Parts for 300B PSE

[paul(555)]

Having acquired an unfinished kit I've now determined that a few components are missing. Thankfully this amounts to just a few capacitors i.e. C7/8, C9/10 and C15. Can anyone help with the souce of the originals?

My box of bits also includes a selection of Jensens and Black Gates, however one pair of Jensens is 0.27uf rather than the original 0.22uf part, are they useable?

Finally, the original bridge rectifiers are missing from the box, but look to have have been replaced by four marked GBPC 3506W, are these direct replacements?

Any help would be appreciated.

Paul.

[John Caswell]

Hi Paul

Initially do not go and spend a fortune on "boutique" bits and pieces.
So C7/8 were 47µF/350V can type, snap in from RS/Farnell/CPC/Arrow mounted horizontally in capacitor clips as shown.
C9/10 100µF/500v Wire ended axial types sourced from above, mounted underneath/on top of tagboard
C15 10µF/250V wire ended axial type sourced as above, mounted underneath/ on top of tagboard.
The 0.27µF Jensen Paper In Oils, as opposed to the cct diag value of 0.22µF, will not make any noticeable difference to the amp so are quite safe to use.
The bridge rectifiers were not supplied in the original Kit as the 300Bs were AC heated, so I guess these are for the DC heater upgrade. That having been said the type supplied, GBPC3506W, are more that adequate for the job as they are rated at 600V PIV/35A.
If you have any more problems please feel free to pm me or phone me accordingly

Regards

John aka Dr John

[Paul Welsby]

Paul,

so you was the lucky winner of the unfinished kit on ebay then was you?

very nice, a few people on here was watching that item closerly, myself included.

Good luck with the build. Looks like you have got yourself a cracking amp there!

Paul

[Max N]

Hi Paul
Dr John has it the wrong way round (very rare to see a mistake from the Doctor!), the 100uf/500V C9/C10 were the can type with snap-in terminals - try to source ones with the right diameter to suit the cap mounting clips - were the clips included?
The 47uf/350v C7/8 were the axial wire-ended type.
There were two bridge rectifiers per monoblock in the standard kit, one for the 6au6 heaters and one for the cathode follower HT +/- supply. The 2KBP02 is available from RS at 69 pence each (395-2954). RS also list a W04G (659-832), which is rated 400V and looks like the one supplied with the original kit. Can anyone confirm that this would be OK at 150-0-150 input, +/- 195 output @ 13ma?

[MartinJones]

I tend to use the Maplin W04 version at 18pence, though looks the same.

Martin

[John Caswell]

Hi all
Oops!! sorry! Bad day at the loony bin and senile decay setting in. Soon to collect my pension
It looks as though additional upgrade components were purchased because the thing that puzzles me are the bridge rectifiers GBPC3506W as these are not HT/small heater current rectifiers but heater type rectifiers. Also Jensen PIOs were not in the original kit
The rectifier versions Max quotes are, according to the original bumf in the supplement, correct for the 6AU6 heater and the ±195V supplies. The W04G is identical as far as ratings are concerned to the W04 and is a suitable replacement for it.

John aka Dr John

[paul(555)]

Thanks for the very helpful responses, such assistance gives me significant extra confidence.

Paul - Yes it was me, I have always fancied buying a pair and seeing these on e-bay galvanised me into action. However, what I didn't know until a few days ago was that WAD were out of action, hence my relief in finding the forum still running under a new title.

Max - No the capacitor clips were not included

Two further points:
i) what's the accepted wisdom on the best valves to use?
ii) both on/off switches are damaged, shafts pushed back through the switch, does anyone know the source for these?

Many thanks,
Paul.

[petercom]

We are now very close to getting hold of the WAD stock. I estimate it will take another two weeks from today to get sorted. As soon as we have our hands on the stock we'll announce it and take requests for spares at that time.

[Paul Bannister]

This is the switch originally supplied with the kit:

Mains Rated 4A Switch -

DPST rotary switch
RS Stock no: 316-800
Part no: RMS1016


Priced as: Each
Info. Price (£) Order
Qty
5+ 75+ 250+ 500+
£0.93 £0.874 £0.836 £0.798



October 2005 catalogue book 1 - 1656
= RoHS status under investigation
A glass-loaded flame retardant body and spindle, and silver contacts
Spindle 0.25in dia. with standard flat
Can withstand a current surge of 64A for 0.01s
Solder terminals
Contact Resistance: 20 Mohm

Regards,
Paul

[MartinJones]

Paul, be careful fitting the chrome knobs to the rotary switch. I broke 2 switches recently. Found that after cutting the length (as manual), using a sharp knife to scrape the shaft diameter down slightly makes for a non-forced fit. You force it on & the back pops off!