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Working on adding #18 to the collection.? Picked up this 5T no-Boy dial receiver that matches up with the Rider drawing attached.?
Completing preliminary checks and metering out the IF cans showed:
? First IF, primary and secondary each at 8.5 ohms.?
? Second IF primary at 95 ohms and secondary at 30 ohms.? (?)? Physically it looks fine.
I've searched and found no data and have nothing to compare against to verify the Second IF coil measurements. I read where a S-19 may be a close comparative model but I don't have one and the S-19R I do have is a different beast.

Power transformer metered out OK.? Field coil is open, dang it.? Tubes tested - The 80 tube had an open filament which was resolved by re-flowing solder into the pins, the 6F7 fails "very weak" a portion on the pentode side but no shorts.? Caps done, electrolytic 4 and 8mfds replaced with 10mfds each.? Some dogbones out of tolerance and one 100pfd mica replaced.? Subbed in a 1500 ohm for the open FC.? At initial power up on the variac and at 40vac input the 5 and 6vac reached enough that the 80 kicked in and a low B+ came up, lamps and filaments glowed.? Bringing up to 60vac sound was heard and at 80-90vac I could clearly tune in a BC station.? B+ at 250-255v.? Then, as if you threw a switch, a dominant "power" hum kicked in and the clear sound became garbled under that hum, the hum being constant despite volume position.? The power transformer began to heat up excessively, I heard a crackle or two coming from it.? And R4 (25K replaced with a 27K 1W, off B+ / screen of 6A7 in drawing) gets VERY hot. R6 is also replaced with a 27K.?

The rig is now on a test bench transformer for its supply (320-0-320), a test speaker with audio transformer, the field coil subbed by a 1500 ohm 10W wire-wound. No change in the operation, symptoms, all supply voltages come up as expected, the B+ remains pretty steady at 245-250v even when the hum kicks in 10-15 seconds after power up.? The hum may drop out and reception is clear for a few seconds before it returns, its present most of the time.? I do have a 6F7 on order as its hum suspect #1 but doubting its the root of my problem with R4 heating up.?

Also, an appropriate replacement transformer is on order.
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Dan
K1DTS

Dan:

?I would check the following capacitors? C4, C6 , C8. These all appear to be bypass capacitors going from B+ to ground. I am just thinking if they were leaky or shorted they might cause the problems you are having.

Just my 2 cents worth, and I hope it helps.


Howard, N9KTW

Thank-you.? I appreciate your response as I do all feedback I receive.? I've gained a terrific amount of knowledge on these radios from this group and all of its contributors.?
Those caps had been replaced.? The loud "hum" cutting in and out turned out to be one of the rusty trimmers on top of the 2nd IF transformer.? Just touching that one screw could cause the "hum" to come or go, ?I suppose actually a low pitched out of tune IF squeal/motor-boating.? Removal and a good cleaning of the trimmer resolved that issue.? The oddball ohm rating on the coils seems to make no difference to operation.? Replacing the 6AF made no difference to operation despite how the original tube tests. ?I replaced the power transformer with a Stancor P8306 I had on the shelf and although it's a low 40ma supply where I think a 70ma is needed, the radio is alive and working all three bands.? R4 I changed to a 2W resistor and it seems OK at that wattage.? The 1500ohm dummy load for the open field coil will stay.? Since it's going to be more of a mantle type piece rather than a daily player I may leave it that way.? Played the chassis for an hour yesterday and was pleased with it's resurrected performance.? The BFO works too.? I'll get the reworked chassis final assembled and that spring loaded belt drive tuning in working order this week.
Now for the cabinet....


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Dan
K1DTS

Calling this one complete.? I just need to add terminal posts/strip on the rear for the three antenna leads, not sure how they where originally terminated.? Only pictures I've seen show the three wires coming thru the grommet on rear of chassis and hanging there.? If anyone has a pic or details on on the antenna leads where dressed I could use the input.
Thank you.


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Dan
K1DTS

The three wires were just fed through the grommet and left hanging on all of the 5-T Sky-Buddies that I have seen. Evidently it was left to the user to connect their antenna and ground leads with clips to the appropriate wires.? ?I have a no-Boy dial version that I have restored, also an unrestored with-Boy version plus a parts unit.? Attached is a photo of the rear of my 5-T on the workbench during restoration. The black wire is ground, the yellow wire goes to the band 1 antenna coil and the red wire to bands 2, and 3 coil. That's a very nice 5-T that you have!

Les

Thank you for the follow up.? Since there's a chassis screw underside just bellow where the grommet is I'll look to put a terminal strip of sorts there.
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Dan
K1DTS