[ARC5] IF transformers.

[Kenneth G. Gordon]

On 16 Jun 2013 at 10:34, neilb at ihug.co.nz wrote:

> > The dot on the top of the "1st" IF can is reversed from the other two,
> > and is "pointing" toward the back instead of the front.
> 
> What is the significance of the dot being reversed?

All three of the IF cans in any "ARC-5" receiver are marked with a colored dot on one corner 
of the top of the cover. The dots are usually different colors, possibly to indicate their 
frequency. 

When all three IF cans are properly installed, the three dots on the three cans will all be "lined 
up" and will all be "pointing" in the same direction: to the front-right corner. The dots, when 
combined with the base and properly lined-up essentially indicate that everything is correct.

The center IF can, due to its base, can only be mounted in the center. It cannot be reversed, 
either, due to the plug in the chassis...except in some receivers in which the chassis plug 
does not include all 6 posts. Usually these are the 6 - 9.1 MHz versions which have simplified 
IF cans.

In addition, at the bottom of each can, a colored "bar" is painted across the bottom and up 
the side for a short distance. The purpose of this bar is to indicate the correct mounting of the 
IF can cover so that the two holes on the top of each cover reveal the correct numbered 
capacitor when aligning. The color of that bar is red for the 1st IF can, yellow for the 2nd IF 
can, and blue for the 3rd IF can.

The two "outside" cans have bases on them which allow them to be mounted in only one 
direction, (except in those receivers in which the chassis-plug does not include all 6 posts) 
AND the bottom of each IF can has a mica-insulated socket that matches the mica-insulated 
plugs in the receiver. 

The rear-most IF can (3rd IF can) can only be plugged into the front-most (1st IF) socket (or 
vice versa), if the base is removed and reversed.

> Are you implying
> that this IFT has been inserted back-to-front? 

Yes.

>Is that possible?

Only if the mounting base is removed and reversed. I suspected that this was the case since 
at least one other of these hacked receivers I have here had had that done to it back in the 
1970s.

> Or is it *necessary* in order to make IF transformer 3 fit into the IF
> transformer 1 socket?
> Or has the can simply been rotated 180 degrees on its base?

Neither, in this case:

On closer examination of that 1st IF can, I discovered yet another 70+ year old assembly 
error: the cover on the 1st IF can had been installed backwards, the cover screws installed, 
and the red-locking-paint applied. The cover had, obviously, never been removed since it 
was made.

I removed the cover and reversed it to its correct position.

All is right with the world once again. :-)

Ken W7EKB