Boone
Carrie and I traveled more than 500 miles one-way to Denver, Co., to pick up this extra-long Boone superheterodyne radio. It was listed in an eBay auction with 22 other radios for one price. The seller had previously been listing many 1920s radios from the late Doug Furney collection and he didn’t seem to know anything about this superhet. There were only a couple of poor photos of the exterior of the radio and the seller didn’t want to be bothered by telling me what type of transformers were inside. I thought that it might be a Receptrad. I wasn’t interested at all in any of the other radios, but I thought that there was something special about the long superhet. To make a long story a little bit shorter, I won the auction with one bid (I was the only bidder) and sold the other 22 radios for $300 more that what I purchased the entire lot for!
Here are a few particulars of the radio:
1. It works on a variation of the Lacault “Ultradyne” modulation method of mixing the local oscillator with the received RF signal. In addition, there is a regenerative RF amplifier prior to the first detector. The circuit is actually quite advanced for the summer of 1924.
2. The engraved hard-rubber front panel measures 46” long by 7” high by 3/16” thick.
3. Boone short wave RF transformer, oscillator coupler, IF transformers, and audio transformer.
4. The tuning capacitors are unmarked but they are high quality units with gear driven vernier drives.
5. General Radio rheostats and potentiometer.
6. Eight tubes.
Top view of the chassis. The cabinet is in great shape. The electronic components look great and they are mounted on what looks like an African mahogany base board. The main problem with the radio is the hard rubber panel. The weight of the tuning capacitors over the last 95 years has caused the panel to warp. In addition to the warping, the panel is broken in a few places and there are a number of stress cracks. Hard rubber panels do not fare well over time! The panel is restorable though and definitely worth saving.
The long length of the radio allows for good spacing of the various components to help control oscillations. However, one thing I do not like is the placement of the short wave RF amplifier (first tube and transformer from the left) and the first detector (third tube and transformer from the left). The grid wire from the short wave RF transformer to the first detector tube is 14” long! That’s just inviting problems. It would have been better to put the short wave RF amplifier close to the first detector and move the oscillator (second tube and transformer from the left) somewhere else.
Close up view of the hard-rubber panel and engraving. The purpose of some of these photos is to document the original unrestored condition of this rare superheterodyne.
The two high quality gear-driven vernier tuning capacitors. The components inside the radio look like they are almost new.
Two different views of the Boone short wave RF transformer.
Two different views of the Boone oscillator coupler. The coupler fits into a standard UV type tube socket, presumably to allow quick change overs to a different frequency band. The terminals on top measure a couple of ohms and they are electrically isolated from the base terminals. The terminals on top are probably for an oscillator pick up coil that would be used in a different configuration.
Two different views of the IF transformers. Both windings are open on all of the RF transformers.
The Boone audio transformer. Both windings are good!
Schematic diagram of the Boone superheterodyne as copied from an advertisement in the August, 1924, Radio magazine. The radio works on Lacualt’s modulation method of mixing two frequencies. The plate of the first detector tube gets is supply voltage from the grid of the oscillator tube. I would like to get a copy of J. T. Boone’s superheterodyne book with a clearer image of the schematic.
Top angle view of the Boone superheterodyne. This is a magnificent superheterodyne, despite some of its faults!
Boone advertisement from the August, 1924, Popular Mechanics magazine.
Page added November 15, 2018 (updated December 31, 2018)
.