Sivertone 4663

Silvertone 4663

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This is a Tombstone radio sold by Sears. A Silvertone Model 4663 three band radio. It has standard broadcast from 540 to 1800 kHz, a 1700 to 6300 kHz police band and a 5950 to 18500 kHz SW band. http://www.nostalgiaair.org/Resources/181/M0017181.htm

Resistance is Futile

The electrical restoration was straight forward. Many of the Dog Bone resistors are way out of tolerance. They were replaced with modern 1/2w 5% carbon film resistors of slightly larger wattage. The original resistors are rated at 1/3 watt (except for R7 2w).

The 6X5 rectifier tube tested good on the emissions tester but failed to supply full B+. This tube was replaced with a custom made solid state replacement. That included two 1n4007 diodes and a 150 ohm 5w wire wound resistor. The 6X7 tube has a 22volt drop at 70ma according to Duncan Tubes TDSL tube list. That works out to be 314 ohms at full load. However, this radio apparently does not pull full load. The resistor was chosen for documented B+.

It is argued that Resistors do not drift to the extend of needing "shotgun" replacement. Below is a table of some of the resistors and what they measured. All resistors were replaced.

Resistor	Measured	Value	multiplier - 1/3 watt unless noted	%
R2	78	50	k	56%
R5	19.5	20	k	-3%
R6	47	30	k 1/2w	57%
R7	24	20	k 2watt	20%
R8	1.64	1	meg	64%
R9	88	50	k	76%
R10	1080	500	k	116%
R11	380	400	ohm	-5%
R12	46	40	ohm	15%
R14	2.36	1	meg	136%
R16	516	250	k	106%
R17	4.7	2	meg	135%
R18	300	300	ohm	0%
R19	1200	500	k	140%
R20	2.56	1	meg	156%

Once you lift a lead wire to accurately measure the resistor often it is simpler to solder in a new resistor instead of trying to splice the lead wire of the original resistor. A tiny bit of extra time can make the different between a stable daily driver or one that will revisit your work bench over and over as the each remaining original resistor drifts out of tolerance. When you restore your unit, you decide if you want to leave the resistors alone or replace them with 5 cent carbon film 5% resistors.

If you want the vintage dog bone look see here Try Syl's web site. .

I have my Eye on you!

Classic dilemma. A new eye tube cost about 25 to 45 bucks. What do you do? Try a Russian made brand new 6E5C octal based eye tube. Here is the conversion story. Acquire the new tube, an octal socket, a salvaged six pin plug some wire and a wrapper. Add an STSP switch in the B+ line and you have an adaptor with a phosphor life extending blanking switch. You could just retrofit the six pin socket on the radio. But I like the ability to use the original 6U5.