I built a radio just for fun. - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

Backtoreality · 4th Jun 2020, 4:40 pm

What a great idea! I've just found 3 twin backboxes in the garage and I nearly threw them out last week because I had the house fully rewired a couple of years ago! Well done!
David

llama · 10th Jun 2020, 1:08 pm

I've just knocked this set up using part I've had around for years. Wanted to compare it with the set I built a few months ago:

https://www.vintage-radio.net/forum/...d.php?t=165249

using my RV12P2000 but I can't find another socket so I just used croc clips. The coil looked like a salvaged MW one so I used that. All the little strips of prototype PCB are double-sided onto the IKEA baseboard and the pot is double-sided taped to it too.

I find it rather more interdependent regarding tuning/reaction and the aerial loading is heavier but then I haven't used a separate winding or tapping for it. However, the reaction is nice and progressive.

I tried wiring the pot as a variable resistor with its bottom end decoupled to ground but that was no good as it didn't reduce the gain enough so I've reverted to the circuit as given. Mine being an indirect heated valve, I redrew the circuit to make it easier to follow. So thanks again for the intitial pointer.
Graham

PsychMan · 10th Jun 2020, 2:02 pm

Awesome! backboxes as a mini valve chassis!

Woohoo, I knew there was a reason I had kept some

G6Tanuki · 10th Jun 2020, 5:06 pm

I just did a bit of research and it seems that the small 3- or 6-pin circular Bulgin chassis-sockets fit nicely into the smaller knockout-holes, which could be a useful and convenient way of feeding HT/LT into a 'backbox project'.

G6Tanuki · 10th Jun 2020, 8:24 pm

It's also worthy of note that there are 3-way back-boxes available, and also MK list a "869ZIC 47MM BOX" which looks like it could easily house something like a small 5+5W stereo amplifier [a 12AX7 dual-triode feeding a couple of 6AQ5] or - with the VFO built on a separate back-box for stability - a "Codar AT5" 1.8/3.5MHz AM transmitter-clone.

[My next project is likely to be a 3.5MHz regen receiver using a 1S5 valve and a couple of transistors, built into a back-box!]

davidw · 11th Jun 2020, 8:37 am

I'm very surprised and pleased my little idea has proved interesting to you all. I just need to buy shares in a back box manufacturer now!

vu2nan-nandu · 15th Jun 2020, 10:39 am

Great show, OM Dave!

73,

Nandu.

4th Jun 2020, 4:40 pm	#21
Backtoreality Hexode Join Date: Oct 2007 Location: Ossett, West Yorkshire, UK. Posts: 406	Re: I built a radio just for fun. What a great idea! I've just found 3 twin backboxes in the garage and I nearly threw them out last week because I had the house fully rewired a couple of years ago! Well done! David

10th Jun 2020, 1:08 pm	#22
llama Octode Join Date: Jun 2006 Location: St Osyth, Nr Clacton, Essex, UK. Posts: 1,482	Re: I built a radio just for fun. I've just knocked this set up using part I've had around for years. Wanted to compare it with the set I built a few months ago: https://www.vintage-radio.net/forum/...d.php?t=165249 using my RV12P2000 but I can't find another socket so I just used croc clips. The coil looked like a salvaged MW one so I used that. All the little strips of prototype PCB are double-sided onto the IKEA baseboard and the pot is double-sided taped to it too. I find it rather more interdependent regarding tuning/reaction and the aerial loading is heavier but then I haven't used a separate winding or tapping for it. However, the reaction is nice and progressive. I tried wiring the pot as a variable resistor with its bottom end decoupled to ground but that was no good as it didn't reduce the gain enough so I've reverted to the circuit as given. Mine being an indirect heated valve, I redrew the circuit to make it easier to follow. So thanks again for the intitial pointer. Graham Attached Thumbnails __________________ Half my stuff is junk - trouble is, I don't know which half!

10th Jun 2020, 2:02 pm	#23
PsychMan Octode Join Date: Jun 2013 Location: Fleet, Hampshire, UK Posts: 1,764	Re: I built a radio just for fun. Awesome! backboxes as a mini valve chassis! Woohoo, I knew there was a reason I had kept some

10th Jun 2020, 5:06 pm	#24
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: I built a radio just for fun. I just did a bit of research and it seems that the small 3- or 6-pin circular Bulgin chassis-sockets fit nicely into the smaller knockout-holes, which could be a useful and convenient way of feeding HT/LT into a 'backbox project'. Attached Thumbnails

10th Jun 2020, 8:24 pm	#25
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,995	Re: I built a radio just for fun. It's also worthy of note that there are 3-way back-boxes available, and also MK list a "869ZIC 47MM BOX" which looks like it could easily house something like a small 5+5W stereo amplifier [a 12AX7 dual-triode feeding a couple of 6AQ5] or - with the VFO built on a separate back-box for stability - a "Codar AT5" 1.8/3.5MHz AM transmitter-clone. [My next project is likely to be a 3.5MHz regen receiver using a 1S5 valve and a couple of transistors, built into a back-box!] Attached Thumbnails

11th Jun 2020, 8:37 am	#26
davidw Heptode Join Date: Sep 2006 Location: Woodbridge, Suffolk, UK. Posts: 643	Re: I built a radio just for fun. I'm very surprised and pleased my little idea has proved interesting to you all. I just need to buy shares in a back box manufacturer now! __________________ Dave G1AGK. My perception is my reality!

15th Jun 2020, 10:39 am	#27
vu2nan-nandu Pentode Join Date: Jul 2014 Location: Bangalore, India Posts: 132	Re: I built a radio just for fun. Great show, OM Dave! 73, Nandu. __________________ https://nandustips.blogspot.com