[MRCA] 1155

[J. Forster]

> On 7/7/2012 12:15 PM, J. Forster wrote:
>
> Neither the BC-348 nor the ART-13 was available at the start of WW II.
>
> Not so sure about that concerning the  -348. I have a BC-224-B which
> has a contract date of 5 January 1939. My -348-C has a contract date
> of 1941. At least the 348 was available very early in the war, and
> certainly predates the AN/ART-13.

The war did not start on Dec 7 1941, but when Hitler marched into Poland.

>> OK, the SCR-522 was a POS. At the time it was introduced, what was
>> better?
>>
>> -John
>
> After collecting and firing up an SCR-522, I feel it is actually a
> decent set, given the technology of the time. Certainly better than the
> WE-233A (AN/ARC-4).

I never said it was a POS. I was quoting an earlier post, trying to make
the point that the relevant question is whether it is better than the 
other options.


> However, the SCR-522 has some rather interesting design "features", it
> is not a simple set to troubleshoot.  I don't know if these
> "features" were a result of its British legacy, or Bendix, who
> seemed to be fond of rather convoluted control schemes.

I think it was pretty much cloned from a British design, like the WS 19.

> First was the regulated 13V filament voltage, in both the 12 and 24
> volt versions.  The dynamotor provided the filament voltage, and had
> a carbon pile regulating the field current.

So did the R.1155. The dyno had a series regulator controlled by the
unobtainable "Londex" relay. The dyno was about 10 V and would work over a
wide input range.


> Indeed I have read
> that the original dynamotor supplies were maintenance dogs and had
> to be redesigned.  The regulated filament voltage never appeared on
> later WWII VHF radios.

OK. I know the T.1154 dynos were troublesome, but they were very high
voltage machines. The HV commutators blew over at altitude, I think.

> Second was a PTT scheme that had a relay drop out for transmit and
> energized for receive.  The entire PTT scheme involved multiple relays
> and is not a straightforward thing to trace. To me, it seemed to
> be overcomplicated, and I've wondered what the design goals were
> that warranted it.
>
> Jack Antonio WA7DIA/4

The sets were designed in a hurried run-up to WW II, in a country with far
fewer resources than the US, and built in factories and by people being
bombed daily. IMO, they did pretty well.

Best,

-John

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