Yes those amps are engineered by the descendants of past amp builders so the design may look familiar to some old timers.
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Rocketbox info thread !!! Made in the USA with a reasonable pricetag !
- Thread starter WINKDOGG
- Start date
The board in this 500 looks better than the 1000 pictured in the other thread. Here we can see the area on the board towards the right of the output transformers, is all filled in with grounded copper. However, the same 1 amp relays we might see in a small 100 watt amplifier are being used in all models, right up to the 1000. Hot switching the little relay contacts with an RF sensing circuit will have limited life at these power levels.
Especially when you consider the 1 amp, 60 cycle AC rating is far more than the 30 MHz. RF rating could ever be.
Good point I didn't not notice the same relays are used in the 1000 I thought they were light for the 500
. Im certainly learning as this thread grows ! I just want to get one of these to put it through its paces gotta wait till payday I am certainly no expert and I like hearing others peoples points and learning ! I have been playing with cbs amps and antennas since I was 15 and I never stop learning new shit. I think that's why I still like the hobby so much 73's
I'm 67 years old and I learn new ways to do things. I think if you quit learning you have died.Good point I didn't not notice the same relays are used in the 1000 I thought they were light for the 500
73's
Shadetree Mechanic
Delaware Base Station 808
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.
Shadetree Mechanic
Delaware Base Station 808
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.
Looking at the "Palomar" datasheet for the EFR9530 is a bit of a joke. It looks nothing like the information provided for a real linear RF MOSFET. It is the complete void of much part specific information including rise time, fall time, input and output capacitance, turn on and off delay time, reverse transfer capacitance, on resistance, as well as a host of other things including charts showing the perimeters for the safe operating area. The disclaimer informing you that the cheap plastic part can explode, causing fire and injury was different too.
The reason for this is that Palomar has nothing to do with the manufacturing of these transistors and disclosing the complete specifications would also reveal the original inexpensive part number, before re-branding. You could then type the specs into Mouser's transistor search page and find more than one similar part. These are cheap switch mode MOSFET's being "stressed" into linear operation. I've experimented with many parts in this plastic package and abandoned them all in order to trade low cost for reliability and performance. There are a few exceptions to this but none in the 12 volt high power class or with performance that compares with strip-line terminals and BeO insulation. I also haven't seen a solid state RF amplifier struggle to make 10db per stage in over 25 years.
The reason for this is that Palomar has nothing to do with the manufacturing of these transistors and disclosing the complete specifications would also reveal the original inexpensive part number, before re-branding. You could then type the specs into Mouser's transistor search page and find more than one similar part. These are cheap switch mode MOSFET's being "stressed" into linear operation. I've experimented with many parts in this plastic package and abandoned them all in order to trade low cost for reliability and performance. There are a few exceptions to this but none in the 12 volt high power class or with performance that compares with strip-line terminals and BeO insulation. I also haven't seen a solid state RF amplifier struggle to make 10db per stage in over 25 years.
