Amplifier questions

[TonyV225]

I have a solidstate base amplifier here and I have no clue who makes it. It says GB 300 SOLIDSTATE Three Hundred Bi Linear. I has a 4 position power selector 3 rocker swtches preamp, am/ssb, power on/off The unit is a good size heavy and is black with red lettering the 4 power transistors are MRF-492 I may have to look again its been awhile.

There is a problem with it if I remember right the SWR was sky high on all power settings is it out of tune or where do I look?? Bad cap something on the input side?? Ide like to get this working Thanks .....Tony

 

[Robb]

Got pics?

 

[TonyV225]

ill have to one if need be.

 

[Shockwave]

I think it was made by a company called Gray and the base line had models that started with GB. Should have a round toroidal power transformer in it if I'm correct. I would check the resistors around the 4 position power switch to see if it was over driven at one time. They sometimes open up. Then I would look at the MRF492 power transistors. If they burn up usually the low value resistor between the base emitter junction burns out and is easy to spot. This all assumes the power supply is working right.

 

[TonyV225]

Ok thanks shock I never thought about Gray making these. Ive seen the Gray mobiles but wasnt aware there were bases. I sat here several times thinking about what manufacture started with a G and all I could think of was Galaxy and Ive owned solidstate bases by Galaxy and knew this was not a Galaxy product.

 

[Shockwave]

I just noticed you said the SWR was sky high. I assumed you meant the input SWR. Is the amplifier making power and you are talking about output SWR? If the output SWR goes sky high with the meter recalibrated for the amp being on, then it's probably oscillating. That would probably require negative feedback. Give me a little more info on if it's making power and what side has the high SWR?

 

[TonyV225]

Yes its making power and the SWR was noticed on the output side.

 

[TonyV225]

This is aan old thread but was talking about this amplifier today and its all good and works great I dont use it really but still have not seen another like it. Im pretty sure its a Gray Base.