Re: [Drakelist] L7 PS Winter Project
Definitely do the bleeders too. I would also consider laying a slow turning fan on the top to assist in drawing out the hot air. I just place four little rubber bumpers on a 4 fan (so it doesn't scoot) and run it at about half voltage. Heat buildup is your enemy. Dennis AE6C On Thu, Oct 1, 2009 at 8:51 PM, Richard Radke rar...@excite.com wrote: Brian, I've done Mike's (The Heathkit Shop) rebuild. 1st rate, clear instructions, pretty simple. Replaces most everything but the 50K bleeders and the bias resistor. Jeff at Harbach has those available. I'd do those also. Rick W9WS On Oct 1, 2009, at 8:41 PM, bjon...@mindspring.com wrote: I picked up a L7 from ebay. The amp itself looks to be in excellent condition but the power supply is a different story. It looks like someone started to take it apart to rebuild the boards but they only got as far as removing one of the boards. Before I try to rebuild the existing boards (I think I have most of the parts to do it) should I just go ahead and get one of the replacement/upgrade single boards? Along those lines can anyone suggest either the board from The Heathkit Shop or Harbach? Since the power supply has already been partially dismantled is there anything I need to watch out for when rebuilding it (either with the existing boards or the upgrade board)? Lastly... does anyone know what kind of screws were used on the case for the PS? This one is missing all of the screws. Thanks Brian KD4UYP ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] L7 PS Winter Project
I picked up a L7 from ebay. The amp itself looks to be in excellent condition but the power supply is a different story. It looks like someone started to take it apart to rebuild the boards but they only got as far as removing one of the boards. Before I try to rebuild the existing boards (I think I have most of the parts to do it) should I just go ahead and get one of the replacement/upgrade single boards? Along those lines can anyone suggest either the board from The Heathkit Shop or Harbach? Since the power supply has already been partially dismantled is there anything I need to watch out for when rebuilding it (either with the existing boards or the upgrade board)? Lastly... does anyone know what kind of screws were used on the case for the PS? This one is missing all of the screws. Thanks Brian KD4UYP ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] L7 PS Winter Project
Hi Brian, As far as I know, Heath and Harbach boards are the same. Be careful with hardware and make sure that there is enough space between surrounding components to prevent arc over. Be sure and change the resistor in the bias circuit. Can't lay my hands on my instructions right now, but as I recall, that is covered. I also can't get to my PS-4 and 7 so I can't tell you about the screws. If the RF deck has the original power/mode switch, I suggest you install relays and switch the coils with the switches instead of the load. This is easy to do and there is plenty or room under the chassis to do it. You might also consider a soft start circuit at the same time. Both these mods are easy and completely removable with no holes. When you are setting things up, be sure that the input AC is correct for the input voltage. There is a terminal strip in the deck and one in the PS that makes this easy to do. Both must be set up for the same input AC voltage you are using. I suggest a heavy ground lead between the deck and PS. Do not rely on the internal power cable to handle this. Of course, the whole works should be properly grounded. Note that if you are running it on 240 and plan new wiring from the breaker box to handle it, you will need to run 4 wire cable, that is 2 hot, one neutral and one ground. This is a recent change in the NEC. If you presently have a 220 circuit to the shack you are grandfathered. This only applied to new work. 73, John, W4AWM ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] L7 PS Winter Project
Brian, I've done Mike's (The Heathkit Shop) rebuild. 1st rate, clear instructions, pretty simple. Replaces most everything but the 50K bleeders and the bias resistor. Jeff at Harbach has those available. I'd do those also. Rick W9WS On Oct 1, 2009, at 8:41 PM, bjon...@mindspring.com wrote: I picked up a L7 from ebay. The amp itself looks to be in excellent condition but the power supply is a different story. It looks like someone started to take it apart to rebuild the boards but they only got as far as removing one of the boards. Before I try to rebuild the existing boards (I think I have most of the parts to do it) should I just go ahead and get one of the replacement/upgrade single boards? Along those lines can anyone suggest either the board from The Heathkit Shop or Harbach? Since the power supply has already been partially dismantled is there anything I need to watch out for when rebuilding it (either with the existing boards or the upgrade board)? Lastly... does anyone know what kind of screws were used on the case for the PS? This one is missing all of the screws. Thanks Brian KD4UYP ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
