[ARC5] 10 meter BC-454

[Kenneth G. Gordon]

On 7 Feb 2013 at 0:28, john rose wrote:

> CQ magazine January 1967 has an article by Gordon White "Command Set
> Receivers for All Frequencies- The Easy Way" 

Gee....I HAVE that article....I suppose I should read it! :-)

> Max capacity of c4 part #4609 is 41 mickymikes.

Mine is about 1/2 that...which is probably just barely OK. The original article 
said to use TWO plates, then suggested ONE plate in order to spread the 
band out to the full dial. Mine is ONE plate. I calculated the maximum 
capacitance as 22 pfd. I'll measure it with a cap tester today to be certain.

> L1 6 1/8 turns #24 tin

Mine is just about exactly that, except I used #20 enameled wire. It tunes 
perfectly from 28 to 30 MHz and the trimmer capacitor is "about" centered.

> L2 14 turns #34 SSE (silk wound enameled)

Mine is 9 turns of #34 SSE, interwound with L3. I'll increase that to 14. I had 
calculated that it should be 11 turns, but 14 it will become.

> L3 6 1/8 turns #24 tin

Mine is 5 turns #20, exactly. I had calculated that it SHOULD be 7.

> L4 2 1/2 turns #32e (enameled)

Mine is exactly 2 1/2 turns #34 SSE.

> L5 5 1/8 turns #24 tin

Mine is exactly 5 turns of #20 enameled. It tunes from 28 to 30 MHz with the 
capacitor as it now is.
 
> All wound at 17 tpi

All of mine except L4 are space wound to cover the whole form.

Thanks for the info, John. As I thought, the big difference is L3 and is where 
the problem lies.

I also am just about certain that all the C4 trimmers are actually too large 
since they were originally used at the 3 - 6 MHz range.

I have two articles on making a 10 meter ARC-5: one uses the BC-454, the 
other uses the BC-455. My unit appears to have features of both articles 
combined. The article on the BC-455 suggests "ruining" the trimmers by 
yanking plates off both in each section..

At this point, I don't think that will be necessary. At least I have not found that 
necessary for the RF and oscillator sections, so I suspect it won't be 
necessary for the mixer section.

Ken W7EKB