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Author Topic: DXing with a Xtal set  (Read 1404 times)

Offline pinto vortando

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DXing with a Xtal set
« on: March 02, 2019, 0323 UTC »
AM BCB conditions have been rather unsettled here in Michigan the past couple of evenings but
anyway got out my xtal set last evening around 2100 EST.
As expected, results were not too good... lots of QSB.  However, did manage to
positively ID several stations as they faded in and out:

WHAM-AM 1180  Rochester  NY
faded in just enough to get the ID, "Wham news radio 11-80"
then gone

KDKA-AM  1020  Pittsburg  PA
talking about the Pittsburg Home and Garden Show

WLW-AM  700  Cincinnati  OH
could hear it in and out under local powerhouse WJR 760
(remember this is a xtal set, selectivity isn't the greatest)

WBZ-AM  1030  Boston  MA
"Nightside" program with host Dan Rea
this station, unlike the others, had a solid signal in here all evening
Das Radiobunker somewhere in Michigan

Offline Davep

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Re: DXing with a Xtal set
« Reply #1 on: March 04, 2019, 1100 UTC »
What's your circuit?

Ill try over a few nights.  This one I used a 386 chip op amp , the slight hum in the video is from wall wart ps which can be eliminated with a 9 volt battery but it rips through them.  You can get decent selectivity by adding a trap or tuning the antenna coil and it also allows a longer antenna without overloading.
. The sensitivity is limited by the diode , not all are the same.

https://m.youtube.com/watch?v=1K4KB55-QBw


Over a few nights clipped on to the hf wire

WPTY 1690  Lexinton Pk MD  Lionel Ritchie
WBCN 1660  Charlotte NC   sports discussion
?        1590
?        1570
WFME  1560  NY NY
WGH    1310   local
WTJZ    1270 Newport News Va
WWVA  1170 Wheeling WVa
KYW     1060 Philadelphia    newsradio
WVXX   1050  Local  " La Selectra" " los top 20"
WBZ     1030  Boston
WINS    1010 NY NY
UNID    960    Political talk
WCBS   880    NY  NY
WTAR    850 local swamping adjacent
WNIS    790 local  swamping  adjecent
CFZM    740  Toronto   Rick Springfield Jessie's girl   good copy
WOR     710   New York   " WOR news time 905"
WGN    720     Chicago
WFAN   660    New York NY.  Sports  excellent copy
WSNR   620   Lyndhurst NJ
WCAO   600    Baltimore   gospel
RR        570 Santa Clara   time blips

CW on 160 meters even though the trap doesn't reach that high



« Last Edit: March 09, 2019, 2135 UTC by Davep »
Va Beach Virginia
Modified Dx 394 audio Altec Lansing ACS43
Folded dipole

Offline Josh

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Re: DXing with a Xtal set
« Reply #2 on: March 04, 2019, 2120 UTC »
1n5711 and bat46 are tops for silicon diodes, try a 1n34a for "geranium" diodes, better than a 1n60.
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Offline Davep

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Re: DXing with a Xtal set
« Reply #3 on: March 04, 2019, 2313 UTC »
I bought a 10 pack of 1n34 and checked through. Some are noticeably louder than others.
Va Beach Virginia
Modified Dx 394 audio Altec Lansing ACS43
Folded dipole

Offline pinto vortando

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Re: DXing with a Xtal set
« Reply #4 on: March 05, 2019, 1903 UTC »
What's your circuit?

Ill try over a few nights.  This one I used a 386 chip op amp , the slight hum in the video is from wall wart ps which can be eliminated with a 9 volt battery but it rips through them.  You can get decent selectivity by adding a trap or tuning the antenna coil and it also allows a longer antenna without overloading.
. The sensitivity is limited by the diode , not all are the same.

Circuit is just typical basic diode and with 250 uH coil and 365 uuf air variable condenser.
 
