RM KL-203 and Repair

[RatsoW8]

I finally found replacement parts for the KL-203 and swapped out the bad relay today. Overall this is a cheap little amp that I'm not sure is worth the new selling price. Innards and highlights of the repair are below. With two watts drive(10 meters of course) it does about 60 watts out.

First of all when I told my assistant I was taking apart a KL-203 she barked and hid under the work bench.

Underside of the board. Those look like IRF520's but are labeled RM 4.

Parts side. You can see the relay at the 6 o'clock position. I'll get to that in a sec.

The 8 relay leads are so tight in the holes on the board I had to break apart the old relay to pull the leads out and then clean up the holes.

Underside of the board showing the 8 relay solder points. Easy to get to but difficult to to de-solder.

Skipping forward to relay installed. Solder side.

Top Side.

Point of interest. This is the factory blobbed up 12 volt connection to the board. Both had cold solder joints. WOW!! I reworked this before putting the unit back together.

Well...ok I had an extra blue led laying around and couldn't resist.

 

[this_is_nascar]

I've always considered the KL-60, KL-203 and KL-300 to be throwaway amps. Treat them nice, they'll perform well, throw them out when they break.

 

[RatsoW8]

I've always considered the KL-60, KL-203 and KL-300 to be throwaway amps. Treat them nice, they'll perform well, throw them out when they break.

I forgot to mention the replacement relay cost me $2.50 plus my time.

 

[Robb]

Very nice job on the RM amp and this thread.
Any amp that is AB biased is OK in my book . . .

 

[sonoma]

I put irf520's in a friend of mine's little 203 that he over drove and burnt them up. they worked fine in the amp. a lot cheaper than the rm3 that comes in them. a little less output but not enough to justify buying the original ones. his put out about 80 watts after the mosfet changes on am and about 150 on SSB

 

[577-Jersey]

Anybody find a crossover for the relay,,I cant seem to find them for a fair price?

Thanks
577
Tom

 

[KD2GOE]

good work I am still flip flopping from the KL203 and the KL503...

 

[Lil'Yeshua]

Just got mine today in a trade. Got to figure what service it's wired for.

 

[ExitThirteen]

Just got mine today in a trade. Got to figure what service it's wired for.

12 volts.


~Cheers~

 

[Lil'Yeshua]

12 volts.


~Cheers~

Duh!?
According to the RM Italy website it looks like I have version 6. Looks like L1,L2,L3,L4 and the caps at each junction are missing plus a cap and something else in the service position area.


http://www.rmitaly.com/download/manuals/KL203-manual_rel_600.pdf

 

[Lil'Yeshua]

Don't know enough about these things yet to know any better.

 

[Lil'Yeshua]

Looks like this whole section is disconnected. Anybody know what this section does?

Well,maybe L1-4 and associated caps.

L1-L4 are 2,2 uH chokes

 

[Lil'Yeshua]

The KL203 pic on CBRadioMagazine's article doesn't have any chokes either.

But I'm missing C5 or 6 as well

 

[sp5it]

It is a place for lowpass filter.

 

[camaro1]

run it!