Very cool indeed!  What software did you use to recreate the schematic.  The one I am referring to is this one:

https://www.flickr.com/photos/200030206@N06/53507396677/in/dateposted-public/

Thank you

– Wil

@wil_bloodworth

 -Visio Pro 2013.  It works well but you’ll have to make a lot of your own custom graphics.

This one was painful: Receiver Chassis Wiring

@lea I am also a fan of Visio… but you certainly took it to another level.  I questioned it because it was SO nice with all of the tube graphics and even the attention to detail with jumping wires over one another that I thought you may have used some software specifically for this.  Clearly, I need to spend more time in Visio as I don’t think I could come up with something anywhere near as nice as you have done.

– Wil

@wil_bloodworth 

-Thank you for the kind words.  I’m certainly no expert, but I find that if you have an end goal in mind, you’ll eventually brute force your way to achieving it.  As an example, I needed a way to make the OEM heater symbol, and eventually found out how to enable developer mode which allows you to stack multiple shapes and combine/cut sections away from the whole.  The heater symbol ended up being two stacked, rounded on one side rectangles, with the inner rectangle being cut away.  The only issue you’ll run into, as I’m sure you’re aware, is that with a lot of odd shapes there are no centered snap points for the wires.  The only way I’ve come up with to get the wires where I want them, is to align micro circles where the wires should connect and then send those circles to the back layer.  If you were to look at the back layer it would be full of circles/squares/rectangles used for alignment; it’s time consuming but the end result is achieved.  I’m not saying Visio is the most efficient software for the job, but that’s all I have and it’s paid for. 😎

Incredible restoration and documentation, good job! I love when LEA goes “…I’m not an expert…” 🤣 🤣 

Really excellent work on all counts.  Very clear to understand.  Outstanding work.  

Dear @lea, 

What kind of soft start component has been used to drive the 2 fillament transfomers ? I am working on a simlilair radio, is this to prevent the inrush in the transformers ?

Thanks

Henk

I used a soft start module for the the entire radio power, not just for the filaments. 

The power supply has a B+ regulator and modern diodes, but also has more capacitance (22uf after chokes and 22uf after B+ regulator) as well as the original chokes.  So to help lighten the load on all components, it didn’t hurt to have a little current limiting.

The soft start module used was from CZH Labs/ Electronics Salon:

( ELECTRONICS-SALON 115Vac Mains Power ON Delay Soft-start Protection Module, with 12 Vdc Regulator. )

It has an adjustable, 0-10 second time delay adjustment before bypassing the NTC thermistors.  It comes with 4 thermistors.  NTCs 1&2 parallel connected, NTCs 3&4 Parallel connected, with sets 1/2 and 3/4 connected in series.  These were swapped out with two 120ohm NTC in series; 240ohm total.  The timer on the board is just a 555 timer, so I removed to the pot and put in a fixed value resistor to up the time to 30 seconds.  What I wanted was the radio to ramp up to near is operating voltage over that 30 second time.  Right now it’s a little slow.  I haven’t played with the soft start since, but I think the ramp delay problem is from sharing the NTC heating load between two thermistors; a single 180-240 ohm NTC would heat up quicker thus increasing the voltage ramp.