I picked up a nice SB200 as i hooked everything up including a foot pedal to key amp i found out that it does not key up. I already know of the high voltages in this amp so i am being very careful and am ordering a high voltage probe to plug into my Triplet meter and MM-1 heathkit meter to check the high voltages. I see relay and checked voltage to it and it looked like -60dc volts but it is a 120vdc relay i believe. Any help will be appreciated.
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SB200 Heathkit no key up.
- Thread starter Jimbo165
- Start date
Heathkit used a 120-Volt AC-coil relay with a coil resistance of around 3000ohms, if memory serves. Has a 2000 ohm resistor in parallel with the coil, and a series resistor feeding the rectifier. You can use a relay with an AC coil on a lower DC voltage. Just can't use it continuously this way.
The 60 Volts DC is what keys this one. Never have figured out why they did it this way.
Odds are that the 20uf 150-Volt electrolytic cap has died. This will reduce the voltage available.
I have seen the coil winding go bad on these, but not often.
I would check those two details first.
73
The 60 Volts DC is what keys this one. Never have figured out why they did it this way.
Odds are that the 20uf 150-Volt electrolytic cap has died. This will reduce the voltage available.
I have seen the coil winding go bad on these, but not often.
I would check those two details first.
73
nomadradio i found the problem and i just cannot believe I missed it right from the start. The amp had a 115v plug and cord on amplifier so i did not check if it was wired that inside. Amp was setup inside for 220v but had a 110v plug. I converted it to 110v and amp works great. Not a bad deal for the 150 dollars i paid for amp. It is a well learned lesson. Thanks
I see resistors across the coils of two of the relays in this skipper 300 that i am working on, and no diodes as are shown in the schematics.
what's the purpose of this?
EDT: with some thinking on it, i wonder if it's to provide a parallel path to ground for caps to discharge when the relay de-energizes so it doesn't all have to dissipate totally through the relay coil?
still wonder why there is no diode on two of them.
LC
what's the purpose of this?
EDT: with some thinking on it, i wonder if it's to provide a parallel path to ground for caps to discharge when the relay de-energizes so it doesn't all have to dissipate totally through the relay coil?
still wonder why there is no diode on two of them.
LC
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Easy way to tell. Unless yours is the late version with the relays on a circuit board against the rear panel.
The original version bolted each relay to the chassis with a couple of machine screws threaded into the relay's frame through holes in the plastic dust covers.
That version of the relay has been unavailable for decades. If they're held in with glue, they are not original.
73
The original version bolted each relay to the chassis with a couple of machine screws threaded into the relay's frame through holes in the plastic dust covers.
That version of the relay has been unavailable for decades. If they're held in with glue, they are not original.
73
ok that clinches it.
i have the old 6lf6 version with no PC boards.
only the relay that actually switches the RF (has coax connected to it, is original, and i believe it's the only one that had a diode on it. (dont have the amp in front of me right now).
the other two relays are smaller and upright and glued in.
they had the resistors on them.
i guess someone didn't have any diodes LOL.
thanks for that!
they sure did use a lot of different parts in these things. i have sandbar resistors in this one that aren't on either schematic.
ever have any luck tuning that recveive preamp "RFC" tunable inductor on the back panel?
LC
i have the old 6lf6 version with no PC boards.
only the relay that actually switches the RF (has coax connected to it, is original, and i believe it's the only one that had a diode on it. (dont have the amp in front of me right now).
the other two relays are smaller and upright and glued in.
they had the resistors on them.
i guess someone didn't have any diodes LOL.
thanks for that!
they sure did use a lot of different parts in these things. i have sandbar resistors in this one that aren't on either schematic.
ever have any luck tuning that recveive preamp "RFC" tunable inductor on the back panel?
LC