[Milsurplus] RBC

[Kenneth G. Gordon]

>     somewhere. I wonder if a limiting factor is the 6SK7 in the RF stage.

I have here a BC-454 which was "converted" to cover 10 meters back in 
about 1956 or so. My measurements of the sensitivitiy of this restored 
receiver on 10 meters with my HP-8640B proves sensitivity of less than 1 
microvolt MDS on AM, and even better on CW.

Substituting a 12SG7, lower noise tube for the 12SK7 resulted in less noise, 
but no apparent improvement in sensitivity over the 12SK7.

I was not only amazed, but very pleased. I think RCA knew very well what 
they were doing when using the 6/12SK7.

> Maybe
>     a cascode plug-in adapter would help; maybe not.

I sincerely doubt it would make enough of a difference to warrant the work.

> I am VERY impressed by a
>     receiver having a 5-gang tuning capacitor with 4 tuned stages ahead of the
>     mixer. Amazing. Never seen such on any other receive i am familiar with. 
>     But the limiting factor for me is unfortunately, the size. I´d have to
>     look around for several other boxes to jettison to be able to have an RBC,
>     and then if really liked it, i´d have to have at least another. However,
>     after checking out the manual, i´ll definitely take a longer look at the
>     next one i see at the hamfests. -Hue

Well, I consider the RBB/RBC series about the best of the WWII era 
receivers. 

One added very, very effective circuit in those receivers is about the best 
audio limiter I have ever used.

At one time, I used an RBB receiver and a TechRad T-350XM transmitter as 
my main station equipment operating full-QSK CW with separate antennas in 
relatively close proximity: my own station signal was never any louder in my 
headphones than the station I was tuned to copy. The TechRad has a pair of 
813s in the final stage and the output power is well over 500 watts at 1 KW 
input.

A fellow ham (SK) came into my shack once when I was operating in a CW 
traffic-net and was amazed at what he heard: no difference in signal levels 
between my local KW and the station I was copying, who was about S-6.

Ken W7EKB



Kenneth G. Gordon W7EKB

"Courage is being scared to death but saddling up anyway."--- John   Wayne