Federal Limiter AM864 thread

[tk@halmi]

Started working on the power supply of this thing. I just noticed that Fender just rebadges Sovtek rectifiers and sell them for a buck more.

Today I ordered the 10k/600 and 15k/600 push-pull output transformers with the larger, 0.875"x1", cores. They should be here in two weeks.

 

[cannikin]

[quote author="tk@halmi"]
Today I ordered the 10k/600 and 15k/600 push-pull output transformers with the larger, 0.875"x1", cores. They should be here in two weeks.[/quote]

Tamas did you order the Transformers from Edcor too?

 

[tk@halmi]

[quote author="cannikin"]Tamas did you order the Transformers from Edcor too?[/quote]
Yes, these are the Edcor custom winds. They will have a part number by the time they ship them. I will let you know when they arrive.

 

[Svart]

awesome! I think edcor is a jewel in the rough for us!

 

[tubemonkey35]

Just tell me what you're looking for from the manual.

 

[Joechris]

Well, just to keep this thread alive, here is some progress...

Soon to become the federal magic box
:grin:

 

[NewYorkDave]

Lookin' real good!

Is that an LMB or Bud chassis? Here's the page for the LMB:

http://www.lmbheeger.com/products.asp?catid=45
Cover: http://www.lmbheeger.com/products.asp?catid=46

 

[Joechris]

The chassis is...yes, belive it or not, self made :grin:
I have acsess to some nice tools at school

 

[tk@halmi]

Wow, that looks fantastic! :thumb:
Is that a Sowter transformer in the corner?

 

[synthi]

wow! :thumb:

 

[MikoKensington]

Very Nice! I am quite eager to see the finished product.

 

[cannikin]

Sweet!

 

[tk@halmi]

This evening I got the Edcor output transformers. I put a WSM and an XSM transformer next to it to show off its girth. :green: http://mysite.verizon.net/res75okq/sitebuildercontent/sitebuilderfiles/edcor_xpp1_10k_600.jpg
The part number is XPP1-600-10K in case the picture doesn't show right.
The design specs were:
- 10K ohm primary center tapped
- 30ma DC on each primary winding
- 600 ohm secondary
- 1W secondary
- 20Hz to 20KHz bandwidth

More this weekend.

Cheers,
Tamas

 

[Svart]

is that 500k attenuator LOG or linear?

 

[tk@halmi]

It should be an audio/log attenuator.

 

[Svart]

awesome, I am gathering parts for these as I type. probably my last DIY for some time until the job thing straightens up... :sad:

I am also assuming that one PSU is enough for two channels correct?

 

[tk@halmi]

I still need to order a case for this from Par-Metal. My plans to stuff it into a 2U case I already had were spoiled by the size of the power transformer.
I am probably violating some tube equipment construction purity law, but I will be using octal relay sockets and bolting them to the bottom of the case.

 

[Svart]

i'm sitting with an old time tube guru and he says that I should actually go to a sandstate powersupply and not deal with the rectifier tube and choke..

I might just work out a powersupply for this.. any suggestions?

 

[tk@halmi]

Why not? This opens up choices for other transformers like an easy to source Hammond. You could use a hexfred, like the HFA08TA60C (@Digikey) in place of the rectifier tube, for low switching noise. It is designed for center tap secodaries and has the cathodes tied together already. http://www.irf.com/product-info/datasheets/data/hfa08ta60c.pdf

You could keep the choke, add an extra resistor to drop the voltage to where it needs to be, and add a capacitor after that for buffering/filtering. Or chuck the choke and just go with RC filtering.

I was going to do that before Edcor figured out that they could make one like the original. Not having an original unit or a manual, I have no idea what the output voltage should be under what load. Consequently, I can't tell you what the resistor value should be. I am kind of in the dark, but I am not alone ever.

 

[SUPERMAGOO]

joecris nice pics!!!!! . my version its horripilant!!