[ARC5] Crystal Headphones

[Jim Hill]

A little more on using sound powered phones (with crystal sets).

Back in the heyday of high-performance crystal sets (I think around 
the early 2000's), sound powered phones were considered the best, 
with the RCA "big cans" the ultimate.  A matching  transformer was 
required, and Fair Radio sold one that worked well. I bought some, 
and they worked fine, Fair Radio ran out of them, so started 
substituting others without mentioning that fact.  I don't know how 
they worked, but listening tests with a UTC multi-match transformer 
indicated that the ratio was not critical.

I'm and off-and-on crystal set dxer, but have a severe problem.  I 
live very close to 50kw KNX 1070, so my crystal set DXing is done on 
camping or RVing trips.  I remember that my best location was at a 
campground near Grand Canyon.

A big aerospace crunch in that era caused crystal set on-line 
activity to drop dramatically, I guess everyone was out "looking", or 
at least spending more time doing other things.  For example, I had 
an extra Boonton Q-meter, a very desirable item for crystal set 
builders when attempting to design the best coil.  I am getting old 
and am downsizing my radio gear, so decided to sell it.  It was 
really difficult.  Nobody knew what a Q-meter was, and I finally 
found someone at an ARRL convention swap meet who wanted to tinker with it.

If you are interested in high-performance crystal sets, two good links follow:
Stay Tuned http://www.crystalradio.net/.
Birmingham Crystal Radio Group, www.crystalradio.us/
The Birmingham group was dormant for years, but seems to be active now.
Let me know if you know of others.

Regarding Brush crystal phones.
Over the years, I managed to find a few.  They worked well, but sound 
powered phones worked better.  I tried out two recently; both still 
work. They look like a capacitor, so a parallel resistor is needed 
for crystal sets.  Bill: let's talk about crystal phones.

Jim

At 08:41 AM 9/17/2018, you wrote:
>Content-Language: en-US
>Content-Type: multipart/alternative;
> 
>boundary="_000_DM5PR03MB2908D79DED1359EF29D8E0F5CB1E0DM5PR03MB2908namp_"
>
>   Many years ago, 50's and 60's some company made high impedance 
> crystal headphones, not ear phone but Headphones.
>
>They were quite sensitive. I am doing a study of headphone and 
>earphone sensitivity and have an assortment of crystal earphones,
>
>ceramic earphones ( including the ones used lately with crystal 
>radio kits that are terrible) and magnetic headphones (2kOhm) and
>
>a few odd ones.
>
>   I have GR calibration source and fixtures and such and am ready to start.
>
>Today, one can't make a sensitive crystal set due to poor earphones 
>that are available. I plan to try a design of my own after I finish
>
>the experiment modeled after the old style crystal earphone but 
>using a ceramic cantilever bimorph and foil diaphragm.
>
>If you have a set of crystal headphones and want to have them 
>compared with the others, please contact me.
>
>
>73
>
>Bill wa4lav
>______________________________________________________________
>ARC5 mailing list
>Home: http://mailman.qth.net/mailman/listinfo/arc5
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:ARC5 at mailman.qth.net
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html