6m Larcan Conversion

[nz5n]

Low measured resistance from input/output connectors to ground, why?

I replaced the input and output connectors on my Larcan (K4DLX kits) and was surprised that I read a short on my ohm meter from the center pin of both connectors to ground. I assumed I had messed up and inadvertently soldered the hot sides to ground. But now my friend tells me he is getting the same readings. It is not shown on the schematic, but there does seem to be a trace that goes from each connector to some kind of feedthrough, not sure what that is, but I assume that somehow accounts for the low resistance.

Could someone enlighten me?

73, Bill NZ5N

 

[avistar23]

i will be performing that mod on my 847, seems very straight forward, also just because you see a short at DC does not mean it is a short at 50mhz, which im sure you were already aware of, studying the board may show why you see that.

 

[vo1ks]

Perfectly normal.

Trace the wiring on the amplifier module. It will go to a coil towards the middle of the board, and then continue towards the front. From there you will see a through board connection to ground.

http://members.rennlist.com/warren/larcan3.JPG

I have other pics on my web page.
http://members.rennlist.com/warren/6meteramp.html

I replaced the input and output connectors on my Larcan (K4DLX kits) and was surprised that I read a short on my ohm meter from the center pin of both connectors to ground. I assumed I had messed up and inadvertently soldered the hot sides to ground. But now my friend tells me he is getting the same readings. It is not shown on the schematic, but there does seem to be a trace that goes from each connector to some kind of feedthrough, not sure what that is, but I assume that somehow accounts for the low resistance.

Could someone enlighten me?

73, Bill NZ5N

 

[nz5n]

Perfectly normal.

Trace the wiring on the amplifier module. It will go to a coil towards the middle of the board, and then continue towards the front. From there you will see a through board connection to ground.

http://members.rennlist.com/warren/larcan3.JPG

I have other pics on my web page.
6M / 2M kilowatt amplifiers

Thank you, Warren. I did see that long trace and was wondering where the feedthrough went, my readings make perfect sense if it goes to ground. That is not shown on the schematic for some reason.

73, Bill

 

[avistar23]

6 is wide open, logged about 30 contacts in the last 30 mintues, from Canada, to new york, to Ohio.

 

[vo1ks]

Has anyone managed to get their Larcan amps operational yet?
Any pictures to share?

 

[Captain Kilowatt]

Sort of onthe back burner for now with me. Too busy rebuilding the HF tower and antennas s well as getting ready to tear a shed down andrebuild another as well asclear the basement out in pre for a heat pump instzllation. Lots ofwork but nothing to due with 6m except the antenna installation.

 

[vo1ks]

Excuses...

 

[Captain Kilowatt]

Excuses...

And poorly written ones too ifyou look at that post. Man I hate this keyboard on this phone. Ctually the keyboard is great butit misses now and then. Big fingers, little buttons.

 

[avistar23]

Ive been busy, i was in Miami buying some international trucks, im back now, finishing tiling my apartment, the amplifier cabinet is mostly completed, and i received my directive systems yagi today, about a 3 month wait, nothing compared to the 4 months ive waited for gulph alpha at this point. also got my dual line section with the antenna.

 

[vo1ks]

I picked up a Larcan TV transmitter that uses a 6-transistor PA module for high band television. It's not the 6-meter version, but the modules can be fully swapped out. None of the filtering and metering circuits will be reused. From here all that is needed is a transmit/receive relay and a low pass filter.

The rack may have enough room to install a second amplifier module, either for 2kW total output, or a even dual band amplifier for 6M and 2M.

 

[Captain Kilowatt]

Nice. Very nice. Complete with power supply as well. Sorry I was not able to help you unload it Warren but that may have been a good thing in the end as it may have ended up in the bed of my new truck and headed for my house before you knew what happened.

 

[vo1ks]

Unloading wasn't as bad as expected. Pulled it out a bit, lowered to the ground, and then stood it up. The corner dollies really help with moving things around. The exciter was left behind. I didn't need the suspicion of putting the transmitter on air.

The only failure the transmitter had in its less than 10 year use was when the output power became intermittant. The PA was removed and the rear panel monitoring board connector pushed back in place. The cooling air flows from the fans and out the side of the module. With 24/7 operation, it allows dust to collect on top of the circuit board.

Too many projects happening and no idea when this one will ever be put to use.

 

[WA8ZYT]

Wow! Nice! That would make a nice 2 meter KW amp! Our local university TV station has one of those running only 175 watts on Ch5 digital, (10-1) for weather and radar.

Still collecting parts for mine. Anyone got any photos of metal work to shield the circuit board?

 

[avistar23]

Very nice, would love a cabinet like that.