Unknown Device Identification

[LeapFrog]

Hello everyone, I recently went to a ham fest and bought this item.
I think it is a pre-amp, although I have no info on it.
[photo="medium"]4314[/photo] .
The little red wire has a spade terminalone end, a switch is seen on the unit, & on the opposite end an indicator led.
[photo="medium"]4315[/photo] .


I see two transistors, a small relay and some passive components, also a few coils.
Thank You.

-LeapFrog

 

[scout943]

Looks like some sort of high or low pass filter ??

 

[LeapFrog]

Looks like some sort of high or low pass filter ??

I was thinking the same thing until I noticed the transistors & relay, then I was thinking pre-amp, or a peripheral for an external meter?

 

[w9cll]

How in the hell did that get out of the lab????!!!???

 

[LeapFrog]

How in the hell did that get out of the lab????!!!???

Lol, really? I thought it had "made in China" written all over it.

 

[Tallman]

I believe that is used to key a linear. Not all radios have a direct key up signal line.
The incoming RF is used to trigger the relay which in turn keys the amp.
If it is a pre-amp it would not be very selective and amplify everything including noise.

 

[LeapFrog]

I believe that is used to key a linear. Not all radios have a direct key up signal line.
The incoming RF is used to trigger the relay which in turn keys the amp.

The red wire has me thinking you are correct! So it runs purely off of RF from what I see, if that's the case the voltage applied to the red wire would be minimal correct (just enough to trigger the internal relay on the amplifier)?

Unless the red wire is a V.cc / V.in line to power the unit?

 

[Tallman]

Lol, really? I thought it had "made in China" written all over it.

That's where his lab is!

 

[LeapFrog]

Lmao Tallman!

 

[Tallman]

The red wire has me thinking you are correct! So it runs purely off of RF from what I see, if that's the case the voltage applied to the red wire would be minimal correct (just enough to trigger the internal relay on the amplifier)?

Unless the red wire is a V.cc / V.in line to power the unit?

I did not see any electrolytic capacitors to filter DC power. To key certain amps you just take one side of the jack to ground.

 

[LeapFrog]

Well I get a solid 3.6mV on the red wire when I send some rf through this thing, the red l.e.d. never lit up, and I did not get continuity between ground and the wire..

 

[543_Dallas]

Seems too complicated to key an amplifier. That can be done with 1 transistor a diode and a 2 caps.

The switch on the front makes me think it could be a filter of some kind or a preamp. One transistor for amplification and the other as part of the RF sniffer to switch this thing out of line when you transmit. If it were a filter I can't see the need for 2 transistors .

 

[Robb]

Has a power wire to switch the relay once the sense line shifts the receive amp out of circuit when output RF is applied. The coils onboard are part of a filter to eliminate unnecessary freq amplification (outside of 11m?). Since the power wire is external, I'll guess that it require a 12v source.

More:
Black diode is a protection diode for the relay
Relay needs 12v
It should have a cap in there; I agree

 

[LeapFrog]

I might test this by applying a small current limited supply voltage with my variable psu, i may see the l.e.d. light!

 

[dave457]

How come you didn't ask what it was before you bought it?