BC-1060A oscilloscope

[kb3ouk]

does anyone have a manual for a BC-1060A scope, or know anything about one, like how to use it? I got one today, looks like at the moment the only thing wrong is the power switch is gone, have to put a new toggle switch in its place.

[WA3VJB]

That's an oldie !

Let's hope the power switch will be the only problem.

Main concern is whether the scope display tube has any life in it. Them phosphors get tired.
Next concern would be the power supply caps.
Farther down the list will be the support circuitry for deflection and time base.

Found a schematic.
http://www.mcmlv.org/Archive/Military/BC-1060A.pdf

And some photos:
http://www.radiomuseum.org/r/waterman_oscilloscope_bc_1060_a.html


What do you plan to use it for ?  Part of your bench test equipment?  Waveform monitor?

If it's for your on-air signal, to determine whether you're fully modulating and whether the audio going in looks like it's supposed to coming out, you'll need to figure out whether the scope has enough bandwidth to carry you to the frequency of your carrier. 160m should be easy, but old scopes like this sometimes run out around 4mc.  Might still be a good display piece to see the output of your audio console, and not try to use it to see the carrier.

I'd also like to draw your attention to the Estate Sale of K3ZRF.
He has several scopes you could consider for on-air waveform monitoring.
Not far from you to see, buy and take with you.
There's a link in the For Sale section with details for those interested to respond.

[kb3ouk]

well, at the moment i'm just hoping it will work. maybe if i can figure out what the signal corps used it for, that will help me decide what i will do with it. I already found the schematic, actually the link you posted is the same exact site i found. if i do use it to monitor my signal, if it cuts off at 4 mc that will be alright since i don't go any higher than that anyway.

[kb3ouk]

i also will say that this one isn't a Waterman, it was built by the Caroled Co., Inc. according to the data tag. here's a pic of mine, it's in good shape.

[WA3VJB]

You may have notice the acceptance stamp -- orange paint -- June 1953.

I haven't been able to find a specification sheet. You're probably doing the same search. Good luck.  
The 30K on the frequency sweep suggests it's for audio, not RF.

Good looking old buzzard scope.  Be careful firing it up when you put a new switch in there.

[kb3ouk]

i got the switch in and turned it on, no problems there, but once it warmed up, i noticed there was nothing coming from the CRT. looked in the back, and sure enough, no glow coming from that end either.

[kb3ouk]

schematic says it takes a 3GP1 CRT. here's what the army signal museum has about this scope:

BC-1060*    Oscilloscope, 3GP1 CRT, P/O RC-283 IFF SET; TM 11-22526,1944   

[W7TFO]

i noticed there was nothing coming from the CRT. looked in the back, and sure enough, no glow coming from that end either.

Check for filament Voltage at the pins first.  If it OK, there are a lot of tubes available, both on eBay and from regular sellers.  A lot of 3" tubes are basically the same so you ought to have no problem finding one.

73DG

[kb3ouk]

I'll try the filament voltage, which is gonna require two people to do, on the chassis at the back there is a switch that when the chassis is in the case, it is pushed in. so while i am checking the voltage, i'll have to have someone else hold that switch in. that will have to wait till tomorrow.

[W7TFO]

If you get it percolating, why not try the direct hook-up feeding H&V inputs for a trapezoid display?

The actual BW of the scope doesn't matter that way.

It is a lot easier to determine actual mod levels that way.

73DG

[kb3ouk]

ok, how do you do the trapezoid hookup? i could look it up in my '53 arrl handbook, but i don't have that with me. that' the one that combines the audio and rf input to make the trapezoid, right? i might be able to manage that with my ft-901dm, it may not be the best but if i can pick up enough rf and get an audio sample from the rig it might work, i'll try getting the audio from it, it has a switch in the front to switch the mic audio to the speakers as a sort of monitor, i'll see about using that. now if i get this thing running i can finish the rest of the projuects that have been accumulating here, need to really do the mods to the 901 to get the audio (rx and tx) sounding better, and then to replace some micas in the linear to get it to run better. and one more thing, paul said that he thinks it may be an audio scope, will that matter for the trapezoidal mod monitor setup? or does it still need to be able to do rf for that?

[W7TFO]

If you are using the H&V plate inputs, the sweep speed and input BW doesn't apply, as it is out of the circuit completely.

You would feed an audio sample from the modulator output, and an RF sample from the transmitter output.  Very small voltages are needed for this, but they have to be from the right places.

73DG

[kb3ouk]

ok, i think i can figure out how to do that for this scope, i'll have to set the switches so the H and V are direct to plate, not through the amplifiers. the only thing i'm gonna have to figure out then is how to get the rf sample off the 901, i can easily get the audio sample by switching the one switch to monitor then taking it off the headphone jack( that way the speaker still works), but the rf i have to think how to get a good sample from that. how could I do that? i don't think wrapping a wire around the coax a bunch of times would pick up enough to work, or would it?

[W7TFO]

The mod sample must come from the point where the modulator hits the final, not just any audio will do due to non-linearities in the preamps & drivers.  If it is a plate-modulated tube rig, use care and sample the high end of the mod trans secondary, thru a .001 cap rated high enough voltage to stand the gaff.  Load it with a 10K pot, wiper to your scope.

The simplest way to get an RF sample is a small value cap to maybe 10K to ground, right at the RF output jack.

The best way to get an accurate RF sample is to use a simple choke, wound with maybe 100 turns on a 1" form across the output.  use a slider on the choke for adjustment into the scope.

73DG

[KA2DZT]

The filament in the CRT may be OK, check the solder on the pins of the CRT.  Try resoldering the filament pins if you have filament voltage at the socket.

Fred

[kb3ouk]

ok i checked the voltage at the socket, 6.3 volts like it should have. now, how exactly does the socket come off of the CRT?

[W7TFO]

Just like any regular tube, pull straight off, a little wiggle maybe.  Hold the tube base at the same time in case it is a bit loose.

73DG

[kb3ouk]

ok, i tried that but didn't want to do it too hard for fear of breaking something.

[W7TFO]

11 pins can make it tough.

73DG

[kb3ouk]

yea, i'm glad they numbered them, couldn't find the keyway at first. one thing i still don't seem to understand hwy they designed it the way they did is the way the ac line is hooked to the transformer. they put one side of the directly to the transformer. the other side goees like this:

power cord -> fuse -> safety switch -> power switch -> transformer

now where do you suppose those components are on the chassis? the power cord and the safety switch are on the rear. the fuse holder and power switch are on the front panel. the iron is in the rear compartment. so the incoming ac power has to go the whole way to the front to go through the fuse, then to the back to go through the safety switch, then back to front through the power switch, then back to the transformer. now, the safety switch has to be in the back, since it closes when the chassis is slid the whole way back in the case. but why to make the hole where the cord comes through larger so the fuse can be put in the back? i guess they were more concerned over ease of changing the fuse than figuring out the internal wiring.

[kb3ouk]

ok finally got a new crt for this scope. now, what would be something simple i can do to test to see if it works, at least the crt filaments light up this time, but i want to check to see if the rest of the scope works.