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Author Topic: 40m Novice Operation  (Read 2126 times)
AB8IF
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Posts: 19




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« on: January 29, 2011, 06:51:46 PM »

I am finishing up construction of a crystal-controlled converter that will allow me to listen to shortwave bands on my home-made regen receiver. If this setup operates well enough on the 40m ham band, I plan to follow up with a complementary home-brew transmitter...

Thirty years ago I enjoyed working CW with novice operators on 40m. These were the hams that were the life-blood of amateur radio's future!

My question... Is regular novice operation still around on 40m? I've heard sporadic novice-like signals around 7110kHz, but I wonder about the general health of this mode of operation Huh

73,
Roger AB8IF
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K6LO
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Posts: 226




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« Reply #1 on: January 29, 2011, 10:08:22 PM »

Well it is certainly nothing like it used to be, but there is still regular activity there often at slower speeds than found toward the bottom of the band.

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KB3TXH
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Posts: 44




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« Reply #2 on: January 30, 2011, 06:57:30 AM »

I hear near constant, slow CW activity, between 7.105 and 7.119 .
The folks I work are general, or extra class, and all seem happy to send between 5 and 10 wpm.

Jim
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NO2A
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Posts: 742




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« Reply #3 on: January 30, 2011, 03:13:26 PM »

 Hi Roger,since the new extra phone band starts at 7125 khz,you could get crystals anywhere from 7100-7120 would be fine,though most stations i`ve heard are right around 7110-7115. I never got to use an old xtal controlled transmitter. Makes me wish i had an old Drake 2NT,or similiar rig. Good luck with the project.-Mike.
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W7ETA
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Posts: 2528




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« Reply #4 on: January 30, 2011, 03:30:28 PM »

7.025 is a common mil surplus xtal.

So far, I've only built the xmitter and power supply from the 1949 HandBook, 6L6 driving a 6L6.  I used a Pi network and wound a coil around a pill bottle.

It was great FUN and a real pain to go from the schematic into 3 dimensions.

What amazed me most is that it worked!

73
Bob
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AB8IF
Member

Posts: 19




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« Reply #5 on: January 30, 2011, 05:37:32 PM »

7.025 is a common mil surplus xtal.

So far, I've only built the xmitter and power supply from the 1949 HandBook, 6L6 driving a 6L6.  I used a Pi network and wound a coil around a pill bottle.

It was great FUN and a real pain to go from the schematic into 3 dimensions.

What amazed me most is that it worked!

73
Bob

Bob,
Is there a link to that 6L6/6L6 schematic?
73
Roger


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NK6Q
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Posts: 202




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« Reply #6 on: January 30, 2011, 06:17:19 PM »

Yeah, I want to see the schematic too!  I've been toying around with the idea of making AI2Q's 6L6 transmitter, but have yet to scrounge up the parts to get going.

Bill, NK6Q
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W7ETA
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Posts: 2528




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« Reply #7 on: January 31, 2011, 11:39:19 AM »

I've been told that the 6L6 driving the 6L6 is very hard on the xtal.

Her is a similar design using a 6AG7:
http://www.qsl.net/k5dh/6ag7_6l6.html
That design is in the 1948 HardBook
The 1949 has the 6l6-6l6.

Those old ARRL HandBooks are cheap on eBay and get mailed at a cheap book rate.

If you poke around the ARRL site you might find an article from QST?

If you give me your email adr, I'll send pixs of the power supply and xmitter.  DO Not buy octal socket made in Cihina!  Even if they are touted for Fender guitars.  Be forewarned, there are at least 3 different diameter octal sockets.

You can also scan "GlowBugs" and get a few designs.

Best from Tucson
Bob
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K5TEN
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Posts: 143


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« Reply #8 on: January 31, 2011, 03:24:21 PM »

I am in total envy of the OP.   Grin


I remember working hard as a young (just) married man in the early 80's.  I was lucky enough to pick up a used set of Kenwood Twins.  I worked harder and bought a Vibroplex bug.

I remember MANY cold and drafty winter evenings in Waukegan, IL--sporting my new KA9 call...listening on 40m in the evenings and all those HUGE 20 and 30 over S9 Novice band signals pounding in from 4 and 5-lands...and all the great QSO's at 100w and a vertical with plenty of radials in the yard.

The radio GLOWED (at least the transmitter did) and the contacts were great memories.

I miss that.
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AB8IF
Member

Posts: 19




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« Reply #9 on: February 10, 2011, 11:07:02 AM »


Her is a similar design using a 6AG7:
http://www.qsl.net/k5dh/6ag7_6l6.html


Thank you for the link Bob! My next construction project may look a lot like this one.

Roger AB8IF
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W0FM
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Posts: 2052




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« Reply #10 on: February 10, 2011, 11:16:59 AM »

Roger,

Bravo for taking the home-brew path.  I was a Novice in 1962 but still enjoy the feel of radio with old rigs.  If you have trouble finding parts, or not necessarily hooked on building some rigs from the "ground up", check out the old replicas offered at

http://www.pastimeprojects.com/transmitterkits.html

I've enjoyed several great weekends building some of Glenn's old-style kits.  They work....any they "glow" too!  Have fun.

73,

Terry, WØFM
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N2EY
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Posts: 3833




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« Reply #11 on: February 10, 2011, 04:07:06 PM »

I've been told that the 6L6 driving the 6L6 is very hard on the xtal.

A lot of old designs were. Back then typical ham xtals were bigger and could take more current. When FT-243s appeared after WW2, they were considered tiny!

Her is a similar design using a 6AG7:
http://www.qsl.net/k5dh/6ag7_6l6.html

Thanks for the link, it's a pretty good design. The modified-Pierce circuit used in it is much easier on the crystal.

However, the rig could be improved in a few ways (IMHO):

1) Parasitic suppressor may be needed in the 6L6 plate lead. In some stubborn cases the grid lead may need one too.

2) There should be a 2.5 or 1 mH RFC across the output for safety.

3) The B+ switch should not be in the B+ lead. It should break the connection of the HV center-tap winding to ground.

4) A larger coil (physically, not inductance) in the pi-net is a good idea.

5) There should be a way to measure the 6L6 grid current during initial tune-up so that the drive can be set correctly.

6) A 5U4 can be substituted for the 5R4 in the power supply. Both will work but the 5U4 is more common.

73 de Jim, N2EY
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