[ARC5] 400784741321

[Kenneth G. Gordon]

On 16 Oct 2014 at 15:26, AKLDGUY . wrote:

> 
> > Now hold on a minute: what about the inductors? If all you do is reduce the
> > capacitance, the L/C ratio will be horrible, "Q" will be reduced,
> 
> Did I reduce the capacitance? Yes, I did by inserting series capacitance.
> Did you reduce the capacitance? Yes, you did by removing plates.
> 
> Now, neither of us changed the inductance.

Not so. 

I completely rewound all three inductors in the receiver following the article 
that Gordon White wrote some time ago entitled, "Command Receivers for 
All Frequencies", in which article Gordon described and listed the turns on 
the coils that ARC came up with for THEIR early HF receivers up to 27 MHz. 

I used ARC's 27 MHz data, in fact, as the starting point for my coils.

> Therefore, the LC ratio will be
> horrible ***no matter what is done with the capacitance***. Does that mean that
> the unit you have in your possession has bad Q?

I don't think so. See above ;-)

> Yes, and my suggested method
> will be no worse or better than yours since we have both changed ONLY the
> *total* capacitance to get to 10m.

Ha! Wrong! As I said, I (but not only I) completely rewound all three coils in 
the front end coil box. The coils had been rewound before I got the receiver, 
but I, at least, got them correct.

I used my GDO to get the coils into the correct range, and then I covered 
them, liberally, with home-made coil dope.

Now I WILL say that your method would most certainly eliminate the 
necessity for removing any plates from the capacitors, but I STILL say, that 
the inductances would have to be "adjusted" also in order to maintain circuit 
"Q".

I also suspect that if the plates had NOT been removed from my tuning 
capacitor, and if, instead, the original hacker had simply added series 
capacitors, that the drift, microphonics, and other problems I experienced 
would have been very much minimized.

But I had to work with what I had.

Ken W7EKB