TheRadioBoard

[jima]

I recently finished my latest radio. It's a one-tube regenerative using an 1t4. I built it into a cigar box I picked up on Ebay. This is the first time I've put pics and words together on the board, so I hope everything works out ok.


Here is the box I used. I picked it for its dimensions: Not too big, not too small. Also, it looks cool as heck.


The picture inside the lid was a selling point. I've seen a couple of other radios built into this box.


A closer look at the radio. The only thing left to do is put some labels on. I can't rely on my memory to not mix up the battery connections. The panel is plywood I got from Michael's. I had trouble with it splintering, but in the end it gave an antique look. I stained the panel with stain from Lowe's, and coated it with polyurethane. I haven't decided if the knobs are too modern looking for the set.


This shows how I connected the vernier dial to the tuning capacitor and how I suspended the tube and socket below the panel. It also shows more exposed magnet wire than I'm comfortable with. I worry about chafing and short circuits. If I don't take it out of the box too often I should be okay.


I got the plans from a Modern Radio Labs book. There was no coil data given, so I had to guess on the tickler and antenna coil size. Also, the values for the resistors and capacitors didn't match anything I had on hand, so I got as close as I could with what I had. I misread one of the capacitor values in the book and ended up doubling the value. It didn't seem to make any difference.

The radio is a very good performer. It's never too loud on the locals and it doesn't have any hand-capacitance induce howl when I'm on the edge of oscillation. It is VERY sensitive. I live in Tacoma and I can reliably pick up two stations in Los Angeles, about 950 miles away. Last night I nailed KFMB in San Diego. At 1,028 miles that's my first station over 1,000 miles on a radio I made myself, except for one that uses a MK484 IC chip. I'm going to be using this radio in the contest this month.

Jim

[golfguru]

Good work Jim. Looks realy great. Glad it performs they way you want it to.

[KR1S]

That's a beauty! Radio Shack may still sell spaghetti insulation (more properly called thin macaroni!). You could use it to protect the exposed lengths of magnet wire.

73,
_________________
Jim, KR1S


Just build it!
http://kr1s.kearman.com/
http://qrp.kearman.com/

[Curt Reed]

I wish I had a picture of my first cigar box radio that I built back in 1959. It had a prould type 26 globe tube standing on the top of the Roi Tan box. Yes, it worked like a charm, until my #6 dry cell went dead from running that 1.05 amp filament!

I went thru way more #6 dry cells than I should have been allowed to. At least it helped to maintain a fresh stock of them on the hardware store shelves!

I look back on it as a learning experience that never left me. and I shudder when I realize that it was just exactly half a century ago, in mid July that I built that set. I guess that sorts of dates me as an old timer at building tube type sets now!
Curt
_________________
Curt, N7AH
CW forever
Connoisseur of the cold 807

[Dan McGillis]

Nice set Jim - and nice photography.

What kind of antenna did you use?

73, Dan

[exray]

Here's mine.





I went with two 1T4s and there's space in the bottom for batteries. 4x9volt and a C-cell.

[XtalHWJ]

Jim

Rather than labels on your beautiful creation... could you figure out some way to burn the markings into the wood?

Rich
_________________
Homebrew Radio ex-Silicon Valley

[UKBB]

That is impressive jima.

[Rob Lenski]

Jima,

I'd be very proud of having built a set that nice. Great job!

"Rob"

[jima]

Thanks for the kind words. Makes my day!

The idea of burning in the labeling is a good idea. I think it would look nice, but I don't have any neat way of doing that. I have an old wood burning set like we all had as kids (remember the blisters?), but if I tried to letter with it I'm sure I would do a crappy job.

I thought about the spaghetti wrapping after I had soldered everything so It was too late by then. Also, the wire is #30 guage so I don't know how easy it is to push it through the tubing. I've never used the stuff before, but I like the professional look it gives to other radios I've seen. I'm going to get some and give it a try.

Exray, it was your 2-tube that inspired me to build mine. I'm impressed that you fit two tubes in the box. Putting the tuning cap inside the coil frees up valuable real estate. Still, that's a lot of wiring you managed to get into a small space and you even found room for a transformer!

My antenna is a 1960's style TV antenna. I keep saying I have no possible way to put up a long wire at my house, but I keep standing out on the porch looking at the trees and telephone poles and wondering what if......

The book i got the plans from was MRL Data Print File #1. It has a page with fifteen 1-tube plans.

Jim

[foolsgolden]

both cigar boxes are lovely
_________________
A proud 28 yr. old member who shares and gets ideas...

[exray]

[Austin Hellier]

Guys,
if my first valve radio looks and sounds and works as well as some of these, I'll be a happy little Vegemite. Golfguru is sending me a 1T4 in the mail and I'm busy sorting through my junk boxes for bits and pieces - win or loose, I promise you a couple of pics of the finished product over the next week or two.

Austin Hellier
'warming up'

[foolsgolden]

[golfguru]