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One Tube Receiver:

** Model 710 One Tube Regen Receiver/ .8MHZ-1.8MHZ & 8 – 18 MHZ. **

Overview:
This receiver is very sensitive and selective at pulling in stations from the broadcast and short wave bands from around the world. One half of a 6AN8 tube serves as an RF amplifier and the other half as a regenerative receiver. A minimal antenna length would be about 6 feet, 15 feet would be a maximum. This one tube receiver is designed to operate crystal earphones or as a tuner followed by an audio amplifier and will rival many super het receivers.
Construction:
.062 thick aluminum is used to make the following parts: The front panel is 4 3/8” high and 8” wide. The chasis is 5 1/16” deep and 8” wide. The back panel is 1 ½” high and 8” wide. The two wooden end pieces are 1 ½ “ high and 5” long each. The front panel tuning background is printed on a piece of manila folder paper and then glued to the front panel. The knobs are 1 3/8” diameter ones and an extension was added to the center one. It is made from 1/16” acrylic cut to 3/16” wide and 1 5/8” long. A Sharpie fine black pen is used to draw a line on it. It is then glued to the back of one of the knobs, using epoxy. On C5 remove all but seven plates to produce a 240pF variable and on C6 remove all plates and then replace only one that is ¾” in diameter for 20pF. These variables were originally 365pF units. Regarding coil construction… Place a used octal tube socket into a vise. Now plug in an octal tube base. Use a belt sander to reduce it to a height of about 1/8”. Now use epoxy to attach a piece of 1” thin wall PVC. The piece for the BCB coil should be 2 ½ “ long and the one for the short wave coil should be 1” long. Now wind the coils according to the coil chart on the schematic. Follow this with a good coating of acrylic spray. Note: A fine toothed blade on a table saw was used to cut the PVC pieces to length and a #62 bit to drill the small wire holes.

Operation and Trouble Shooting:
Tune in a station with the main tuning capacitor C5 and then adjust the regen control until it just begins to squeal (oscillate) , then back off just a bit. Now use the band spread tuning C6 to fine tune the station. If your receiver will not oscillate then either change R5 & R7 for more voltage at pin 7 or simply reverse the connections at pins 3 & 4 on L2 (the feedback coil).
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