ART 13 mods

[VK2ANJ]

Its been quite a while since this subject was raised so I thought it better to start a new topic.
I have a sentimental attachment to my ART 13 and am working to get it back on the air to join in our AM net on 40 metres.
One modification that I am trying to make is to remove the locking current in the autotune motor when it is in standby mode. This mod is often referred to but I have not been able to find out where the diode mentioned is actually inserted in the circuit. This was originally described in the December 2003 issue of ER magazine which is out of print.
Can anyone help please? It's probably very simple but completely eludes me and after a few hours the motor and associated resistor generate a lot of unnecessary heat.

[w5rkl]

I could be wrong but the following link indicates the December 2003 back issue is available for $3.75

http://ermag.com/index.cfm?v_link=product_detail&v_key=255


Email Ray Osterwald  and ask to be sure

 Ray W. Osterwald, N0DMS

73
Mike W5RKL

[W6TOM]

 I believe this mod was from Dennis, W7QHO, you might email him and ask.

[W3RSW]

There are two ART-13 articles in Dec. '03.  Tons of operating hints, maintenance ideas and suggested mods for non-collector quality ones.  Charts of auto tune settings, you name it in the first article. Also strong advice to get all the operation and service manuals you can.  Looks like getting the Dec. '03 ER issue is almost mandatory too.

Dennis' w7qho, diode(s) mod as follows from page 32, that issue:

"The military used field current to act as a brake under conditions of shock and vibration which is not necessary for our use."  
"Disconnect the field wire from terminal f2 on the motor and connect the cathodes of two 5 amp 100 volt diodes to the f2 terminal on the motor.  Then connect one diode to the A1 terminal and the second diode to the a2 terminal. This will then only provide field current when the motor is operating."
"Also as a safety measure a 5 amp fuse should be placed in the wires going to the A1 terminal for protection of the motor field in case of a short. "

[WA2SQQ]

http://www.americanradiohistory.com/

I seem to remember that ER magazine was available from this web site.
Lots of searching, and lots of good reading.

[VE3AJM]

I can scan and send you those ER articles from 2003. Let me kmow.

Al VE3AJM

[WU2D]

That is a great transmitter. The PTO is very stable. The addition of a muffin fan blowing out behind the 813/811's is a must.

I love the 160M mod and that was one of the first things I added.

A triple 365 pF variable connected from COND to ground improves the 50 OHM loading.

The speech module can be modified for better audio. Global feedback helps too.

 There is an excellent article on running high power with the ART-13 in an old 73 mag from the early 1960's in one of the surplus issues. 500 Watts on CW (of course the 811's must be out of circuit).

I grid block key mine and have timed break in and sidetone. Never did the autotune mod. The ART-13 has been a solid performer for me since 1992 wen I rescued it from the back of an OT's station wagon.