[AMRadio] ART-13?


Michael D. Harmon mharmon at att.net
Thu Oct 23 23:19:46 EDT 2014


Hi Bob (and all),

The ART-13 is built like a tank, and everything about it is 
under-speced.  The dynamotor supply originally supplied with the radio 
set only delivered 1150 volts B++ to the PA.  The 813 is rated to 2000V 
CCS and 2250V ICAS in Class C amp service (CW/FM).  With 2KV at 180 mA 
on the plate, the RCA TT-5 says it's good for 275W power output.  Most 
guys who build homebrew AC supplies try to keep the B++ down to 
1200-1500V to extend life of the tubes.  The 811 modulators are 
behemoths.  A pair of them in ICAS Class B service with 1500V on the 
plates will deliver an unbelievable 340W of audio!

The biggest problem with the ART-13 as a general purpose amateur 
transmitter is threefold:  First it's only designed to operate between 
2.0 and 18.1 MHz (although there are a number of guys who use it on 160M 
AM).  Second, there's no 'VFO' per se.  The calibration book shows dial 
settings for every kHz within its range, but there's no direct 
correlation between the 'A' (Coarse) and 'B' (Fine) frequency controls 
and the frequency being transmitted. Therefore, every frequency change 
has to be spotted against a receiver on a known frequency.  The 
transmitter does have 10 'preset' (i.e. memory) channels for nets and 
skeds.  Once a frequency is programmed, a simple channel selection is 
all that's necessary to set up the transmitter for operation on that 
frequency (if you don't mind the whirring and clacking while the 
mechanical marvel is doing its thing).  Third, the ART-13 is designed to 
load an end-fed airborne wire antenna.  If you build some sort of 
matching device, you could probably load up a coax-fed or balanced 
antenna, but it wasn't designed for that application.

Whatever you do,  PLEASE don't disembowel a perfectly good ART-13 with 
the intent of 'modernizing' it!  The mil surplus guys will hunt you down 
and pin your coax!

For these reasons, I wouldn't put it in the same class as AM/CW 
transmitters of the Fifties and Sixties.  It really belongs in a vintage 
Forties 'B-29' station, along with a BC-348 and a rack full of ARC-5 gear.

My two cents worth ...
Mike Harmon, WB0LDJ
mharmon at att dot net



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