[Amps] SCR to adjust 240v to 200v

[Jim Durham]

My real reason for asking was not whether the SCR would work to vary the 
voltage, that's done all the time, but it does put spikes in the AC 
waveform.  I'm sure Henry never anticipated such and how the choke and 
filter cap in the power supply would love that (or not).

Thanks,

73 de Jim W2XO


On 08/12/2016 03:41 PM, Michael Clarson wrote:
> Jim: Motorola did something like you describe in their "MOTRAC" series 
> base stations (beige cabinets) in the 1960s and 70s. These were 
> 250-350 watt output stations using a pair of 8560s as finals. They 
> regulated B+ with SCRs in the transformer primary. All done at 60 Hz 
> and never had any RFI issues from these supplies. I do not have any 
> manuals. Later versions of these stations used constant voltage 
> transformers. Good luck finding a solution. --73, Mike, wv2zow
>
> On Fri, Aug 12, 2016 at 1:07 PM, Jim Durham <jimdur at gmail.com 
> <mailto:jimdur at gmail.com>> wrote:
>
>     Hello all,
>
>     This is my first posting, so Howdy..
>
>     I have a Henry 2k-2 (modified to take 3-500Zs).  After I bought
>     it, some years back, I fired it up and tube filaments were very
>     bright and HV was high.
>
>     Talked to Henry. They asked me the plate transformer number, which
>     they looked up and said "Oh, that's the 200v European
>     transformer". So, I put a hefty variac on the 240v AC incoming and
>     all is fine, except I'd like to ditch the variac and was wondering
>     about if anyone on here had any wise words about using an SCR
>     instead to back the AC voltage off.
>
>     My experience with big SCRs (TV studio lighting) was that they
>     tend to  put out a lot of RF hash.  I also wonder about how the
>     choke and filter cap in the power supply would like non-sinusoidal
>     AC waveform?
>
>     Anyone have any experience with this?
>
>     Thanks and 73,
>
>     Jim, W2XO
>
>
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