I also wanted to add a note on the 680uF capacitors. The BOM specifies a Panasonic cap that is 45mm in height, but the description says 50mm. These caps were unavailable at the time so I went with 50mm caps and they are a bit too tall. I'm going to replace them, but I wanted to make sure everyone still buying parts knows that the max height on the caps is really 45mm.

The ones that andy used were 50mm, and they just barely fit.

You have to cut down the 3 front top screws to exactly .250

Better idea is to use the 45mm caps.

With the 50mm caps they touch the lip on the faceplate. You're right, I was concerned about the screws going into the cap. I could cut them down, but if you accidentally put a longer screw in it seems like bad thinks could happen.

Kerry, I am jealous

I am scared to build a KGSSHV. The T2 is a dream

our friendly monk has decided to build a second unit. One T2 is not enough

Does anyone have the part number for the testpoint connectors? I did a search and couldn't find them.

Thx

I don't think there were ever any connectors specified for those. I used some teflon units I found on ebay but I had to modify them quite a bit.

I used these for memory:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=11012-RK-ND

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=11012-BK-ND

Thinking of these to replace the nylon on the transistors:

PEEK screws

These are more money:

More PEEK

I know KG said they were $7/each (saw these at Amazon) but at the 1st link they are only $.83 each, but you have to buy 100. Are they made differently?

I am guessing the M3, 15mm will work?

Edited May 27, 201115 yr by blubliss

link fail

Another try for the first link:

PEEK

You have to navigate to the right area, this is the store.

I got some questions about the tubes.

Regarding the input tubes, do they really have to be a matched quad, or just matched pairs would be fine? I have some pairs of Siemens and Telefunken CCa but most of them are matched pair, hard to get a closest quad.

Also, is there any significant difference between the xf1 and xf2, construction or SQ? I've just scored a quad of xf1, OO. Not sure how they stand up against the xf2 which are really tough to find NOS ones these days.

No need to have a matched quad. More important to have the

halves of the input tubes matched section to section.

Thank you.

Regarding the umbilical cables, what's the maximum length I could go for? I'm thinking of 4ft length.

No need to have a matched quad. More important to have the

halves of the input tubes matched section to section.

Build my own tubetester (out of a cheap PC-scope). Lot of fun - and it seems to work

So for testing input tubes, i deducted the following from the amp-schematic - please comment:

operating points, where i need to measure:

U2:

Vgrid = -2 V

I = 5mA

Vplate = ?? cant see

U1:

Vgrid = -1 V

I = 5mA

Vplate = 69V

What is the most important parameter? Gain/mu or transductance?

Kevin,

What size reamer did you use to enlarge the C3381 holes? Looking at MSC, I'm seeing the smallest as 7/0 which is 0.0497" to 0.0666". I'd like to pick up a similar tool and am having problems finding something.

All the boards including yours were reamed with a #74 drill bit.

The 3381's fit, but are very tight. I would not go any bigger unless

you want to solder both the top and the bottom.

U2 plate voltage about 210 volts.

My umbilicals were about 3 feet. You should be able to go to 4 feet

the only issue is with the filament voltage on the output tubes

due to increased resistance.

Edited June 3, 201115 yr by kevin gilmore

Thanks Kevin, I was actually looking for the tool for another use. I didn't realize a drill bit would accomplish the same thing, until I thought more about it... I just had the word "reamer" stuck in my head I guess.

Did you stick the bit in some sort of hand tool then? I figured many chucks wouldn't down go down that low..

4 jaw thumb vise. precision swiss made thing designed for

watches. The finger thing is on a ball bearing. Not sure

where you would buy such a thing these days.

I've used it on #80 drills before. Very easy to drill

right thru your fingers without even noticing it.

ah. Thanks! I think I'll try out this one:

http://cgi.ebay.com/Double-End-Pin-Vise-Hand-Drill-w-20pc-Twist-Drill-Set-/180674981496?pt=LH_DefaultDomain_0&hash=item2a11116e78#ht_2458wt_907

Edited June 3, 201115 yr by luvdunhill

Try looking up "pin vise" for countless options.

EDIT: You changed the link right as I was posting. derp.

Edited June 3, 201115 yr by Fitz

Here's another option:

http://www.drillbitcity.com/catalogue/product_detail.asp?Tg=100-10W79-70

These are drill bits with 1/8" shafts. They've got lots of other sizes. Get extra... they break if just think about doing something wrong. I use them in my mill on PCBs.

EDIT: Ditto on the changed url

Edited June 3, 201115 yr by Kerry

Here's another option:

http://www.drillbitcity.com/catalogue/product_detail.asp?Tg=100-10W79-70

These are drill bits with 1/8" shafts. They've got lots of other sizes. Get extra... they break if just think about doing something wrong. I use them in my mill on PCBs.

EDIT: Ditto on the changed url

aaaahh.. thanks! I like the idea of not having to use a drill press though, so we'll see if I have steady enough hands.

Thanks guys!

I got a lot of practice using pin vises back when I played Battletech (and assembled the little Mech figurines), but it really isn't that hard to use one. Once you get the hole started it just becomes a matter of time; just try not to snap the bits too often.

Here's another option:

http://www.drillbitc...Tg=100-10W79-70

These are drill bits with 1/8" shafts. They've got lots of other sizes. Get extra... they break if just think about doing something wrong. I use them in my mill on PCBs.

EDIT: Ditto on the changed url

Yep. Use these in my drill press. Agreed about breakage...