[Milsurplus] USN RBM vs. RBS Questions

Sat, 9 Aug 2003 21:09:49 -0700

Hi Hue and the group

A couple of comments about the RBM and probably the RBS as well, I never
fired up my RBS receiver, but did play with the RBM sets quite a bit.

First, selectivity.  The front panel switch should be labled broad and broader.

Second, I don't share Hue's comment about dial calibration.  Unlike some military
receivers of the era, like the BC-348 and BC-312, the RBM has adjustable oscillator
coils as well as trimmer capacitors.  About an hour of tweaking on my HF RBM brought
the calibration in remarkably well. Much better than any of my BC-348s. I do agree that
the dial tuning is too fast for comfortable ham use.

Third stability.  Not quite good enough for long term SSB monitoring, and prone
to mechanical instability, not quite as good as the BC-348s.  But then none of these radios
were ever designed for SSB operation.

One thing I did try was using the MF RBM as a Q5er for the HF RBM.  Worked good,
but the tuning range on the MF radios BFO is too limited to allow both USB and LSB
without tweaking the coil.

Lastly, anyone want some RBM and RBS receivers and RBM power supply? Available for
pickup only in Reno, Nevada.  They aren't in the best of condition, would need a lot of effort
for restoration., but could be used for general purpose listening.  They just don't fit into my
collecting needs, and I need the space.

Thanks

Jack

Jack Antonio WA7DIA
[email protected]

----- Original Message -----
From: "Hue Miller" <[email protected]>
To: <[email protected]>
Sent: Saturday, August 09, 2003 2:03 PM
Subject: Re: [Milsurplus] USN RBM vs. RBS Questions

> I have my doubts on how great this might have worked as an
> alert receiver. The calibration is not very good, and the dial tuning
> is much too fast. I suppose the wide band with the selectivity in
> that position took care of that. Also, i don't recall that the HF receiver is very stable either.
In
> its favor, Uncle Sam paid $1000
> WW2 dollars for each - a whole lot of money, and it looks good,
> nice architecture, very high quality construction, a smart circuit
> diagram, quality overall. It's just that the tuning is not very good.
> I suppose that's in keeping with how the military actually used
> most of their receivers....just set to frequency and dial locked.
> For actually using, for my money, the LF/MF receiver is much more usable.
> Hue Miller
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