found these, might have to do a trip down to the local hardware store: Stainless Steel Round Base Plate w/ cover Suit 2" Tube | eBay
2 inches = 50mm, size of kt88 base = 48mm
and take the chassis down with me to see how they look.
2 inches = 50mm, size of kt88 base = 48mm
and take the chassis down with me to see how they look.
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Is there a good reason why a 5U4-G couldn't be put in place of the GB?
http://www.fourwater.com/files/fullrect.txt
The G has a max plate mA of 225mA vs the GB's 275mA, is the schematic that tightly wound that it cannot accomodate an older coke bottle style G model?
The vdrop is different aswell, 44v on the G vs 50v on the GB, will putting a G model in substantially increase the B+ to the point that it would cause issues?
Would increasing the B+ by 6-12v make that much of a difference?
I've been thinking about ways to fuse the B+ line in the event that an older coke bottle style has an internal short, also I've read that monitoring the power transformer's temperature is a wise idea when doing things such as this.
Thank you for your advice.
http://www.fourwater.com/files/fullrect.txt
The G has a max plate mA of 225mA vs the GB's 275mA, is the schematic that tightly wound that it cannot accomodate an older coke bottle style G model?
The vdrop is different aswell, 44v on the G vs 50v on the GB, will putting a G model in substantially increase the B+ to the point that it would cause issues?
Would increasing the B+ by 6-12v make that much of a difference?
I've been thinking about ways to fuse the B+ line in the event that an older coke bottle style has an internal short, also I've read that monitoring the power transformer's temperature is a wise idea when doing things such as this.
Thank you for your advice.
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The total current draw for this amp is approximately 150mA.
Both rectifiers will meet this specification.
The total plate supply resistance for a 5U4G is a little higher than the 5U4GB.
The power transformer secondary resistance of 50 ohms correlates with the 5U4GB at 400V.
You will need an additional 20 ohms of series resistance if you use the 5U4G.
See the data sheets for this information.
Other than that, it will work just fine.
Both rectifiers will meet this specification.
The total plate supply resistance for a 5U4G is a little higher than the 5U4GB.
The power transformer secondary resistance of 50 ohms correlates with the 5U4GB at 400V.
You will need an additional 20 ohms of series resistance if you use the 5U4G.
See the data sheets for this information.
Other than that, it will work just fine.
thanks for that, wouldn't the resistance of the choke add series resistance though?
scratch that, I see the schematic now and its capacitor input, so it applies.
i'm looking at the datasheets now of both G & GB.
I'll do a few simulation runs tonight in PSUD and see how much 20 ohms will need to dissipate.
scratch that, I see the schematic now and its capacitor input, so it applies.
i'm looking at the datasheets now of both G & GB.
I'll do a few simulation runs tonight in PSUD and see how much 20 ohms will need to dissipate.
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This (or something matching it) will work fine:
PR03000202009JAC00 Vishay/BC Components | Mouser
or this:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtTURnxoZnJAHlhF1kLzuAqfEJMcOI0Q7U=
PR03000202009JAC00 Vishay/BC Components | Mouser
or this:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtTURnxoZnJAHlhF1kLzuAqfEJMcOI0Q7U=
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Great! Yes the transformers are definitely "beefy". Just wait until you get the OTs.
When I spec'd these to the manufacturer, I made sure they were premium.
In my opinion, the manufacturer was a little "lax" in the lamination finish, so you may want to refinish them. I've refinished the ones I've used. It's not that big of a deal to do.
Anyway, keep me posted.
Scott
When I spec'd these to the manufacturer, I made sure they were premium.
In my opinion, the manufacturer was a little "lax" in the lamination finish, so you may want to refinish them. I've refinished the ones I've used. It's not that big of a deal to do.
Anyway, keep me posted.
Scott
Now that you mention it, yes the core finish is quite a bit thin, I've got just the thing for it too, an epoxy paint.
That means I'll have to wait 2 more weeks before I can start assembling, ugh... the cans of epoxy are expensive, as is the chrome paint that I've been eyeing off, oh well the things we do for looks
Maybe I should rethink everything, I'll sleep on it anyway.
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That will no doubt be great. I just use a razor blade to sluff of the high spots and finish with a poly.
When my cousin refinished his, he just smoothed them out and finished them with hi-temp semi-flat. His photos are towards the end of the Vendor's forum thread. By the way, I think we should be posting there actually.
When my cousin refinished his, he just smoothed them out and finished them with hi-temp semi-flat. His photos are towards the end of the Vendor's forum thread. By the way, I think we should be posting there actually.
Now that you mention it, yes the core finish is quite a bit thin, I've got just the thing for it too, an epoxy paint.
That means I'll have to wait 2 more weeks before I can start assembling, ugh... the cans of epoxy are expensive, as is the chrome paint that I've been eyeing off, oh well the things we do for looks
I just use a razor blade to smooth off the rough spots, then I put on a couple of coats of satin-finish varnish.
My cousin painted his with semi-flat hi-temp black paint.
My cousin painted his with semi-flat hi-temp black paint.
Yes, they are insulated by the oxide coating.
I'm not talking about using a belt sander here. I am not shorting the laminations, just scraping off the high spots of existing rough varnish.
Good to know I would've just hit them with some sandpaper and sprayed them.
Now I know better than to cause a dead short.
I got some sanding blocks to knock off the "run" that looks to be at one corner of the transformer lams. I do understand the need to avoid shorting the laminations. I got some flat black hi-temp spray paint for these, and the motor run caps.
Question - should I make sure that the clamps for the motor run caps make electrical contact with the cap for grounding purposes? I could either tape off a section of the cap below the level of the chassis, or sand off some of the paint before mounting.
Question - should I make sure that the clamps for the motor run caps make electrical contact with the cap for grounding purposes? I could either tape off a section of the cap below the level of the chassis, or sand off some of the paint before mounting.
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