Ah yes!   I remember those things and think I even had one once.  I also 
had one made commercially back then too.  You could monitor cw and also 
AM as I recall, switching between the modes.  You still needed the wire 
for the antenna but it did have a built-in power supply.  Don't remember 
who made the thing anymore though.

Don  W6smb


On 9/11/2011 11:05 AM, Mike Duke, K5XU wrote:
> For those list members who read Bob Gunderson's Braille Technical
> Press, do you remember the advertisement for Grand Central Industries?
>
> One of the items this company sold was a brand of solid state gadgets
> such as very low power audio amplifiers, AM broadcast band part 15
> transmitters, etc. The manufacturer was Round Hill Industries.
>
> This was long before single chip circuits. These devices were
> assembled from individual components, and then fully sealed in epoxy,
> with bare wires protruding from the edges for connection to the power
> sourse, speakers, etc.
>
> They were literally the size of an ice cube, which for the late
> 1960's, was indeed minuscule. While I never confirmed it other than by
> hearsay, someone told me that the company did in fact use ice trays as
> the mold for the sealed units.
>
> One of the gadgets this company made was a "CW Monitor." The purpose
> of this monitor was to provide the side tone which we now take for
> granted, but which did not come with most rigs of the day, and was an
> add on option for only a few transceivers.
> You connected two wires to a small speaker, two others to a single D
> cell, and another to a few feet of hook up wire, which served as the
> antenna.
>
> Then, when you transmitted CW, the thing would squawk, thus giving you
> a means of monitoring what you were sending.
>
> Yesterday, I discovered a box of odds and ends left from the equipment
> of my late friend, K5ZFM.
>
> In the bottom of that box was one of the Round Hill CW Monitor
> modules, still attached to an old portable radio speaker and battery
> holder. I will clean it up and try it out later this week.
>
> The one that I bought on his advice as a Novice in 1969 gave up the
> ghost many years ago.
>
>
>
>
>
>
>
>
> Mike Duke, K5XU
> American Council of Blind Radio Amateurs
>