[ARC5] [Milsurplus] Screen Bias in ARC-5 Transmitters

[J. Forster]

In CW, the VR tube is switched out, so the screen voltage will be much
higher...  probably 450 to 500 VDC.

-John

==============


> Hey John,
> I just got a T-19 going and I am running abt 500-550VDC, key down
> on the plates of the 1625s. I am running it on CW only and w/o
> scr/vfo regulation. I used the info from AB5S/W7EKB for the 'conversion'.
> They give info on a voltage divider that will give scr and vfo
> voltages within spec. Check their info for the recommended p/s specs.
> Can't rmbr just where my voltages were, but can check later if you
> need the info. My T-19 sounds good (to me) with only a slight chirp
> and very stable. I have no experience with the modulators or other
> accessories.
> GL and 73 de Bill K4JYS
>
> ----- Original Message -----
> From: "J. Forster" <jfor at quikus.com>
> To: ARC5 at mailman.QTH.net
> Cc: Milsurplus at mailman.QTH.net
> Sent: Thursday, October 24, 2013 7:59:50 PM
> Subject: [Milsurplus] Screen Bias in ARC-5 Transmitters
>
> Hi,
>
> I'm looking for confirmation of the approximate screen and plate voltages
> in ARC-5 transmitters and modulators.
>
> From the simplified Modulator diagram (Fig 4.2) it looks like the plates
> of the 1625s are at roughlt 550 VDC.
>
> The screen voltage seems to be roughly the drop across the VR-150-30
> (0D3) VR tube. (Actually, it looks to be about 56 VDC higher, due to the
> resistive divider.
>
> So, roughly, does 550 VDC on the plate and 200 VDC on the screen sound
> about right?
>
> -John
>
> ================
>
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