No more power from this PA

IK8XLD · Jan 13th 2020

Hi all,

this little PA, no longer has power suddenly, on my DATV setup.

The stabilized voltage is present, therefore the RF amplifiers, one or both, are broken.

The code of the two RF amplifiers have been deleted (see figure) , so as not to recognize the model, but I was wondering if someone was able to do it.

On one of the two, the code has not been definitively deleted and KB or KR is visible

Now a new one has come from china for a few euros and I'm working with that, but I'd like to identify the broken component.

73 Rocco IK8XLD

SV1BDS · Jan 13th 2020

Hi,

Some proposals to check:

- How is the voltage across 510 SMD R ? (you measure the current via the ohms law)

- Verify that input attenuator is OK (measure without RF & DC power the 3 resistances )

- Verify that voltage is at hot end of both green chocks without appling input RF power.

- Connect dummy load, DC & RF input of a few MHz and use an 1N4148 and a 1nF capacitor as an RF probe

to verify power at 1) attenuator input, 2) attenuator output, 3) between amplifiers, 4) output

- Verify that a few volts exist at input pin of final amplifier without RF input

SV1BDS · Jan 13th 2020

Hi, the final may be this one : 2SK2596 eBay

G0MJW · Jan 13th 2020

Just a couple of modamps. Replace with something suitable. E.g GALI-59+, PHA83W

IK8XLD · Jan 14th 2020

Tnx George & Michael,

I will work on it

IK8XLD · Jan 21st 2020

I have identified the two stages on other similar amplifier with the codes not abraded.

The first one is an SBB2089z

The second one (final) is signed KB863

No more power from this PA

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