I believe the red triangle was an indicator as to whether the T bar was locked,  or not.  If not locked, the channel "memory" would be mechanically lost if the autotune was actuated via the channel selector.  Looking at the indicator disk, you'll set a small Ridge that the T bar will contact as it's being locked. 
Jeep K3HVG
On 02/25/2026 11:34 PM EST Hubert Miller <[email protected]> wrote:
 
 

Do you mean, the red knob paint means the transmitter was not used in autotune ( preset channel )

mode ?

-Hue Miller

 

 

On Behalf Of Doran Platt via ARC5
Sent: Wednesday, February 25, 2026 5:50 PM
To: arc5

Subject: Re: [ARC5] ART-13 knobs question

 

My experience with over 20 T-47, T-47A, and ATC units has most of the autotune knob locking plates having red triangles painted the to indicate, I think, an unlocked knob.  The locking T bar is black. 

Jeep K3HVG

 

On 02/25/2026 6:52 PM EST Hubert Miller  wrote:

 

 

I  had never noticed the difference in color of the knobs on the ART-13.
Kinda reminds me of this puzzle in the local newspaper – “Find 6 differences in the drawings”

and the tendency is to overlook what’s “not important”.

So why the red knob skirts and some black ?

Photo via Julyah, pres of the PSARA antique radios club.

-Hue Miller

______________________________________________________________
ARC5 mailing list
Home: http://mailman.qth.net/mailman/listinfo/arc5
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]

This list hosted by: http://www.qsl.net
Please help support this email list: https://www.qsl.net/donate.html