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Resque a Galaxy Saturn ept360011b

the radio you are working on is a dual final, 20 watts per final, on am only one final is used, on SSB both finals are used. the radio is designed for 20 watt max on AM.
Modification's can make it possible to use both finals on AM, then it would have the ability to swing to 40 watts on AM, However if your going to use an amplifier you need to do the math before the modification's.
Actually, not quite correct.

Both Finals are on at the same time, in Parallel with each other.
In SSB, the Power Regulator is hard clamped to feed 12v to the Collectors of the Driver and Finals. This gives the potential to be "modulated" in SSB to 30 or so watts Peak Envelope Power (PEP).
In AM, the Power Regulator is set to output about 6v, feeding the Collectors of the Driver and Finals, thereby giving the Carrier potential of about 1/4 of full PEP, or about 8w, and allowing it to modulate it upwards to the PEP wattage of SSB. This gives the 1:4 ratio to properly modulate an AM signal.
In FM, the Carrier is the same Wattage as AM, but without the Voltage variance needed for Amplitude.
OH now I am somewhat confused guys. The specs are 10 Watt AM/FM and 21 Watt SSB for this Galaxy Saturn. And my measures are 10-12 Watt AM/FM and around 20 Watt SSB. Even when I switch my SX-200 watt meter to PEP I never see more Watts then 20. The only difference I see is that the wattage stays higher when I talk into the microphone AVG vs PEP.

I tried another radio and that does the same, so I am not worried now that the Galaxy is not ok. But technically I try to understand how to measure PEP wattage with my SX-200. Maybe that meter can't do really PEP and I will never see 30 Watts on it?
The Diamond SX 200 is not a active peak reading meter.
It uses 12 dc to light the meter but like most passive meters it likely uses some added capacitance to help hold the peaks up on SSB.
It sounds like your radio is fine, don't get to caught up on peak meter readings.

Very good info guys. To do this really perfect we need so many equipment and we don't have that. So I think with the knowledge and tools we have we are doing quiet well in having the Galaxy alive again.

It's really a drama to get parts here in Europe. I don't know if thats the same in USA I guess its all getting too old. By example where do you guys get your panel potentiometers from? We need at least 25mm in length. I noticed that my calibrate (5k) panel potentiometer is also not working, but that one has a switch function on it also. Do you have some ideas where to get those? Out here it seems almost impossible.
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32w peak × 1.414 = 45.25w PEP

My small MFJ 872 peak meter on my dummy load will read about 28w to 32w peak watts. But on my MFJ 868 True Peak Reading meter (PEP) will show around 40w to 46w PEP on the same dummy load setup. Neither meter has ever been opened at all, bought them new from MFJ.

The 872 doesn't require DC voltage to operate (only for the meter light), whereas the 868 does require DC voltage to operate (meter will not work without DC input).

My 868 shows about the same wattage I see all these Bird 43P meters on YouTube videos show by well known shops.

If you're seeing around 32w peak on your meter, then leave it alone, cause 32w peak is actually around 45w PEP, that's about right for these dual final radios. Don't stress the circuits out trying to squeeze every watt out of it. Stress will wear out parts.
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I see I arrived to the party late.

But if possible with those potentiometers - just try to remove them from the main front panel - that bulkhead and plastic, but you don't nee to unsolder any wires, just reheat the rotating part of the shaft to free up the lube inside to also provide some action to reduce some of the "scratchy-ness" or noise you get when you rotate those pots.

Its' the composition - as you found out with the Mic gain pot, that develops a "memory" where it sits at and will develop - like any thing else in life, a flat spot there that makes the pot seem worthless. A simple gentle cleaning and when stored, you rotate the pots to a stop (usually fully counterclockwise) to remove the dimple and reseat the wipers' notch that rubs across the composition to a position that is more the metal tab connection to the substrate and then when you move that knob the wiper arm then won't develop that dimple.
  • To help, the times I worked on Galaxy radios, those that had "bad pots" usually was from shipping issues - or worse, a face plant - where the knobs bore the weight of impact or thrust action because the shipper packaged the radio in such a way that the knobs - although padded to keep the radio from shaking in the box - did not and is not designed to handle a lot of weight or made to bear the brunt of getting thrown in a bin only to be pressed down further into it as the boxes of other stuff piled up on top of it. The knobs may survive - but the composition it uses to make it variable (that analog world we live in) can't survive the stress.
That is just for starters - but these radios - as your are learning - have many components that are not obtainable anymore - you can buy and use from other sources but they don't have the characteristics the OE once had.

So to tune this up, seems the you may have been in too much of a hurry to try to get it working again. The amazing thing about this here and goes to remind the rest of us, you stuck with it - because it means something to you. You got it working. But now - you have it back to specs and you just want some guidance - so if it were my equipment - being conservative with power levels and voltage supplies - work better to keep more of this board stable as you work the kinks out of that chassis that developed these issues during storage.

Wish you the best of luck on this...

And to the rest of the Clan...

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