The AM Forum

Picked up this amp to restore or use with the 5100/51SB or for building a transmitter. Its not beat but neglected and real dirty. Anyone know what color these things were before spray cans got invented? Match my 5100? ....another project

Thanks!
EdZ KG6UTS

The front panels were B&W Gray with white lettering and border about 1/2' in from the edges.

Don't know what the case was. Mine was hammered with the spray can too!

Thanks! Looks like the front panel paint will clean off 'cause the gloss wasn't prepped before the spraycan mass-a-cree. All, glorified overspray....  I figure beefing up the power supply with solid state rectalfryers, new caps and a bigger xfmr might give this antique some 'authority'. Their later LPA-1 kinda did that.

EdZ KG6UTS

Ed,

As stated the L-1000A should match the 5100 while the LPA-1 is a tan to match the later rig.

Thanks again! This looks like it will be an OK Radio Revival project. I've used my 5100 and 5100B on AM but wanted to put a BA-SSB  station together to play on the the local, Southern Calif, classic SSB net. The 5100 with 51SB and L1000A should have cajones but the L1000A has potential for mod to be good on AM as well as SSB. Still makin' chicken scratch on paper....


73!
EdZ KG6UTS

Well, dove into the L1000A this morning. The power deck is pretty clean but the RF deck was nasty, mixture of oil, dirt and rodent residue. I field stripped the RF deck to get the mung off the chassis which cleaned but...the mung ate a lot of the cad plating. There are some chassis markings that looked rubber stamped:

OUTPUT       (self explanitory)
 B&W Insp    (in a circle, probably acceptance of the chassis itself??)
 #572          (not sure if it is the serial for the amp or part of the inspection process) Anybody know?

Obvious problems besides loots of cleaning:
   The bandswitch knob is stuck on the shaft and spinning. Seems like the shaft was worn and mushroomed by the loose set screw, might be a while on that one.

 The plastic/fiber coil supports for the 850 network are shot. It looks like the supports are two parts, the coil comb and the bracket piece. The combs look ok but the brackets have curled away from the combs and cracked. I have a lot of 'alligator' used to line chassis holes etc that matches the coil pitch but am not sure on the type of plastic to use for the bracket pieces. Any experience with that?

Happy Thanksgiving!
73
EdZ KG6UTS

Hi Ed,

Those coil struts or whatever they are called, always get heated and cracked over time. It would be nice to restore them but they are not essential for operation, as I'm sure you know. Basically they are bakelite with high temp epoxy. I have used ceramic strips with high temp epoxy to replace them, but the epoxy does break down over time as well.

One solution I have been pondering over is the use of various hi-temp plastics. One is Tivar (UHMW-PE High Temperature) sheets cut on a bandsaw to size and notched for the coils. Also I have been thinking of various Teflon formulations. I still have to check on the electrical or magnetic characteristics of these materials. Here's a site that has some of this stuff: http://k-mac-plastics.com/uhmw-sheet-High-Temperature.htm

I'm working on one of these amps (actually I have two) myself. I do suspect the amplifier has a plate transformer that is lacking. You may consider finding one you could use externally that is a bit beefier. The LPA-1 had a transformer that was a little better from what I understand. I am using a transformer from a BC-610 (Stancor 52B046) which really seems to work well. I think HUZ has one for sale in the FS forum. Nice iron, plenty of current reserve for this amp.

Also I would recommend checking and/or upgrading C109, the capacitor across the B+ choke. They always seem to get burned up on those amps. I would upgrade to the same capacitance but a 5kV voltage rating. The original is 3kV. It's an oil paper cap. With a 5kV you can run a higher plate voltage (like I do with the Stancor) and not have to worry about that cap. For AM use the amp works better at a higher plate voltage. I like 2kV running at about 200mA.

Good Luck with it.

John
W2WDX

Hi Ed,
.......... I do suspect the amplifier has a plate transformer that is lacking........
Good Luck with it.
John
W2WDX

Thanks for the heads up on the caps etc. I've ordered electrolytics and 816s from Antique Electronics Supply and have a 5KV in the shop for C109. The stock rebuild should be fine for SSB with my 5100 and 51SB but a tougher external pwr supply is planned, just need a chassis. The Thordarson xfmr and choke set will finally come out from under the desk.

The deck was finished and the power supply in work then my job sent back to Afghanistan...need a new travel agent. Anyway here is the RF deck

........"Also I would recommend checking and/or upgrading C109, the capacitor across the B+ choke. They always seem to get burned up on those amps. I would upgrade to the same capacitance but a 5kV voltage rating."
Good Luck with it."

John
W2WDX
[/quote]


I found some 6KV models and bought extras. Thanks for the heads up and if anyone needs one its your for postage.

EdZ KG6UTS

Look. There's a spot on the chassis for another 813!!!

The aluminum knobs should buff up real gooder, Ed!

Welcome home and thanks!

She cleaned up really nice.

Fred

Here's an idea for those coil "comb" spacers that we used on W1IA's GS35B amp: We took that flexible grommet stuff used to line the inside of chassis holes.  We cut off every other finger and slipped it into the coil and tied it in place with the waxed nylon used for wire looming. It came out nice. I'll have to get some pix up, the web page needs updating anyway.


Mark

Eggs Ackley!!! I used it too but we call it "alligator"  I used it with touches of E-Pox-E to firm stuff up. It isn't in the pictures but it is there now.

EdZ

I was at the store yesterday where I bought it; they call it "caterpillar grommet".