ART-13 tuning knobs very hard to turn

[K1CWS]

I am restoring an ART-13 and need opinions abt the amount of effort needed to turn the tuning knobs. When they are unlocked, they require a very tight grip and fore arm tork to turn.

Is normal, or have I missed something?

[KC4VWU]

   Make sure the locking mechanisms are actually unlocking when you turn the bars. Probably may need a little penetrating oil if it's been sitting for a while with all the controls in one spot. Let us know how it goes. I have 2 here that I'm dying to get started on, but have too much work in front of them.
73, Phil KC4VWU

[KM1H]

60-70 years of dried lubricant. Also dont try to force anything.

Overhaul is covered several places on the Internet, do a Google.

Fine rig once its working as built. Watching that autotune work is pure joy, just dont get a woody

Carl
KM1H
ATC (Navy ART-13) owner and user)

[KB2WIG]

after ya get the knobs off don't drop them... theys fragile

klc

[WQ9E]

And while you are inside, there was a suggested mod in one of the early ER issues to add a diode to keep the auto tune motor from "cooking" while it is not in use.  I don't have the issue handy but if you don't have the old issues of ER I will dig mine out and post the relevant info.  It has been several years since I went through mine and I don't recall the specifics.

Follow Carl's advice on doing the proper cleanup of the mechanism.  It is a very neat transmitter to watch and well worth the fairly small amount of time to "tune up" the auto tune mechanism.  For a long time I had mine paired with the Hallicrafters ARR-7 which has the cute and very low tech motorized search tune mechanism. (The ARR-7 is roughly the performance equivalent of the SX-28 in a very different form factor and was designed for aircraft use).

Rodger WQ9E

[WU2D]

I did some minor cleaning and lubing of the gears initially and have not done the diode. The autotune motor does get warm. I have been lucky and the rig has functioned perfectly including the autotune for going on 15 years. The ART13 has been my main transmitter.

That said, the tuning knob, heck most of the knobs are are hard to turn! The work will be worth it. Best to do this along with a complete alignment before you set it it up in your station.

Mike WU2D

[K1CWS]

I took the "A" autotune assembly off to try and see what was causing the stiffness. It seems to be a function of how tight the clutch band is. So I guess I have to live with it!

Roger, I do not have any ER mags, so if you could post the motor saving mod, I would apperciate it.

[WQ9E]

Bruce,

This modification was put together by Dennis W7QHO and is designed to keep the field winding from being energized and dissipating heat when the autotune motor is not in action.

His instructions are:

1.  Disconnect the field wire from terminal F2 of the autotune motor.
2.  Connect the cathode end of two 5 amp, 100 PIV or greater diodes to the F2 terminal.
3.  Connect one diode anode to the A1 terminal.
4.  Connect the remaining diode anode to the A2 terminal.
5.  Fuse the wires going to the A1 terminal with a 5 amp fuse to protect the field winding in case of a diode failing shorted.

I did this to mine several years ago and I don't recall it taking long to do.

Rodger