[ARC5] [Milsurplus] ARC-2 use ?

[kgordon2006 at frontier.com]

I have a really nice ARC-2, completely stock, but without control box.  I have followed Dave's 
work on his, practically from its beginning.

I intend to use mine as he has, and I am NOT going to mess with the IFs. Dave went through 
quite a bit of "research" on that issue several years ago, and I believe him.

IMHO, these are a rather unusual rig. Collins designed and (usually) built.

I will either try to find a control box, or to build a suitable substitute.

Ken W7EKB


On 23 Nov 2025 at 8:36, David Stinson wrote:

> 
> I have a nice ARC-2 which Mike Hanz helped me get running.
> On the original dynamotor with mount and control box.
> 
> 
> I tried the "change the IF interstage coupling caps"
> but there is a snag with that:
> The connections between modules and IF cans are made
> with tiny coaxial cables, and the center conductor has a very
> low melt-point; trying to disconnect these cables to facilitate
> changes, even with a lower-temp setting on the soldering iron,
> damages the center conductor's insulation.  It's very
> easy to melt it into a short.  One cannot just replace these with
> regular wiring;  the ARC-2 design uses these shielded cables and
> the metal-envelope tubes to prevent feedback between stages.
> 
> IMHO, the limited amount of improvement gained by trying to
> change those caps is not worth the real risk of damage.
> If you want to use the ARC-2 on CW, use an external audio
> filter.  Don't set the filter too narrow.  So many people, rather
> than train the "filter" between the headphones as we did
> as Novices, make the mistake of setting the digital filter in the
> "computer-with-an-antenna" they call a "radio" to 50 Hz or
> narrower.  They call CQ and someone answers them 100Hz off.
> He never hears the reply.  I believe a lot of the decline
> of CW QSOs can be laid at the feet of misused "features."
> 
> If one replaces a metal tube, you must use a metal replacement.
> Everything is so crammed into the limited space in the ARC-2,
> if you replace a metal tube with a glass, removing the metal shield,
> feedback may occur.
> 
> One change I very much recommend if you're going to do CW
> with it:  increase the BFO injection capacitor from 5 or 10 pFd
> to 50 pFd.  The stock BFO injection is weak.  This simple and
> reversible change will make a great improvement. 
> I prefer to use the ARC-2 on AM despite the broad IF.
> If you were a Novice in the early 70s, your brain
> will remember how to "pick them out of the pile."
> 
> I like the ARC-2 a lot and it has a place in my retirement shack,
> assuming the Bony Old Man with the hour glass leaves me
> be for a few more years ;-).
> I once accidentality left the ARC-2 on for 18-straight hours
> with the dynamotor chugging away.  No problems.
> 
> GL OM DE Dave AB5S
> 
>