valve5425

OK, my chassis is finished. (My homage to Steampunk.) Just DON'T remind me how long this has taken! A few minor tweeks, including tightening the legs up, then I can start soldering. Another 6 months maybe?? No point rushing these things, and, to be fair, I'm only after that longest build prize. @‌dmkbox No, this is not a kit! More pics at http://cubeupload.com/codes/32d8a5

Ooops, should have read the data sheet. Would have saved me some typing! I see your problem with rotating the boards. I can't see you ending up with a massive temperature difference between the tubes, but even so, won't you be adjusting the balance at it's stabilised temperature? OK, if one tube's getting much hotter than the other, then it may shorten its life, but these tubes are cheap. Bet you wish you'd built the KGDT!

Regarding your tube mounting, from Radio Designers Handbook, Langford-Smith; "Where it is necessary to depart from vertical mounting, ............................................. the plane of the grid side rods (or major axis of the control grid) of indirectly heated valves having a high transconductance and/or a long unsupported cathode, should be vertical. This reduces the possibility of filament- and cathode-to-grid short circuits and microphony in filament valves." 6s4a data sheet; http://www.tubebooks.org/tubedata/HB-3/Receiving_Tubes_Part_2/6S4-A.PDF I don't think you would class 6s4a as particularly high transconductance, so this is probably not an issue. Don't quote me, but I think the grid plane would be horizontal in your scheme, I'll let you decide that one! Maybe someone else has mounted them horizontally? As you point out, heat could be a problem, but until you try it, you won't know with that either! Is there some reason that you can't spin the boards by 90 degrees and have the tubes side by side? After all, the boards are shorter that way. The other consideration is the sideways force on the socket, but then these are short and light enough for that to not be an issue, and I don't suppose you'll be bouncing your chassis up and down! (Larger tubes sometimes have additional support.)

Cheers. I'll post more pictures in a week or two when the chassis is finished.

I think you might have the right idea. Just get it built and enjoy it. I'll be lucky to get the chassis finished this month. Then the fun starts with the boards.

7 dollars? You were robbed! (only joking) But at least you've built it, so you have my admiration for that.!! I've got all my parts now but I'm still sorting my chassis. Elm frame, brass legs and copper top. I like a bit of weight! I HAVE to build the chassis before I get the soldering iron out. I've just too many projects with unfinished chassis. @nopants, I think this could well take over the title for the longest build, so don't pester me people.

Re. the MPSW(A)56...........Thanks for your response everyone! RS UK do have 700 in stock, min purchase of 50. It's been a couple of months since I checked with them, and ironically I drove past the warehouse this afternoon,. Doh!! Mouser UK have 5000+ of the MPSA's, minimum purchase of 1, so, in view of spritzers advice, and the fact I've a fistful of parts to get from them anyway, I'll go with MPSA. A lot less pain than the SOT23's I've got. It was a PITA trying to find the pesky little things in their anti-static bag, let alone the thought of having to solder them!

I was looking to use the MMBTA56LT1G SOT-23 version, which can dissipate 225 ma max. Looking at the schematic it shouldn't exceed that. BUT..... I'd be much happier using the 1A TO-92. Trouble is, Avnet US want $40 to ship to UK, and if I buy from Avnet Europe, it's minimum of 2000! Now I guess I wouldn't be using all those! So, if anyone's got some spare, I'd be happy to take them off their hands for a fair price + shipping, Paypal fees, etc.

Thanks for that Kevin. Yep, that's fair enough, I'll stick to getting a KGST built and working for now.

Guess I'll stand back and watch this one go!! I have a confession. I do like to get carried away with power supplies, but only if there's a chance of improvement. I mean, we don't want wimpy stuff do we. If the lights don't dim when you turn it on, is it big enough?

Thanks Kerry. See your point spritzer. Just wondered if anyone had tried both psu's and found the change worthwhile.

I'm just sizing up my chassis, so, is the KGSSHV PSU a "must do" or "could do" for the KGST? I'll be using the KGST psu initially, just to get up and running, but if it's going to be worth the effort, I'll leave some space to change psu's later. I've ordered a TX with 0-280-330v secondaries, so I'm assuming that would just get me 350V from the KGSSHV psu. My mains supply is consistently around 247v, so, with 230v primaries, I've some extra headroom. If this is feasible, I'll monitor the thread regarding the latest board until they know it's not going up in smoke! Thanks!

Thanks spritzer, got it now! I've just slapped myself across the head.

I thought these would fit? http://uk.mouser.com/Search/ProductDetail.aspx?R=MKS4O131005D00KSSDvirtualkey50520000virtualkey505-MKS4O131005DKSSD My boards will take 15mm or 22.5mm caps. The only issue I can see is that it puts the cap closer to the tube so they'll get hotter. (Max operating temp is 100°C) Also, is there a problem with the 630v caps here if you're running at 350v? FYI, I'm also at the "gathering parts" and "designing the chassis" stage.

1st post here so, Hi folks! @ s_r Great job! I've just got myself a KGST board set, tubes and Stax socket and am currently getting everything else together for the build. My downfall is that I rarely finish the chassis's on my projects, so I've made the decision with this one to get the chassis sorted before I start soldering! There's will-power for you! Anyway, did Modushop do all the work on the enclosure, i.e. top and front panels, or did you get them done somewhere else? Thanks.