[MRCA] BC-611 Operational Question

Thu Oct 3 08:53:21 EDT 2024

Here is a map of the training exercise we did in anticipation of the
LST-325 transit of Buzzards Bay.

K2WI, that's me, was running a TBX set with 24-foot vertical.

W1NZR switched to BC-611 after initial contact with a larger rig, and we
were able to communicate.  I copied him about 3 by 3.    W1NZR with BC-611
to K2WI with TBX 13 miles of salt water from a beachfront location.

I believe during the transit, before he switched to the BC-611 on the deck,
Perry on WW2LST was running the TCS and his signal would be best described
as "blistering" from the mouth of the bay.

The other picture is my typical setup which also included the gasoline
generator during the Buzzards Bay exercises.

73, RF

On Thu, Oct 3, 2024 at 8:00 AM MARK DORNEY via MRCA <mrca at mailman.qth.net>
wrote:

>          What frequency was the BC-611 set on?  Also, on a good
> propagation day, good things happen communication wise. 1-3 miles ( the
> distance between your shore station and the LST), when traveling in a slow
> transport/supply plane like a C-47, flying between 150-200 mph, gives about
> 4-5 minutes of comms capability to and from the aircraft. An LST moves at
> maybe 25 mph ( I’m not going to convert knots into mph) max . Much smaller
> communications window for the aircraft than the ship ( the aircraft is
> moving much faster than the ship), and your shore station was using a less
> powerful radio than the ship or the aircraft,  and using a far less
> efficient antenna. And the question wouldn’t be so much “can the ship reach
> your station on shore” - the ships radio has a pretty powerful
> transmitter,, a long antenna and the hull of the ship is one big
> counterpoise. The question would be more “ can your shore station radio
> reach the ship”.
>
> 73
> Mark D.
> WW2RDO
>
> “In matters of style, float with the current. In matters of Principle,
> stand like a rock. “.   -   Thomas Jefferson
>
> Sent from my iPhone
>
> On Oct 3, 2024, at 12:41 AM, Christopher Bowne <aj1g at sbcglobal.net> wrote:
>
> When LST-325 was coming up Buzzards Bay enroute to a port call at
> Massachusetts Maritime Academy during an East Coast cruise in 2005, a
> number of us had a field exercise where we set up portable stations on
> shore along the bay and contacted the  ship on 75 meter AM. Perry, W8AU
> contacted us not only with the main original main HF transmitter, a TCK if
> I recall correctly, from the radio room, but also, when the ship was within
> line of sight between 1 and 3 miles away, from the bridge with a BC-611
> walkie talkie and also visually via Morse lamp. There were several of us
> operating from the beach. Rob Flory and I were on a beach just south of the
> MMA, I was running a GRC-9 powered with
> a DY-88 dynamotor and a 12v car battery. .Rob was on a Marine TBX.  My
> GRC-9 used about a 12 foot field whip antenna and a number of on sand
> counter poise wires.  I believe Rob used a similar antenna.  I remember
> that the signal from Perry’s 611
> was loud and clear, when ship was well over a mille out across the bay.
>
> I would think it likely that comms between aircraft command sets  and
> ground troops below with BC-611s were common such as when coordinating
> parachute supply drops if there were no other more powerful sets on the
> ground to  communicate with were available.
>
> I believe that there was a BC-611 variant that was installed  in gliders
> for communication with their tow planes.
>
> 73 de Chris AJ1G
> Stonington CT
>
>
>
>
> Sent from my iPhone
>
> On Oct 2, 2024, at 19:50, Mark K3MSB <mark.k3msb at gmail.com> wrote:
>
> 
> I was not even remotely implying that my SCR-274N used in the feld was
> authentic.   Clearly it is not.    I would be taking it into the field (in
> a tent) to show (demo) a working WW II USAAF Radio Set.   It will be
> explained that it was an airborne system used on Allied aircraft.   They
> will have a small 117 generator available for powering the power supply I
> bring along (which is my 28V power supply with two tractor batteries
> floated across the output).    I of course will not be demoing it all the
> time;  in the off times I suggested that just the two batteries could power
> the Navigation receiver (0.19 to 0.55) tuned to a beacon.   Still in the
> early planning stages.....
>
> Mark K3MSB
>
>
>
>
>
>
>
>
>
>
>
> On Wed, Oct 2, 2024 at 7:14 PM MARK DORNEY via MRCA <mrca at mailman.qth.net>
> wrote:
>
>>     About the only time an SRC-274-N would have been mobile would have
>> been if the set was mounted in an aircraft. The SCR-274-N wasn’t really
>> designed for use on the ground in the field. The set isn’t rugged enough to
>> really withstand the rigors of field use and is not sealed against
>> weather.  Power supply would also have been a problem since 24 volt vehicle
>> electrical systems ( required to power up an SCR-274-N ) didn’t really come
>> into use with US Army Ground Forces until the Korean War. During WW2, radio
>> equipped vehicles had mostly 12 volt power systems ( 6 volt could be used ,
>> but there were problems keeping a 6 volt equipped radio vehicle’s battery
>> charged in the field ).  There were very limited 12 volt versions of the
>> SRC-274 type radios, but they were very few and far between, and by the
>> beginning of 1943, the USAAF had converted almost all of their aircraft (
>> and all of their new aircraft ) to operate using 24 volt electrical
>> systems, 12 volt aircraft liaison sets simply were no longer supplied to
>> the USAAF overseas (the USN converted their aircraft sooner ). Another
>> problem you might encounter using these few 12 volt powered aircraft radio
>> systems is the limited frequency range the early radios used. You may not
>> find a transmitter with a frequency range legal for you to use. Of the USN
>> radios, the Western Electric GF-11/RU-16 is a 12 volt radio that comes to
>> mind, but that set, while designed as an aircraft radio, wasn’t really
>> fielded as an aircraft radio ( only documented use was on USMC ships - I
>> didn’t know the Marines had ships, and by one USMC Artillery Battalion on a
>> motor gun carriage). now I suppose a scavenged aircraft APU could be used
>> to power your SCR-274-N, but as far as any standard vehicle was concerned,
>> the options would have been very limited. Scavenged liaison radios like
>> your SCR-274-N could be found in airfield watch stations, but were powered
>> either using a rectifier ( if that could be found) or much more commonly a
>> battery bank of scavenged automobile batteries.
>>
>> 73
>> Mark D.
>> WW2RDO
>>
>> “In matters of style, float with the current. In matters of Principle,
>> stand like a rock. “.   -   Thomas Jefferson
>>
>> Sent from my iPhone
>>
>> On Oct 2, 2024, at 6:00 PM, MARK DORNEY via MRCA <mrca at mailman.qth.net>
>> wrote:
>>
>> efficient on the 60 meters ( the short antenna on the BC-611 is better
>> suited to that frequency band ). Unfortunately, the bandwidth the
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