[Heath] AR-3 - another question

[Kenneth G. Gordon]

On 18 Apr 2016 at 23:28, Glen Zook wrote:

> You are reading the manual incorrectly! What it means by the dual tuning
> capacitor is there are 2-sections to the capacitor and there is a separate
> bandspread capacitor. 

Glen: the manual says nothing about a dual-tuning capacitor. Here are the exact words from 
page 3, 2nd paragraph, of the original Heathkit AR-3 manual:

"Four frequency bands, IN CONJUNCTION WITH DIRECT PLANETARY DRIVE, provide 
continuous tuning from 550 kc to 30 mc."

The next sentence reads as follows: "No communications type receiver would be complete 
without bandspread." Then: "The AR-3 has been equipped with electrical bandspread that 
operates at optimum efficiency on all frequency ranges."

So how do you interpret the bolded section above? In addition, why is there a 1/4" section of 
the main tuning capacitor shaft to which the knob is attached, and which then fits inside the 
larger section of the shaft which is then connected to dial-pulley and the rotor plates? 
Lastly, I own several NOS BC band tuning capacitors which look identical to this capacitor 
(except for capacitance values), and which ARE "verniers".

> The dial pulley is attached directly to a 1/4th inch diameter shaft

Not so: the dial pulley is connected to the larger shaft which is connected to the rotor.

> that is directly attached to the main tuning capacitor rotor. 

Not so. Look closer. The 1/4 inch shaft fits INSIDE the larger shaft which connects to the 
rotor. The 1/4 inch shaft does not connect directly to the rotor, nor to the dial-pulley. At least 
this is the case in all three of the AR-3s I have here.

> There is no reducing mechanism, of any type, in both the AR-2 and AR-3. At
> least in both of my receivers. 

Well, I don't know about the AR-2 since I don't own one, but I am almost certain that the AR-
3 DOES have one, but at this late date, it is frozen solid. I am equally certain that all other 
AR-3s which have original tuning caps have the simple vernier mechanism but are all frozen 
solid.

Anyway, I aim to find out.

Ken W7EKB
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