Gray g300 Blown Resistor

sweepersrgr8 · May 25, 2020

Anyone out there with an old Gray 300, that can tell me the value of this blown resistor to the left of the relay?

999 · May 25, 2020

Based on the 150 schematic my guess would be a 470 ohm in the keying transistor circuit.

nomadradio · May 25, 2020

I think this board's keying circuit is at the opposite end of the board. Pretty sure the burned resistor is in the preamp circuit. My educated guess would be 470 ohms. Good chance that the PN2907A preamp transistor is also toast.

73

sweepersrgr8 · May 30, 2020

Thanks Nomad/999. Yeah, I knew it started with a 4, but that leaves a lot of guess work. If that works, I'm going to try to document this unit on CBTRICKS. There is no info on the internet for this amp, and seems like there are alot of questions about them.

nomadradio · May 30, 2020

It looks as if someone started out with the often-copied "TNT" relay circuit board layout, but altered it to use a cheap DIP relay for the RF power side. The rating of 1 Amp printed on it really doesn't sound big enough to me. The pinout appears to be the same as the 3-Amp type "D2N" relay we use to replace the old Potter and Brumfield R50. Would be a stouter choice in the long run.

73

sweepersrgr8 · Jun 3, 2020

nomadradio said:
It looks as if someone started out with the often-copied "TNT" relay circuit board layout, but altered it to use a cheap DIP relay for the RF power side. The rating of 1 Amp printed on it really doesn't sound big enough to me. The pinout appears to be the same as the 3-Amp type "D2N" relay we use to replace the old Potter and Brumfield R50. Would be a stouter choice in the long run.

73

Absolutely my first upgrade, after I get it working properly.

Search

Gray g300 Blown Resistor

sweepersrgr8

Member

999

Sr. Member

nomadradio

Analog Retentive

sweepersrgr8

Member

nomadradio

Analog Retentive

sweepersrgr8

Member

Settings Notifications

Options