Not all diodes are created equal as you noticed.  Had some old (50+ yrs) germanium
type, probably 1N34,  here and picked the hottest of the bunch to use in the set.
Supposedly the old stock stuff is hotter than  new ones... idk ???
The  key is an antenna tuning unit inductively coupled to the tuning coil in the set.
The antenna coil is tuned by a couple of 365 uuf condensers in a switchable
series-parallel arrangement.  The trick is getting the proper spacing when coupling
the tuner to the set.  The closer the better for sensitivity but too close and selectivity
becomes bad to the point where stations are heard randomly all over the dial (no linear
"tracking" so to speak).

Have found that spider web wound coils seem to perform better than the usual
cylinder wound coils. 

btw, you may want to try running the op amp on 12 volts (say a couple of 6 volt
lantern batteries in series or a sealed 12 volt VRLA battery, the VRLA could be recharged if
you have the proper means to do so),  should run a looong time.  :) 
Das Radiobunker somewhere in Michigan

Offline Josh

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Re: DXing with a Xtal set
« Reply #5 on: March 05, 2019, 1950 UTC »
A tunable loop should do well in enhancing selectivity.
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Offline pinto vortando

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Re: DXing with a Xtal set
« Reply #6 on: March 05, 2019, 2007 UTC »
A tunable loop should do well in enhancing selectivity.

Never tried that with a xtal set.
Has it worked for you and if so,
how did you couple it to the set?
Das Radiobunker somewhere in Michigan

Offline Davep

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Re: DXing with a Xtal set
« Reply #7 on: March 05, 2019, 2205 UTC »
You can couple off a secondary "pick up " loop

8 ft loop radio with cool hand capacitance shields  https://m.youtube.com/watch?v=jxm2LQAO5ic.   


« Last Edit: March 05, 2019, 2345 UTC by Davep »
Va Beach Virginia
Modified Dx 394 audio Altec Lansing ACS43
Folded dipole

Offline Josh

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Re: DXing with a Xtal set
« Reply #8 on: March 06, 2019, 1858 UTC »
A tunable loop should do well in enhancing selectivity.

Never tried that with a xtal set.
Has it worked for you and if so,
how did you couple it to the set?

I think the consensus is to feed the loop with the wire, and the loop resonates/sets selectivity for the antenna system overall, keep in mind a high q loop can cut the bw down to a few hundred hz.
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Offline pinto vortando

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Re: DXing with a Xtal set
« Reply #9 on: March 06, 2019, 2047 UTC »
You can couple off a secondary "pick up " loop

8 ft loop radio with cool hand capacitance shields  https://m.youtube.com/watch?v=jxm2LQAO5ic.

Cool  8) 
wonder if the XYL would let me put it in the living room.
Das Radiobunker somewhere in Michigan

Offline pinto vortando

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Re: DXing with a Xtal set
« Reply #10 on: March 06, 2019, 2104 UTC »
Tried tuning around a bit just before sunrise.

Caught a sports station ID as 15-30,  probably WCKY Cincinnati.

The locals were mostly drowning out the DX as the sun came up but heard a faint signal...
thought the YL announcer said  WIP "Sports Radio Philadelphia"  but could not find a AM listing
for that call.  Did find a WIP FM 94.1,  anybody know the AM call and freq ?

Das Radiobunker somewhere in Michigan

Offline Boriken

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Re: DXing with a Xtal set
« Reply #11 on: March 06, 2019, 2344 UTC »
WTEL 610kc. Used to be WIP when I lived in Delaware about 10 years ago.
Scott / WB4YZA
Western North Carolina
Mosty homebrew, 100% analog

Offline pinto vortando

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Re: DXing with a Xtal set
« Reply #12 on: March 07, 2019, 0047 UTC »
WTEL 610kc. Used to be WIP when I lived in Delaware about 10 years ago.

OK, tnx.
Das Radiobunker somewhere in Michigan

Offline Davep

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Re: DXing with a Xtal set
« Reply #13 on: March 07, 2019, 1525 UTC »
I did a drive by like in the loop video, it was not late enough for dx about 2300z .  You can see why AVC was invented !
https://m.youtube.com/watch?v=miAH2tIH3nI
Va Beach Virginia
Modified Dx 394 audio Altec Lansing ACS43
Folded dipole

Offline Josh

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Re: DXing with a Xtal set
« Reply #14 on: March 07, 2019, 2010 UTC »
Oh what fun they had in the teens and twenties!
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