[Milsurplus] RAK-7

[Richard]

I measure 25 ma at 180 volts from a regulated supply to the RAK, with no 
VR tube.   Further, there is a resistor from 180 volts to the 90 volt 
input, so if you're using a regulated supply you don't need the dropping 
resistor and VR tube.  They put about 30 ma through the VR tube to 
regulate a half milliampere  load, which is absurd.  160 to 180 volts 
seems to be the sweet spot. Above 180 volts it's too hot, and below it 
slowly goes to sleep, but at 90 volts it's still very usable.

The ac-dc switch is double pole single throw shunted with removable 
links.  The IB says don't open the switch with the links open because 
the ac supply is disconnected and may be damaged.  The book mentions dc 
operation with a 6 volt battery and 180 volt B battery, but there is no 
discussion how to do it.  You would have to make connections to the load 
side of the open links as there are no battery input points, and 
remember to keep the switch closed for ac operation.  Apparently it was 
a rare occasion...  So, use the regular input points for ac or battery 
operation, but not both at the same time.

Richard, AA1P

On 07/23/2016 06:09 PM, Michael Bittner wrote:
> I've read on these lists that some RAK-7 owners are running them on 90 
> Volts B+ from batteries.  I assume that, when this is done, the 90 
> Volts is connected to the 180-Volt input on the RAK and that the 
> 90-Volt input is left floating.  Is this correct?
> Also, some have suggested simple AC power supplies for the RAK.  I 
> have a simple regulated power supply that can provide the 180 Volts.  
> I'm assuming that its connection to the RAK's should be the same as 
> for battery operation above - correct?
> By adding up the RAK's plate and screen currents listed in the manual, 
> I get 24 mA.  Is this current about right for a small power supply 
> substituting for the original monster power supply, or does it need to 
> be more?  None of the resistors and VR tube between 180 volts and 90 
> Volts in the original power supply will be in the circuit.
> Mike, W6MAB
>
>
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