[Heath] AR-3 - more

[Kenneth G. Gordon]

OK. I found the source of the bad hum with the BFO on: all the grounds for the various tube 
sockets are loose. When I tightened up the one at the 12AV6 socket, the loud hum dropped 
magnificently. ;-)

I'm going to check each ground connection, loosen each one up a bit, and apply a very 
small amount of DeOxit 5 to each, then retighten.

Also, from what I can see after examining all three of the AR-3s I have here, the main tuning 
cap does have some sort of planetary gearing built into it: the output shaft, the one to which 
the knob is connected, is 1/4" in diameter while the part of the shaft which attaches directly 
to the capacitor rotor plates is significantly larger. I have seen, and have, other dual-section 
BC band tuning caps built like these, and which have a working planetary gear-reduction in 
them, and so I am assuming that the AR-3 tuning cap is the same. 

Furthermore, there is an obvious small gap between the two portions of the shaft which has 
some brown, very deteriorated-looking, grease-like stuff oozing out of it. I suspect that the 
original planetary mechanism is now frozen solid and there is, most likely, no way to free 
that up.

But I am working on it...I've laid the receiver chassis on its back, and have applied some 
Tri-Flow oil to the shaft, hoping that some of the oil will flow between the two pieces of the 
shaft and eventually free them up a bit.

Having some sort of planetary dial reduction there would certainly make tuning easier. On 
page 3 of the original manual, the second paragraph says, "...in conjunction with direct 
planetary drive...", so, although I am not completely certain what Heathkit meant by that, I 
am assuming what I stated above is true.

Lastly, this receiver has a toggle switch added to the back-panel and two pieces of wire, one 
of which connects to the antenna connector on the back panel, and the other goes to the 
bandswitch.

Operating the switch vastly increases the audio output when the receiver is tuned to a 
station on the BC-band. I have not yet investigated exactly what this does, though.

More later.

Ken W7EKB