[ARC5] ARC-5/274-N SAelectivity

[Doran Platt]

OK, the ER article was in issue #300, May 2014.  The procedure takes about 30 minutes to do for each transformer and it requires the lower coil bobbin to the lowered, decreasing coupling.   There are several types of coil arrangements with regard to the mounting rod for the coil forms.  The article addresses both.  As I said, it does work.  But, I really have to give kudos to Norm, N3RZU, where many years ago he discussed the concept for the ARC-5 and 274N.  It wasn't until 2013 that I actually tried it, and eventually documented, what I'd done.  I tried to do the same thing with the IF cans in the wide-band BC-639 VHF receiver but the plastic encased IF coil assy. make it all but impossible.  BC-348?  The LF receivers do a fine job as a Q-5er.
Jeep K3HVG

>     On 09/27/2020 5:13 PM Doran Platt <jeepp at comcast.net> wrote:
> 
> 
>     You all mention selectivity, or lack thereof.  Have any of you all tried the modification to the IF transformers?  I done virtually all mine (except, of course, the low freq. models) and a few more for others.  Bandwidth is reduced by about 50% with very little losses measured.  Sure makes things better on 80 and 40.
>     Jeep K3HVG
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