What is this mystery test tool from ancient times???

[KJ4OLL]

Hi,
I had a problem with one of my receivers, could not find the cause easily.
Turned out to be a bad tube.
(Did not know the 9 pin “socket saver” on my TV-10 tester was intermittent at that time.)
Anyway, baffled, I took the receiver in to a friend @ work who maintains the Motorola trunked public safety equipment.

Old time Elmer, powered up the receiver, put a speaker on it, the touched the grids & plate pins on the tubes in the RF section with this “thing” to hear the resulting signal on the speaker.

Said he has had the tool since the 1960’s, when they were common.
I want one!
It has no markings on it, just puts out a waveform of some type from the tip of the probe, really makes this type of troubleshooting simple.

I need simple.
I can’t figure out what name/description to search for .
I do know it is not this: http://qrpkits.com/tracerinjector.html
Ideas???
73
Frank
KJ4OLL

[kg7bz]

That looks like the EICO Signal Injector Probe, seen about halfway down on this page:

http://www.antiqueradios.com/forums/viewtopic.php?t=109446

Schematic included on the page

[Opcom]

There was an old kind that was like a mini buzzer.

[W7TFO]

Those were sold as the "Mosquito".

I still have one around here somewheres.

All electronic, no mechanical buzzer.

Uses AA cell.

73DG

[WBear2GCR]

Dennis, yours is a Don Bosco "Mosquito".
That one is the Eico.

If you want to, I would like to own a Don Bosco Mosquito.
Been looking for one for a long time!

My mentor in ham radio, Bob Barkey W2UO (sk) had one, and it is FB for troubleshooting
RF & audio boatanchor stuff!

The circuit for the Mosquito was never published, but I think it is/was a "blocking oscillator, with the "coil" out near the tip, which accounted for its ability to "broadcast" to nearby grids without touching.

Popular Electronics or Radio Electronics had an article back in the 60s for something called the "Tracex" which I built back in the day. It did not have the coil and the same effect, but had the benefit of connecting a crystal earphone to it to listen, pull the plug and it was an injector.

Can post the schematic of that if anyone is interested.

                   _-_-bear

[KJ4OLL]

Thanks very much for all the info!
The EICO is what my Elmer has, and we found lots of info on the web about it.

[W1RKW]

There's also this: http://www.radiomuseum.org/r/ctr_signal_injector_se_250c.html

[WQ9E]

I got lucky and found a boxed set on ebay that contained the Don Bosco Stethotracer and Mosquito with the accessory probes, etc.  They are useful little devices.  More info on them can be found on the web here:  http://www.stevenjohnson.com/donbosco.htm

[flintstone mop]

it made things very easy, back in the day.