Rocketbox info thread !!! Made in the USA with a reasonable pricetag !

[Shadetree Mechanic]

You are correct on the 1000 board. The common relay terminal connecting to the output, is in parallel from the top view. That can only mean the NO and NC connections are also paralleled on the bottom of the board. That indicates they knew there was a weak link with this relay.

Unfortunately this does not double capacity of a small relay that is being hot switched. This only works when the relay is not hot switched because the failure here is related to the arcing that occurs during hot switching which, fuses the contacts together as they pit from the arcing. Do not expect both sets of contacts to be in perfect alignment or to wear evenly.

Eventually one side will switch before the other and arc together at the same power level one would. Proof of this is that when they fail, testing or dissecting the relay always shows one set of contacts fused together and not both.

Running a low dead key will probably help it a little too.

 

[Highway Man]

with all you knowledgeable techs on this forum the builder my decline in open conversation. cheap plastic parts and a 899 price tag doesn't jive for the working man.
the green box is still cool

 

[Shockwave]

Running a low dead key will probably help it a little too.

Yes, but now imagine SSB word peaks when the relay drops out between them and reengages on the next one.

 

[blasphemy000]

Let be realistic here for a moment. As another member has stated, these are not RF Mosfets. They are some sort of rebranded/repackaged switching Mosfets that were most likely meant for power supply operation of a couple hundred kilohertz at best. I have yet to see any actual legitimate lab-style testing of these devices. You know, gain testing, IMD3 and IMD5, other types of distortion, heat output, ect. They do work, but I seriously doubt that they will produce a full 100W/each cleanly, especially at 27MHz. And 2 driving 4? That seems uneccessary. I can't comment on the amps themselves, or the builder, so my views are purely about the Mosfet devices inside. I really need to get off my ass and take the 4 that I bought and put together a test rig with them and run them through some paces. Other projects in the pipeline though unfortunately.

 

[Shadetree Mechanic]

I think the radios being manufactured now days have finals that aren't specked for RF either.

 

[blasphemy000]

I think the radios being manufactured now days have finals that aren't specked for RF either.

You'd be correct. There seems to be very few that use real RF devices these days. It's such a shame too.

 

[Shadetree Mechanic]

You'd be correct. There seems to be very few that use real RF devices these days. It's such a shame too.

I would think that with all the WiFi and cell phone technology around, there would be a big market for RF output devices. Or maybe the cell towers run mosfet finals haha I don't know.

 

[Shockwave]

I apologize for being negative but goal here is to provide insight to the forum in order to make educated purchases. Sometimes this is not to the benefit of the builder, other times it is. That depends on the builder and what their goal was. You can buy a 10 pack of ERF9530's for $39.99. That's close to what a single quality RF transistor might cost. That's about as cheap as you can get and this market has already driven the profit on the part up from probably well under a dollar each. If you don't start with a quality output device, nothing you can do with the circuit will compensate for that afterwards.

 

[undertaker]

Just going to stick with my TX Star...…………….

 

[2NC995]

Just going to stick with my TX Star...…………….

Hard to go wrong with what we know works.

 

[Pappas and Beer]

"Just going to stick with my TX Star...…………….
Hard to go wrong with what we know works."

That's the spirit, stick with what you know rather than risk something new. Let's not be too adventurous. Man are you getting old. What happened to that desire to create new things? Take a risk with that "old" radio operator ingenuity. Be not afraid.

I have used several of the old Palomar FET amps and some were made by "Vern" out of Texas and he was in his late eighties when he was making them in the early 2000's. They worked great, lot's of forward swing.

 

[543_Dallas]

I needed a small driver and bought a RM Italy KL 7505 over a Texas Star. I'd buy one of these rocketbox amps with their inferior transistors just because it isn't a Texas Star.

 

[Tallman]

I'm with ya there Tallman, these kinda look like re-branded Palomar fet amps from several years ago. When they stopped making the ERF7530 final production died. Now that these 9530 finals are being made it was only a matter of time before someone brought these mosfet amps back to market. Have to see how well they work on SSB when members start buying them.

I fixed a few of them but never used one on the air. I know the auto SSB does not function that well. I think the switch works better. When testing on AM the amp was slow to unkey cutting the receive portion for a couple of seconds.

 

[Shockwave]

They do work, but I seriously doubt that they will produce a full 100W/each cleanly, especially at 27MHz. And 2 driving 4? That seems unnecessary.

Because these are not linear RF devices, their input gate capacitance is higher. This is one of the most important specifications for RF and every other MOSFET datasheet publishes it except Palomar. Because it's high, the gain gets very low at 27 MHz. and they require a lot of drive to overcome this gate capacitance which, causes more heat. Real circuit gain is about 9db, where 5 watts drive only produces about 40 watts output per stage. So, one stage is usually not enough and two stages are usually overkill that needs to be cut back.

 

[Pappas and Beer]

These need to be bought and tested. They probably work as good as any and maybe as good as the TS.