Some pics and a few notes about the rather obscure Eldico TR1-TV, which was made in 1953-4 as a TVI-proof version of the TR-1. Changes included a three-chassis design, improved filtering and shielding, and a change from an 813 to the 4E27/5-125B PA tube. Power supply, modulator, and RF deck were offered separately, or as a complete transmitter in a 28" tall rack cabinet for $379.95 (kit) or $499.95 (W&T).
This transmitter was purchased via online auction from the collection of "Vortex Joe", N3IBX, and it was clear some repairs and restoration would be required. Upon inspection, problem areas were found to include: Missing plate transformer, incorrect plate tank inductor, only partially installed, and a thick patina of tobacco residue on all surfaces. The modulator had been recapped and the power supply had been rewired, and a new wiring harness to interconnect the three chassis had been fabricated. The first task was to select a suitable plate transformer (3000 volts center tapped) and wire up a new solid-state rectifier string. Due to the size of the available transformer the replacment had to sit on a small "back porch" but did fit (barely) inside the rack with the back door closed for cat-proof safety.
The next task was cleaning - a nasty messy job that was made easy by use of my favorite degreaser/cleaner: CRC Hydroforce industrial degreaser. Yes it's $30 a gallon and yes, it's really that much better than all the rest.
After cleaning it was determined that 100% modulation could not be achieved and upon further testing, that a low impedance short existed between primary and secondary of the modulation transformer. It was replaced by an ART-13 mod transformer with good results. The plate tank inductor that was partially installed was an Airdux 195-2 which provides 16uH maximum inductance. Experimentation proved that was just not enough for this pi-net design so a homebrewed 20uH coil from the junkbox was found to be just right. Output power on 75 meters is right around 175 watts with the substitute power supply that puts out 1330 VDC under load, or 267 watts input, for an efficiency of 65%.
The TR1-TV's planned debut was foiled when after many hours of testing and dummy-load operation a slider-type variable resistor in the low-voltage (400 volt) power supply opened up. A small brass shunt was made to bridge the two sections of the exposed resistance wire and held in place with a small hoseclamp. A bit McGuyverish, but it works fine.
This TR-1-TV has shed much of what was added to eliminate dreaded TVI i the early 50s - the RF deck shielding was missing when I got it and I pulled out the built-in lowpass filter after seeing that one capacitor in it had already failed and been replaced. One of the benefits of today's digital TV technology!
The TR1-TV was most directly competitive with the WRL Globe King 400, which also was supposed to be "TVI proofed" and boasted 100 more watts. Maybe that was enough to tilt the ham buyers toward WRL, along with the company's famous founder's reputation, magazine ads, and trade-in policy, but clearly the TR1-TV did not achieve anything close to the popularity of the Globe line of large AM transmitters. It could also be that more dollars were spent on SSB gear, a market that Eldico quickly entered and achieved some success in. But the TR1-TV is a solid rig, fairly easy to work on (as long as you have good knees!) and seems to be well engineered for ease of use. The early 50s were still a time when "store-bought" transmitters were somewhat less common, but any ham purchasing a TR1-TV would have been able to use it with pride, and with fewer phone calls from upset TV-owning neighbors.