[Milsurplus] Question ( RBS; submarine )

[Richard]

Yes!  I have two RAL's, and when connected back-to-back I cannot hear 
one oscillating in the other, even at 23 Mc.  If a regenerative detector 
is set for vigorous oscillation radiation is no surprise, but it isn't 
used that way.  Guys that have tested couldn't hear it 20 feet from the 
antenna.

Richard, AA1P


On 08/24/2016 08:56 PM, Bill Cromwell wrote:
> Hi,
>
> I have a RAK-7 here and I tried using it with an LM to make tuning 
> charts. The LM (and every receiver I have) could not hear the RAK's 
> detector with oscillation cranked up! Inches away. Antenna wire 
> probing an opening in the  RAK's cabinet. Nothing. Nada. Zip point 
> s**t. The RAK, however could easily hear all the oscillators that are 
> in it's tuning range.
>
> 73,
>
> Bill  KU8H
>
> On 08/24/2016 02:14 PM, Kenneth G. Gordon wrote:
>> On 24 Aug 2016 at 7:38, Bill KA8VIT wrote:
>>
>>> It is my understanding that U.S. subs in WW2 used the RAL/RAKs because
>>> they are TRF radios and not superhets which emit a local oscillator
>>> signal onto the antenna which can be DFed when the receivers are in
>>> use.
>> Well, that is definitely, but only, true when receving an AM or MCW 
>> signal, since the
>> regenerative detector is in the non-oscillating condition for those 
>> modes.
>>
>> However, during WWII, all submarine comms were carried out via CW. In 
>> order for the
>> RAK/RAL to receive CW, the regenerative detector must be in the 
>> oscillating condition in
>> order for the operator to hear the CW signal.
>>
>> In fact, during the time that the regenie was being used by 
>> experimenters in the early days
>> of the broadcast industry, there was so much interference to other 
>> receivers from those
>> detectors that they were roundly hated. They were called "bloopers" 
>> and had no RF amp
>> between the detector and the antenna.
>>
>> The RAK/RAL (and other receivers somewhat like those) included at 
>> least one RF amp
>> stage in order to "decouple" the detector from the antenna. In the 
>> case of the RAK/RAL
>> there are two RF amp stages, the main purpose of which is isolation, 
>> not amplification.
>>
>> FYI, I used an RAL-7 as my main station receiver for at least 12 
>> years, so I am quite familiar
>> with the way it operates. I have at least one operational one now. I 
>> really like them.
>>
>> All of the above is yet another reason I am in agreement with Meir 
>> concerning DFing
>> receiver radiation: it didn't happen.
>>
>> One more thing: the RBO is a Scott receiver. It is a superhet and has 
>> an LO. The Scott
>> receivers of that time period were specifically designed to minimize 
>> the radiation from the
>> LO. Scott's model designations began with SLR for Super Low Radiation.
>>
>> For instance, the Scott designation for the Navy model RCH was SLR-F. 
>> Some RCHs still
>> had the SLR-F model name on their nomenclature plates. The RBO also 
>> had an SLR
>> designation. It may have been SLR-B, but I cannot remember now.
>>
>> The Navy specificed no more than 400 micro-micro-watts of LO 
>> radiation reaching the
>> antenna. All Scott receivers of the period easily met that 
>> specification. National had to add a
>> second RF amp stage to one of their "full-dial" receivers in order to 
>> meet it. That RF amp
>> stage was added to a special "porch" on the back of the receiver. I 
>> cannot remember the
>> model though.
>>
>> Ken W7EKB
>>