Great kits Ian. Passed one onto my mate who has already assembled it and got it running for one of his many battery radios. So he is very chuffed.
About to start putting my other 2 kits together & like others have posted brilliant bit of gear.

Thank you again.

Lindsay

Finally got around to putting it together last night.

Not sure if you want to know what went wrong, but anyway...

1. The jumper to select 2 volts was missing. The part that solders onto the board was there, but not the bit that plugs onto it. I used one from a dead hard drive.

2. The 4-pin green connector wouldn't fit into the holes. I had to drill them out a bit.

3. The schematic shows the primaries of the transformers as open circuit. Also the schematic was missing the front panel entirely.

Now, to actually putting it together, it was easy to follow. When I powered up, there were no B+ volts because I hadn't soldered one of the transformer pins. Once that was done, it all worked.

I was a bit suspicious of the position of the LED in the manual, so I left it until the whole thing was together. I found that the leads of the LED had to be bent where they are very slightly wider. This has it just poking out of the front panel like any professional gear.

So it works perfectly well, my only problem is I don't have any radios that have the same "A" voltage. Most portables use 7 or 9 volts.

Thanks Ian for creating and producing this project..

Hi Rob

Sorry about the missing shunt. I didn't have any at home, meant to pick some up when at the office and forgot.

4 pin connector? Hmmm, that's odd, they should have all had the same pin size....

The schematic uses a library part for the previously-available transformer which had a split primary and no thermal fuse.

Thanks for the feedback.

Hi Ian,

Have looked into the choice of valves for my radio and the A+ supply is within the current limit of the power supply.

I will unblock my email address if you can provide the cost and the means to pay for the kit.

You have designed a very flexible power supply and that makes it handy for different valve radios.

Bushman

Hi Robbbert

Most portable valve radios with 7.5 volts or 9 volts A+ requirement that I have seen have a mains power supply already built in. I can't recall ever seeing a portable with series string filaments that was DC only. And I used to fix heaps of these radios when I was a kid at high school, for the radio/TV shop at Canley Heights. What make/model are yours?

It wouldn't be hard to modify the supply to get 7.5 or 9 volts for A+ because the transformer has two 6v windings that are currently connected in parallel. Just rewire the secondary of the transformer (involves cutting a couple of tracks) to put them in series and change a regulator bias resistor. If it helps I could document these changes for you. There is a formula for calculating the resistors that I put in a spreadsheet so you can choose resistor values that are actually available.

Email me....

Bushman, prices are in an attachment earlier in this thread. Email me for bank transfer details.

Yes you are correct, those radios were capable of mains operation. The 9 volt radio is the Astor GPS (described elsewhere), and it is transformerless (and the AC cord was lost), so I was hoping to use your power supply to keep myself safe while working on it.

But I've finished now, so for the moment it no longer matters.

Since you have my email address, could you (at your convenience), send the details required to produce those voltages? I might come across the same situation again in the future, who knows?

Yes, you are wise to be cautious of those death traps. I have an Airzone in a cardboard "cabinet" that's similar.

I'll make the changes to the schematic and see if I can mark up the PCB layout accordingly.

I've designed the changes to support A+ voltages of 7.5 and 9 volts, jumper selectable.

It's a fairly simple change - 3 cut tracks, one link, 5 resistor changes. I'll email Brad the PDF and ask him to put it up here in case anyone else is in the same boat.

Bear in mind that a PS modified for 7.5V or 9V. will instantly trash a set of valves if it gets accidentally plugged into a radio wired for 1.4V. So, as it says in the instructions, label it carefully.

Series Filament Modifications Circuit Diagram

Document uploaded to Post 23.