SCR-300 - BC-100 alignment indicator I-210-C restarted

[YLG80]

I've just bought an alignment indicator I-210-C for the BC-1000 on eBay.
It is interesting to note that this indicator was built by a German company, FunkTechnische Werke G.m.b.H (FTW logo) !

This little toy/gadget is really interesting because it allows to align the radio easily.
It's a very high impedance DVM with a funny magic eye tube 6E5/ VT-125.


Schematic:

There is a beautiful wartime period photo of a maintenance tech using that indicator to align a BC-1000 in 1944 in Fort Benning.

I've decided to use it again.
The power supply is easy to setup with a cheap power supply (16.00 €) circuit for Nixie tubes found on eBay.
It gives the exact necessary power outputs, 7.5V for filaments and 150V for the 6E5 tube HT.
That's an adjustable power supply that can be used with a Lead Acid 12V battery.

Circuit

Schematic:

Here is the indicator working as brand new device with the bright green magic eye that reminds me our radio when I was young.

Normally it should use a BA-39 (or a BA-80 or BA-70) battery like on the WII picture shown above, but it's almost impossible to find that battery to dissimulate the circuit in the battery housing.

The indicator I-210 is fully described in TM 11-315.

Yves

[Radtech]

The Dutch also made them for the British WS31.

[YLG80]

@ moderator: if possible could you add another zero to "BC-100" in the thread title? It's obviously BC-1000
Thanks

Yves

[Radtech]

The SCR-300 is the BC1000 so you don't really need the 1000 added.

[YLG80]

Yes that's true...

[SGM (ret)]

Yves,

I came across this old thread and was wondering how well this power supply is still working. Would you make any changes to the setup now that you've had it working for a while?

Thanks!

[YLG80]

Yves,

I came across this old thread and was wondering how well this power supply is still working. Would you make any changes to the setup now that you've had it working for a while?

Thanks!

Hello,
No, I would not change anything except the connector.
I have soldered a 807 valve socket as a connector with the inverter.

I have used the I-210-C recently with that power supply and it started as soon as I have connected the 12V to the inverter.
The only problem is to find that inverter here in Europe.
I have eventually found a seller on Aliexpress. Still waiting for the inverter.
It seems that you can still order it on Amazon.com in the U.S.
Yves

[Radtech]

These were made in Germany and Holland for the Dutch WS31 radios which were similar to the BC 1000.The first ones in 1948 were identical to the BC 1000 except for thre handset plug.The British were forced tp remove the relay circut due to a patent infringment law suit by Motorola.

[SGM (ret)]

Hello,
No, I would not change anything except the connector.
I have soldered a 807 valve socket as a connector with the inverter.

I have used the I-210-C recently with that power supply and it started as soon as I have connected the 12V to the inverter.
The only problem is to find that inverter here in Europe.
I have eventually found a seller on Aliexpress. Still waiting for the inverter.
It seems that you can still order it on Amazon.com in the U.S.
Yves

Thanks, Yves! I think I've tracked down an I-210-C alignment indicator here, so if I'm successful at buying it, I do fully intend to use the same type of inverter to run it. It looks like it will need some work, but as they say, "The right tool for the job" and all.

(You are also correct: Those inverters appear readily available on both eBay and Amazon.)

[YLG80]

Hello,
No, I would not change anything except the connector.
I have soldered a 807 valve socket as a connector with the inverter.

I have used the I-210-C recently with that power supply and it started as soon as I have connected the 12V to the inverter.
The only problem is to find that inverter here in Europe.
I have eventually found a seller on Aliexpress. Still waiting for the inverter.
It seems that you can still order it on Amazon.com in the U.S.
Yves

Thanks, Yves! I think I've tracked down an I-210-C alignment indicator here, so if I'm successful at buying it, I do fully intend to use the same type of inverter to run it. It looks like it will need some work, but as they say, "The right tool for the job" and all.

(You are also correct: Those inverters appear readily available on both eBay and Amazon.)

FYI, I have followed the TM 11-4024 exactly while using that indicator, and it makes the BC-1000 very easy to tune.
I have one alignment indicator made in Germany , and the other one made in USA.
Yves.

[SGM (ret)]

Good to know, Yves!

I have an I-210-C on the way, but it looks like I'll have to restore it first. Fortunately, the circuit schematic shows a pretty simple design that even a neophyte like me might be able to repair / restore. The 6E5 "magic eye" tube appears to be available from a number of vacuum tube suppliers, so even if that's bad I should be able to replace it.

I do have copies of the TM for the SCR-300, VRC-3 and the ME-40 Maintenance Equipment Set and have been studying the test and alignment instructions. It seems like a pretty straight forward process with the correct equipment. There are a lot of steps, but each one seems simple enough. (The VRC-3 instructions also cover how to use a multimeter to perform all of the same steps that the I-210-C is normally used for.)

I've also got a VO-6 oscillator in bound and will likely have to restore it, too. Again, the circuit schematic looks pretty simple. Power supply also looks possible with a DC-DC power step up unit that's readily available on both eBay and Amazon.

It all promises to be an interesting project. Hopefully, I won't screw anything up! LOL!

[YLG80]

Hi,
The 6E5 Magic eye is a rugged tube. I bet with you that it will work.
Adjust the little inverter filament voltage to 6.3V and the plate voltage between 125V and 250V if I remember well.
Typical 150V.
I had to restore the wires with the rubber insulation completely dry, and put some contact cleaner in the switch.
Then it was working right away.
Regards
Yves

[SGM (ret)]

Thanks for the information, Yves!

I think that I will have to do a bit more work to get mine to function. It is missing the 50 ohm slider pot and all of the test leads. However, it was the only one I could find for sale in the US. I've located several vendors with the sliding potentiometers and plan to use commonly available test leads to replace the missing ones.

I appreciate the identification of the connector! I'll start looking for one. It shouldn't be too hard to find.

[YLG80]

Thanks for the information, Yves!

I think that I will have to do a bit more work to get mine to function. It is missing the 50 ohm slider pot and all of the test leads. However, it was the only one I could find for sale in the US. I've located several vendors with the sliding potentiometers and plan to use commonly available test leads to replace the missing ones.

I appreciate the identification of the connector! I'll start looking for one. It shouldn't be too hard to find.

Hello,
I do not see any 50 Ohms pot on the schematic. There is only a 5 Kohms (could be also a 4k7).
Be sure to replace it with the correct value.
That is very easy to find.
Also very easy for you in the U.S, the 807 valve socket to be used as a Power Supply connector can be found here:
https://www.amazon.com/Cary-Ceramic-Soc ... B00KRI8UT8

Yves

[SGM (ret)]

My mistake - I was typing from memory rather than looking at the schematic or spec sheet.

The 5K linear potentiometer seems very prevalent (often called a "fader-slider"). The 807 socket also seems pretty easy to find.

At any rate, it looks like I'll have to rebuild the entre I-210, but that's OK. I'm looking forward to getting started.

As always, thanks for your suggestions and observations!