messed up my ameritron al-800h :(

[Moleculo]

well, last night I found out I messed up my Ameritron AL-800H somehow. All the sudden the input swr on 40 meters is about a zillion:1. I guess I'll have to take it in to see what's wrong. It's fine on all the other bands.

 

[AudioShockwav]

Bandswitch? tank Coil?
Check solder connections in this area....(I don`t have a lot of time so here is a quick cut and paste)

The second problem I found was the 80 meter tank coil was toasted as some others have mentioned. There was no glue in that area, but the plastic rods that support the coil turns had apparently softened from high heat, allowing the turns to collapse under their own weight and a couple of turns were shorted together. You can buy a new coil from Ameritron for around $54, already prepared to solder in place. I elected to buy the uncut coil stock from them for $35, and see if I couldn't improve on the arrangement. Whereas the original coil had been prepared by removing an entire turn where the 160 and 80 meter coils meet, I cut the coil at that point on the bottom, using a Dremel tool and pushing in the adjacent turns a bit so I could get the cutoff wheel on the desired turn. The result is a more rigid coil structure.

The next problem was that I couldn't get full output on 40 meters, and the the output power drifted downward within a second or so of applying drive. I went into the final tank compartment and heated all the connections to the 40 meter tank coil with my 140 watt gun. The construction there really isn't very solid and the tank coil ends simply pass through the circuit board and are soldered. After reflowing the solder at those points and on the bandswitch, the 40 meter problem was gone.

Will check back with you later..
73
Jeff

 

[Moleculo]

Great, now to top it off, the temperature control knob on my soldering station just broke off.

I think someone may be trying to tell me something...

 

[Peddler]

YUP

 

[NorthStar]

Cbers do that to the HF amps all the time.

 

[AudioShockwav]

LOL!
It went to the Dr yesterday, lets see if Mole gives us a Report on the result of the check-up.

73
Jeff

 

[Moleculo]

hahah....you're funny Northstar! Well I took it over to the shop, and as soon as we popped the cover off the rear panel that covers the input tuning circuits, I spotted the problem quick. The coil had just come un-soldered from the 40m pad. No big deal after all....a little solder and it was good to go. What sucks is now I can't do anything at home involving soldering (unless I can use a gun) until I get my solder station repaired under warranty