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Motorola R2001-series CRT Filament Voltage

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kcbooboo
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Motorola R2001-series CRT Filament Voltage

Postby kcbooboo » Tue Aug 16, 2016 2:23 pm

Does anyone know the EXACT filament voltage the CRTs are designed for? I've seen tubes that want 6.0, others want 6.2, others want 6.3. Yes, I know it's "6V nominal" but I'm looking for the exact voltage specification. Mine was getting 6.2VRMS until I raised the HV to what it's supposed to be. Measuring it is not an easy feat either, with about -2,000VDC riding on the filament wires.

The filament voltage is developed by the HVPS transformer, so if you change the HV, the filament voltage follows.

If someone has access to, or can point me to a data sheet for the tube that has that info, that would be great. AEG-Telefunken made my CRT but so far I haven't found any recognizable number except the Motorola part number, which is slightly different from what's shown in the various manuals.

Thanks.

Bob M.

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Re: Motorola R2001-series CRT Filament Voltage

Postby DJP126 » Wed Aug 17, 2016 1:08 pm

Per the R2001A maintainence manual, the filament is 6.3 VAC. As the same tube was used in all models, it should be the same for all.
Dave

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Re: Motorola R2001-series CRT Filament Voltage

Postby kcbooboo » Wed Aug 17, 2016 1:56 pm

Perfect. I hadn't seen that and I have a very old "A" manual. When my cathode voltage was -1930V I had 6.20Vrms on the filament. I have since raised the HV to -2000V so the filament should have gone up about 3.5% to 6.42Vrms. I didn't want to stress things too much.

There was a question I wanted to ask you about my R2001B but darned if I can remember what it is now. I had sent you a couple of PMs but it seems you never received them. If I remember I'll post it here.

Thanks.

Bob M.

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Re: Motorola R2001-series CRT Filament Voltage

Postby kcbooboo » Thu Aug 18, 2016 4:27 am

I took a look at the service manuals. That 6.3V value is present in all of them, in the HVPS description. I have a feeling that this is a "nominal" voltage, and may or may not be what the tube itself has as a specification. There may not be any publicly available spec.

I might be able to find out more if I could find an industry-standard number on the tube. There are several numbers printed in ink that are obviously Motorola part numbers, and some stamped numbers on a white label that are most likely mfgr numbers and a date code, but nothing seems to stand out. Of course, if there was a standard number, people would have bought those instead of having to rely on Motorola Parts.

Bob M.

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Re: Motorola R2001-series CRT Filament Voltage

Postby kcbooboo » Fri Aug 19, 2016 11:19 am

Dave: I remembered the questions I wanted to ask you.

1. My R2001B constantly sounds the alarm beep in Wideband monitor mode as soon as the squelch opens. The deviation alarm is set to 99.9 kHz. I tried setting it to 00.0 kHz and that makes it sound all the time. I can't seem to turn it off completely. Am I doing something wrong?

2. I noticed that the R2001D has some special documented functions that can be set from the keypad. Do these also work on the "A", "B", or "C", or was this only available on the "D"?

Thanks.

Bob M.

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Re: Motorola R2001-series CRT Filament Voltage

Postby DJP126 » Tue Aug 30, 2016 11:41 am

kcbooboo wrote:Dave: I remembered the questions I wanted to ask you.

1. My R2001B constantly sounds the alarm beep in Wideband monitor mode as soon as the squelch opens. The deviation alarm is set to 99.9 kHz. I tried setting it to 00.0 kHz and that makes it sound all the time. I can't seem to turn it off completely. Am I doing something wrong?

2. I noticed that the R2001D has some special documented functions that can be set from the keypad. Do these also work on the "A", "B", or "C", or was this only available on the "D"?

Thanks.

Bob M.


Hi Bob, The over dev alarm can not be turned off in the "A" or "B" versions. All you can do is set the squelch to threshold to eliminate the white noise or switch to narrow band. The special function codes are only in the "D" models.
Dave

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Re: Motorola R2001-series CRT Filament Voltage

Postby kcbooboo » Fri Sep 02, 2016 4:21 pm

Thank you.

Bob M.


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