"I received my selection of O-rings from Grainger today. I first tried ONE 1/16 x 2 5/8". It stayed on the pulleys but slipped. So I added a two more. They are actually about 0.068" in diameter, so three is close to 1/4". These stay on…"
The Fine Things are Always Hand Made
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Dave McClellan
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Dave McClellan's Discussions
SCOTT 16 6K7 FIRST AUDIO AMPLIFIER CIRCUIT QUESTION
Started this discussion. Last reply by Dave McClellan Jun 15, 2022. 2 Replies 1 Like
The schematics I have (Steve Johnson and Riders) shows that the 6K7 cathode is grounded and the bias is supplied through a 1meg resistor from the -10 volt bias divider resistor string. My radio is…Continue
SCOTT 16 HUM PROBLEM
Started this discussion. Last reply by Alex R. Whitaker Jun 13, 2022. 6 Replies 0 Likes
I started a new thread for this problem since a previous thread *SCOTT 16 CAPACITOR QUESTION" had drifted off of the original question, which was answered. The radio works, but there is a strong 60hZ…Continue
Scott 16 Capacitor Question
Started this discussion. Last reply by Dave McClellan Jun 12, 2022. 12 Replies 0 Likes
I have a model 16 on the bench for checkout. The current owner has never powered it up and asked me to check it out. It has been electrically restored in the 1985 time frame. The replacement…Continue
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"Will it work without a belt tensioner? Mine has been removed. If so, yes. "
"I did add shims to the bracket holding the tuning shaft pulley using my stock of thin brass of various thicknesses. I could tilt the pully either up or down a small amount. It made no difference, except which side of the pulley the belt climbed. The…"
"There is a slight amount of play (wiggle) in both pulleys. It is difficult to determine if the two shafts are parallel by eye. The two plates are definitely firmly attached by the 4 studs so no relative movement of the plates should occur. "
"Are the GC belts mentioned new cloth or rubber? The belt tensioner appears to have been removed in my radio, so Zenith type cloth belts cannot be used. I tried trimming the width of the 8.6" Elliot Electronics belt (quite difficult) but there…"
"I ordered and tried both the 8.8 and 8.6 and neither work. In both cases, the belt climbs up one or both pulleys and will not stay in the groove. I cut and spliced an O-ring that is about 2.5" inner diameter. It works, but is kind of stiff,…"
"The connections are definitely NOT original. After further reading on the Forum, hum originating in the 6K7 1st AF amp stage was discussed. In the original circuit, the 6K7 grid bias comes a tap on the bias divider resistor string, sourced from the…"
"The Sixteen was a fairly short-lived model that did not see much in the way of change. Since you noted the resistor was a 5%, I'm guessing (without pics) this may be a more modern replacement. Do the solder joints look "original"? If…"
SCOTT 16 6K7 FIRST AUDIO AMPLIFIER CIRCUIT QUESTION
The schematics I have (Steve Johnson and Riders) shows that the 6K7 cathode is grounded and the bias is supplied through a 1meg resistor from the -10 volt bias divider resistor string. My radio is quite different: the 6K7 cathode (and suppressor) go through an unbypassed 680 ohm resistor to ground, and the 1meg grid resistor is grounded. The resistor (5%) does not look original.In addition, in my radio the 6K7 first audio amp gets its screen supply through a 100K resistor. The schematics say…See More
"Yep, a dial light or heater string full short can get "interesting" really quickly!"
"Dave, you are not the first to encounter the dial light short problem! At least in my case it was a full short and quickly found.
Norman"
"Well, I made a rookie mistake. I apologize to the Forum for wasting your time. When I removed the tuner shield to inspect for any original capacitors left (there was one), the shield pinched a pilot lamp lead when reinstalled. In this radio, the…"
"There should be 5K resistor between the top of the voltage divider and the inverter plate.
Also poke around the bass resonator circuit ahead of the inverter.
Anyone?"
"Thanks for your response.
Some hum problems trace back to the 1st audio in some models, including the 6K7-G in the Sixteen.
The hum is there with the 6K7 removed, or its output disconnected from the inverter, or even if the inverter grid is…"
"Some hum problems trace back to the 1st audio in some models, including the 6K7-G in the Sixteen.
Illusive hum problems are a trial for sure.
The low 60 cycle ac appears only at the inverter plate and no other tube plates?
Cathode to filament leak…"
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