"Old Stuff" collection

(click on any picture to enlarge)

Tube/socket 204A; KRNT-AM Farraday coil; KRNT-AM
1934 Amplifier Metering Panel; KRNT-AM  


This 204A tube assembly was removed from the 1KW AM transmitter at KRNT radio in Des Moines, IA.  Vintage of the exciter was likely early 1930's.  The 204A can be used for an RF Amplifier or a Modulator.  It is unknown at this time what the use was although my recollection is that there were four of these tubes (two assemblies) mounted on the wall of the transmitter.   

This tube is quite unique in the socket system that was used ... two non-attached ceramic bases mounted on a vertical surface.

Dimensions of the tube body is 12" long and 4" diameter.

p_204A_n.JPG (45542 bytes)p_204A_g.JPG (78493 bytes)p_204A_f.JPG (75532 bytes)p_204A_c.JPG (47032 bytes)p_204A_i.JPG (125083 bytes)

Note that the pins on the upper end of the tube are not keyed, hence this end of the tube may be inserted into the upper socket in either of two orientations.

p_204A_u.JPG (81750 bytes)p_204A_a.JPG (87979 bytes)p_204A_l.JPG (83653 bytes)p_204A_d.JPG (95977 bytes)p_204A_e.JPG (127401 bytes)p_204A_o.JPG (69924 bytes)

Note that the bottom socket is a spring arrangement allowing positive contact with the tube.

p_204A_j.JPG (80507 bytes)p_204A_k.JPG (71151 bytes)p_204A_p.JPG (84488 bytes)


This is one (of two) meter panels removed from the "home-built" amplifier at KRNT radio in Des Moines, IA.  The 2-bay amplifier was supposedly built on-site in 1934.  
The meters are hand-lettered and hand-calibrated Westons.  I was told by the "old-timers" that once the unit was completely constructed with blank meter faces,  that Weston would send a technician to do the calibration.  
The oak frame is only for display of the original meter panel with original cut-glass covering.  The five meters in this assembly are:

p_meter_g.JPG (39443 bytes)

This is the Plate Voltage meter of the assembly, full-scale reading of 15KV.  The plate transformer in this amplifier was in a large oil-filled metal cabinet, the transformer specs showing 15,000 volts @ 1 amp. 

p_meter_a.JPG (127659 bytes)p_meter_b.JPG (126728 bytes)

This Faraday-shielded coil assembly was from the output circuit of the KRNT-AM 1KW transmitter.  My recollection was that this was from the impedance matching circuit.
The outer coil is 9" long by 5-1/2" diameter.

p_faraday_a.JPG (83861 bytes)p_faraday_c.JPG (72267 bytes)p_faraday_e.JPG (98103 bytes)

Note the "taps", connection being via machine bolt. p_faraday_d.JPG (94450 bytes)

 Very common with high voltage wires of the period,
the physical wire was run through miniature ceramic beads.

p_faraday_b.jpg (59464 bytes)