My Multi-Band hybrid Crystal Radio

[G0CWA]

Hi another of my crystal radio sets. This one is again on http://makearadio.com/index.php at http://makearadio.com/visitors/nick.php where full constructional details and more photos are shown. The front panel and control layout is shown below but because of the nature of the set the tuning scale is only a rough guide and exact calibration is not possible.

I appreciate that to the dedicated crystal radio enthusiast this is not a true crystal radio.



This set uses plug in coils for the different bands and given a very good antenna and earth with an ATU will hear stations up to around 14 MHz.

When I made the chassis I included a small draw to store the coils in so they could be kept with the set. The coils are wound on perspex tube with a DIN plug mount.

This mount was used to make changing of coils easier and the ease of obtaining the connectors over the more usual octal plug method.

I used an origional method of varying the selectivity / sensitivity for a Mystery Set (see the description) although the set is still basically a Mystery plus.


Not sure if this is a promise or threat but I will be posting more later, the next offering will be two versions of stand alone horn speakers, one LM386 based the other using a carbon ampliier in about a weeks time.


Enjoy your building 73 de Nick G0CWA

[KO6WB]

Hi again Nick, I'm still mulling over the previous post but I can see that the improvements on this example may be something to consider. I never really tried using a crystal detector above the AM broardcast band. That is with the exception of some tunable field strenght meters. This is more fuel for the fire. I need to find the wire for making the coils. I'm wondering how well a crystal set will work on the SW bands. I have often seen the WWII examples of their SW radios that used a razor blade as a detector. Apparently they were able to receive BBC rather well. I'm surprised they weren't jamming them.
Okay Nick another good post. Not sure Sue had time to make your previous example. I know I didn't.
BTW I used to make tube amplifiers for my crystal radios. Those were the days.
Thanks
73
Gary

[W4HAY]

Gary, go to the XTAL Set Society website and click on the parts link for Litz wire and other goodies.

The Society also has an active forum.

[G0CWA]

SW radios that used a razor blade as a detector

Hi Gary

Apparently the old gillette blue was concidered to be the best blade to use, something to do with the method of heat treatment and the "Blue" coating. With I believe best sensitivity to be found on or near the writing. I have used one with success. but they are not as sensitive as a lump of galena and far more difficult to set up and find the "sweet spot"

TTFN Nick G0CWA

[N1NQC]

Hey All,

Nick GREAT work!.

Gary, SW xtal sets cans work VERY good IF good building and RF practices are applied.I'd avoid razors and use (preferably) a diode or rock until the set is known to work well.Razors are VERY touchy to get and keep operational and seem to require big signals.The Schmarder Radio Board is the more active site lately.

K

[KD8DEY]

The hottest detector I ever had was a diode out of an old TV tuner. funny looking thing.
made similar to a small glass fuse and snapped into a holder, BUT the metal ends were conical.

I have never been able to find a reference to any similarly constructed device.
Forget what brand of TV it was in (been over 30 years)

[N0SYA]

The hottest detector I ever had was a diode out of an old TV tuner. funny looking thing.
made similar to a small glass fuse and snapped into a holder, BUT the metal ends were conical.

I have never been able to find a reference to any similarly constructed device.
Forget what brand of TV it was in (been over 30 years)

What do you think of these?
http://www.angelfire.com/electronic2/index1/bat46.html

[KD8DEY]

What do you think of these?
http://www.angelfire.com/electronic2/index1/bat46.html

I have never used one that I know of. Except for packs of 1n34A's from Radio Shack, all the diodes
that I have used have been unknown pulls from junked equipment.

(I do have a small batch of original Phillips Bat-85 I haven't tried that were mailed to me from a friend in the Netherlands)

[K6ABZ]

That's impressive, Nick. The amount of work you've put in to this is obvious, and I love your attention to detail. This thing looks a far sight better than most commercial equipment you can buy; I keep telling people that I want to refit an old 30's or 40's broadcast receiver, and this is why: to get that beautiful wood look.

Keep up the good work!

[G0CWA]

That's impressive, Nick. The amount of work you've put in to this is obvious, and I love your attention to detail. This thing looks a far sight better than most commercial equipment you can buy; I keep telling people that I want to refit an old 30's or 40's broadcast receiver, and this is why: to get that beautiful wood look.

Keep up the good work!

Hi thanks for the compliments about the set. I know what you feel about the wood look, it just has a warmer feel and is far more tactile than metal (or plastic). It just cries out for you to play with the set. I try to not just think of the electronics but the artistic content/layout. On most of my sets the lables and scales are printed on photo paper at photo quality stuck to the panels with PVA and then multiple coatings of varnish. Have a look at http://makearadio.com/visitors/index-nick.php to see some of my other sets my favorite is the "3250" dual 1625 set.

73 for now Nick G0CWA