Prototypers wanted

[Nebby]

I'll have to file that fact away for future reference, at this rate pretty soon I won't have to order from digikey anymore! I ordered the Panny's from Digikey since I had a couple items I needed to get from them anyways. Thanks dsavitsk and TomB for the great support, looking forward to building this loooooooong amp!

[TomB]

Yeah - that looks like a great choice on the switch. I searched for days on Mouser - even asked them for a quote to manufacture another 100 or more of the original one we used, but to no avail. So, way to go!!

I'm a gutless coward when it comes to sarcasm through digital communication, so let me be clear: Nate helped tremendously with his idea on the Google spreadsheet and I am certainly kidding about slacking on the BOM. Between work and a baby girl (been there, done that twice), I'm surprised he gets anything done. I should've done the BOM before and kept Nate or Doug from the work in doing one. But hey - at least I got 'em packed and shipped.

[Nebby]

I think I spent a good hour or so on mouser's site before I gave up and pulled out the dead tree version. Pulled up the data sheet for the EOL'd version and went from page to page until I found one that had the same size/dimensions. Turns out that giant catalog is good for something after all

Definite kudo's to Nate as well! Hopefully everything will show up in time for a weekend build then I can have an amp to run headphones with (currently ampless, heh)

[Fitz]

The prototype 1/2 kits have been shipped. I'll send you each a Delivery Confirmation # when I get home tonight.

Great news. Probably gonna be a few days before I can afford to order the remaining parts though.

[Pars]

The Mouser BOM I got from Tom appears to have quantities to build two amps... two IECs, etc. Was this intentional or am I misreading things?

[dsavitsk]

The Mouser BOM I got from Tom appears to have quantities to build two amps... two IECs, etc. Was this intentional or am I misreading things?

You aren't building two?

[Pars]

^ Was only planning on doing one.

[TomB]

Sorry about that. Seems I always order two of everything!

[luvdunhill]

Yeah, I noticed that as well and tried to adjust the quantities. In my case, I actually was ordering two of everything, so it was confusing that it actually was correct The differences between Doug's list and Tom's list are subtile. MKP4 versus MKP10 caps, generic diodes, etc. so, it might be worthwhile to look at both lists. The only point of confusion I had was the power ratings for R4L, R4R, so I fully intend to check the schematic out when I'm building it and verify this one. Also, don't order the headphone jack and pot from Mouser if you ordered the 1/2 kit, almost made that mistake. Also, I didn't order any heat sinks.. it might be worthwhile to add that to Tom's BOM, as I didn't realize this until after I place the order... but I should have some on hand hopefully that will fit.... Anyways, parts are incoming!

[TomB]

Well, if you go by my BOM, check the quantities on every item. I can confirm that the items themselves are OK - that's what's inside my amp that's been running for months now (RN55's definitely used at R4). Even in cases where I ordered double, I sometimes get extras beyond that. For instance, there's a qty of 4 listed for the RCA jacks, but only 1 is needed. The pic on Mouser is mis-leading. If you click on the data sheet, you'll see that it's an integral assembly with both Left and Right jacks imbedded in the single assembly.

Sorry about not listing the heat sinks - I keep a bunch of those on hand already, so I didn't need to order them. I've added the 1-1/2" version to the Mouser BOM. Part # is 532-531102B25G. The 1" one is 532-531002B25G. I think the 1" one is probably not enough if you put the lid on the case, but remember that you'll have to grind off the top corner of the 1-1/2" one if you use it. Also, Doug already mentioned the little slip-on BJT heat sinks - those are only at DigiKey, I believe.

[dsavitsk]

The only point of confusion I had was the power ratings for R4L, R4R, so I fully intend to check the schematic out when I'm building it and verify this one.

R4L and R4R set the CCS current. Each should drop ~1V at ~13mA.

Also, I didn't order any heat sinks..

In a pinch, for the CCS transistors, cut some little sinks out of a disposable pie tin.

[luvdunhill]

I cannot seem to find a voltage anywhere on the schematic, so ... what's the minimum safe voltage for the big film caps?

[n_maher]

I think it's discussed earlier in the thread, memory says ~200V (B+ + a little headroom).

[luvdunhill]

Ah I should have looked here first. In fact the cap I'm looking at is rated 200VDC...

[dsavitsk]

200V is too low. The PT is rated at 200VAC. Unloaded it runs at ~275V or so which is what the parafeed caps will see before the tubes start conducting, so I wouldn't use anything lower than 300V.

[luvdunhill]

200V is too low. The PT is rated at 200VAC. Unloaded it runs at ~275V or so which is what the parafeed caps will see before the tubes start conducting, so I wouldn't use anything lower than 300V.

Thanks Doug!

[Nebby]

the Amp 1/2-kit showed up today along with some digikey parts. The chassis sure is looooooooong

[Nebby]

Okay....for the heatsink that came with the kit, where is it supposed to be go and how is it supposed to be attached?

[Pars]

Kit showed up today. Guess I'd better get busy! Thanks Doug and Tom,

[luvdunhill]

Mine too. I kitted the other half of a kit and things are looking pretty good.

I noticed I'm missing a fuse, and it doesn't seem to be on the BOM. Any recommendations?

Also, those case tops need a bit of grease, mine was impossible to move by hand even...

Do either of you guys have a FPE file I could use as a template to cut the end panels?

[dsavitsk]

I noticed I'm missing a fuse, and it doesn't seem to be on the BOM. Any recommendations?

200mA should be good.

Do either of you guys have a FPE file I could use as a template to cut the end panels?

Tom drew up a template at one point ...

[TomB]

Okay....for the heatsink that came with the kit, where is it supposed to be go and how is it supposed to be attached?

5 x 20 mm, 0.25A slo-blo. Mine is also 250V, but anything sufficiently over 120V will be OK.

Okay....for the heatsink that came with the kit, where is it supposed to be go and how is it supposed to be attached?

Centered over the PT.

Hmm ... I guess Doug and I are reading this at the same time. I'll try to post a template momentarily ...

[TomB]

Tom drew up a template at one point ...

http://www.diyforums.org/Les/construction/templates/TorpedoEndplates.pdf

http://www.diyforums.org/Les/construction/templates/TorpedoTop1.pdf

http://www.diyforums.org/Les/construction/templates/TorpedoTop2.pdf

Note that I put two vertical rows of 1/4" holes ( 8 holes, total) on the side of the case adjacent to the heaters supply heat sink (next to all those 3/16" top holes).

All of the above addresses the heat issues, except that some side holes at the tube positions could help. It depends on how much heat you're willing to accept at the coupling caps, I guess (maybe Doug can add some opinions here). Mine ran without any side holes at the tubes all day, both days at CanJam.

[n_maher]

Tom,

Any way to get a few more dimensions on those pdfs? When I open up the end panel drawing it's almost entirely dimensionless.

[TomB]

Tom,

Any way to get a few more dimensions on those pdfs? When I open up the end panel drawing it's almost entirely dimensionless.

It gets very messy, Nate. Also, you guys need to check every bit of it. I did a better job on Doug's endplates than I did on mine. I think it's drawn more carefully than the first time I did it (Doug's and mine), but you guys will still be testing things if I dimension in detail.

Coming up ...