB is not high 
> >> 
> > enough. 
> > 
> >> Thanks, Michael N9BDF