D201A quirky fault: Goes "boop" on key up.
Oct 2, 2021 0:02:42 GMT -5
cbrown and holydvr1776 like this
Post by 2600 on Oct 2, 2021 0:02:42 GMT -5
Here's an odd quirk of the Tram D201A base radio. The older 23-channel radio doesn't seem to do this. When you key the mike a short "boop" is heard on the radio's modulation. Turning the receiver volume down will make it louder. In some radios, just turning up the volume control will stop it.
Got tired of this, and came up with a hack. Takes two resistors and a generic NPN transistor. We used a 2N2222, or PN2222A. A 3N3904, 2N4400, and hundreds of others will work.
The transistor's emitter goes to the clockwise lug of the squelch control. Has a black ground wire on it. The collector goes to the opposite end of the control. The base lead gets bent around away from the control.
A 5.6k ( or 4.7k, or 10k) resistor goes from the ground lug of the control to the base lead of the transistor. Another resistor in the range mentioned laps onto the transistor base lead.
The far end of this second resistor gets a wire lap-solderd to the end. Has to be long enough to reach the inboard-most lug of the tie strip behind the squelch control. This is the lug nearest the mode selector switch. Should have a violet wire already on it.
This has the effect of closing the squelch as soon as you key the mike. Shuts off the feedback path from receiver to transmitter that created the quirk. Not a fix, just a patch.
But a patch that has worked every time, so far for cheap.
73
Got tired of this, and came up with a hack. Takes two resistors and a generic NPN transistor. We used a 2N2222, or PN2222A. A 3N3904, 2N4400, and hundreds of others will work.
The transistor's emitter goes to the clockwise lug of the squelch control. Has a black ground wire on it. The collector goes to the opposite end of the control. The base lead gets bent around away from the control.
A 5.6k ( or 4.7k, or 10k) resistor goes from the ground lug of the control to the base lead of the transistor. Another resistor in the range mentioned laps onto the transistor base lead.
The far end of this second resistor gets a wire lap-solderd to the end. Has to be long enough to reach the inboard-most lug of the tie strip behind the squelch control. This is the lug nearest the mode selector switch. Should have a violet wire already on it.
This has the effect of closing the squelch as soon as you key the mike. Shuts off the feedback path from receiver to transmitter that created the quirk. Not a fix, just a patch.
But a patch that has worked every time, so far for cheap.
73
