[ARC5] Receiver audio transformers and other stuff.

[Kenneth G. Gordon]

On 20 Jan 2013 at 7:04, David Stinson wrote:

> > Does anyone have a decent idea of the reliability of T-1, 
> > the receiver audio transformer?
> 
> New one on me, Ken.  I've been working with these sets
> off-and-on for decades and have rehabbed a great many.
> I've never seen a failed receiver audio output transformer.

Well, the one I am presently working with is one of the older ones with the 
8000 ohm winding and a 600 ohm tap on the output side. The "sealer" is not 
mica, but phenolic. The number on it is ES-XXXX.

The primary IS open, and it is not at the connections as I have removed the 
"posts" and the wires are intact down into the core. The break has to be 
somewhere inside the core. There is also no continuity even to the tap that 
goes to the neon bulb.

I have a second transformer, which still has the ARC logo on it in yellow. This 
one is one of the "newer" ones with only the 600 ohm output, and which is 
"sealed" with mica. It is still good.

Kinda tees me off.

The receiver I am working with, a BC-454 had been hacked. It has a large 
"window" cut into the top of the outer case, and a piece of mash bolted in, 
apparently in an effort to improve ventilation.

The RF/Oscillator coil box had a masking-tape label on it. Most of the words 
were illegible, but one could make out "Mod...." and 28.

Yanking the tuning cap cover, I discovered that all of the rotor plates but one 
have been removed from all three sections of the tuning cap, the antenna 
connector has been replaced with an RCA jack, a piece of what looks like 
RG-174 run down to the input connectors (both of which were broken loose 
from their mica and shoved up inside), and after I opened up the coil-box, I 
discovered that this particular receiver had been modifed to tune 28 to 30 
MHz.

Crap! I am not pleased. :-(

Ken W7EKB