Lazarus rises from the dead, becomes a tube tester. SB1000

[Dmans]

Ray119,
See the attached manual for the AL-80B.

Page 12 and figure 5 in the manual should give you what you need.


73
David

 

[Shadetree Mechanic]

Can you tell me how you hooked up the primary side of this transformer. I'm trying to istall the same transformer into my SB-1000 and cannot fighure out the primary side for 240 volt.

Welcome Ray119!

 

[nomadradio]

This transformer uses a multi-tap "buck" winding. The point behind this was to make it match a wide range of line voltages, rather than just 120 and 240. As a result it's not just the typical setup with two 120-Volt primaries. If it was that simple, you would only need to parallel two pair of wires for 120 Volts, or wire them in series for 240.

I made notes of the hookup we used, but it results in a 240-Volt only setup. I don't think it will work on 120, but when we set it up I really didn't care.

I'll dig out the notes next time I'm at work. That stuff is on the 'airgapped' computer, no way to access it remotely from home.

73

 

[nomadradio]

So here is the hookup for 240 Volts only. No jumper wires are used on the barrier strip at all.

240-Volt only hookup, no jumpers are used on the barrier strip.
Tie strip term color
2 Brown
3 Black wire and orange wire
4 Brown-white stripe and gray plus one violet fan wire
5 Black/white stripe, fat black wire from relay and the other violet fan wire

The transformer's "buck" winding (orange and gray wires) takes the place of any jumpers that the old transformer used between points on the barrier strip.

I recommend hooking an AC voltmeter across the filament pins of the tube socket before you power it up this way. Should read 5 Volts AC plus or minus a quarter of a Volt. If it doesn't, the hookup has a problem.

73

 

[Ray119]

Thank you ;very much for this information and taking the time to dig it up for me.

 

[Wildcat444]

Hi Nomadradio,
I am very much interested to see your write up on this subject and I think it would benefit a great many!

The one remaining item on the modification wish list is to beef up protection for the meters. A current surge from a bad tube can damage either or both meters. A back-to-back pair of diodes will do the job as a rule, but I would rather have a 'sacrificial' 1/4-Watt resistor in line with each meter to serve as a fuse. This is still a work in progress. Ought to write up the rules for protecting analog meters this way.

Later.

73

 

[Bill K3HZP]

If you run into anymore of these. I have 2-3 of these brand new transformers.

Looking for a transformer for AL-80A amp.

 

[Bill K3HZP]

If you run into anymore of these. I have 2-3 of these brand new transformers.

Looking for a transformer for AL-80A amp Bill K3HZP.

If you run into anymore of these. I have 2-3 of these brand new transformers.

 

[nomadradio]

Can't believe I failed to mention the Ameritron/MFJ part number. That's where we get that transformer. Was a decent deal, last one I got. Been a while, though, so who knows what they get for it now.

Ameritron part number is 406-1109-2C

It is supplied with a big aluminum "L" bracket made from 1/8" sheet. It's to mount the transformer sideways. Won't fit in the original part's space bolted directly to the floor.

We move the circuit-board posts toward the front 3/4 of an inch or so and that way it will clear bolted flat to the floor. Not the same shape/size transformer core as the original. Bigger.

With any luck Ameritron still sells that one outright.

73