[Milsurplus] USS Slater DE-766

[Steven Syrotynski]

Hi Ken and Bill, thank you for your advice on this, i have an RAL-7 with 
it's power supply that i have yet to put in my shack, (must build larger 
house next time, :) ), i went to look at it and i see that switch. I 
will after a little cleaning fire up the one on the ship next weekend, 
sincere thanks for everyone's help and advice,
Steve


On 5/21/2020 4:36 PM, Kenneth G. Gordon wrote:
> On 21 May 2020 at 15:22, Steven Syrotynski wrote:
>
>> Hello out there, my name is Steven Syrotynski  W2TRH and i am one of the
>> volunteers in the radio room on the museum ship USS Slater here in
>> Albany  N.Y. We have some RAK,S and an RAL. One has a power supply that
>> is missing it's 80 Ohm snap in resistor that is next to that giant
>> ballast tube :), and the other one needs a power supply as well. Does
>> anyone have any of these around for sale, please let me know at
>> ssyrotyn at nycap.rr.com, below is a link to the ships web site, thank you
>> for your time,
>>
>> Steve
>>
>> https://ussslater.org/index.php
> As a long, long-time user of both the RAL and the RAK, I agree with Bill Cromwell, and can
> state categorically that you do NOT need the dropping resistor nor the ballast tube. In fact,
> the power supply has a switch down low, inside, which completely disconnects those. As I
> remember it, that switch is just under the heat-shield for the ballast tube or resistor.
>
> Using those causes a power drain of around 300 watts and much greater heat output.
> Without them, the power drain is less than 100 watts.
>
> You only need those if the receivers are being used on a combat ship, while that ship is in
> combat, with the turrets swinging around and other very heavy uses of the AC power.
>
> When using "shore power" you most certainly do not need them. Turn them off. The heat
> will be far less and the power supplies will last longer.
>
> As far as a power supply for the one missing, the power requirements for the RAL/RAK are
> very modest: there are only 6 tubes in either receiver. There is a plate on the front of each
> receiver which lists the power requirements.
>
> Temporarily, you can build a simple supply which will do the job. Normally, one needs 180
> VDC at 35 mA, 90 VDC regulated at 1 mA (!) and 6.2 V AC/DC at 2 amps. My home-built
> power supplies use a VR-90 for the regulated voltage, and those power supplies are far, far
> smaller, and at least as reliable as the original ones.
>
> The 90 V Regulated is for the regenertive detector to help prevent drift. In point of fact, the
> way the receiver is wired internally, you only need the filament voltage and 90 to 180 VDC
> input to the 180 VDC connection as internal resistors and wiring feed the detector if the 90
> V regulated is missing.
>
> The receivers are also designed specifically to run from a battery supply providing only
> filament voltage and 90 to 180 VDC.
>
> They are very, very good receivers, very stable, quite sensitive and unusually selective.
>
> I consider the RAL to be the finest HF TRF receiver I have ever used. An RAL-7 was my
> main station receiver for around 12 years, beginning in about 1960.
>
> Ken W7EKB