QRZ! Ham Radio 3/QRZ Ham Radio Callsign Database - Volume 3.iso/digests/homebrew/930118.txt

Internet Message Format | 1994-06-04 | 14KB

Date: Tue, 30 Nov 93 04:30:29 PST
From: Ham-Homebrew Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Homebrew Digest V93 #118
To: Ham-Homebrew


Ham-Homebrew Digest         Tue, 30 Nov 93       Volume 93 : Issue  118

Today's Topics:
                      1 TUBE transmitter for QRP
                      24 volt device on 12 volt
                             Information
                          QRP phone- ideas?
                      sw-radio coils...question.
                     Upgrade to a Micor (2 msgs)
                 W7EL's Optimized rig: saga continues

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policies or positions of any party.  Your mileage may vary.  So there.
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Date: 29 Nov 1993 16:48:56 GMT
From: library.ucla.edu!europa.eng.gtefsd.com!avdms8.msfc.nasa.gov!news.larc.nasa.gov!grissom.larc.nasa.gov![e-mail]
Subject: 1 TUBE transmitter for QRP
To: [e-mail]

In article <[e-mail]> [e-mail] (Randy) writes:
>
>Note...a 6CL6  or 12BY7  ( different socket wiring) will work the same
>as this one will....so, a sub of tube ( and rewire socket ) can be done.
>Those 2 tubes are 9 pin mini tubes
>12HG7 will sub 12BY7 directly.     ( if ya need info on that, buzz me)

I'd bet that if you tweaked voltages a bit, you'd be able to use a 6L6
in that circuit as well, and get a significant amount more power out of
it.  The 6L6 on 80M is good for about 25W in a single-tube design, or
maybe 15W on 40M.  You can even do 10M with the thing, but the interelectrode
capacitance kills you; you get about 2W with the plate glowing cherry red.
--scott
   (whose first transmitter used four 6L6s and a 12AX7)
--
"C'est un Nagra.  C'est suisse, et tres, tres precis."

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Date: Sun, 28 Nov 1993 18:22:43 GMT
From: swrinde!cs.utexas.edu!howland.reston.ans.net!agate!iat.holonet.net!pubcon![e-mail]
Subject: 24 volt device on 12 volt
To: [e-mail]

my guess is that by lowering the voltage, you are also lowering the
power output to the antenna. therefore, say if youre puttint out 100
watts, if all the power is reflected back in phase, you will have 200
watts total at the transistor. now, having said that, seeing that
p=ExI, assuming the voltage is half of the original, if you use a
device capable of handling 200 watts, it should be ok, but at the
higher voltage, power is increased and therefor exceedes the power
limitation of the device. that is my guess. as far as the differences
between fets and bipolar devices, as i recall a bipolar is a current
driven current output device. i dont think voltage will matter much in
its operation unless it has a minimum operating voltage in the specs.
the fet is a voltage controlled current supply divice so voltage could
oops should not effect it either. thats my thinking, but im not an
expert on transistors by a longshot. i had a hard time with that
course. :) 73 wb5kxw

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Date: Mon, 29 Nov 1993 20:08:19 UTC
From: qualcomm.com!vixen.cso.uiuc.edu!howland.reston.ans.net!pipex!uknet!EU.net!sunic!trane.uninett.no!news.eunet.no!nuug!news.eunet.fi![e-mail]
Subject: Information
To: [e-mail]

     INFORMATIONAL REPORTS

- How to trick pay phones into thinking you deposited money

- How to clone cellular phones

- How to make traffic lights turn green by remote control

- How to build and use a bugging device

- How to make your electric meter go backwards

- How to get cable TV for free

- How to create your own pirate TV or radio station

$10 each, or all for $40.  For informational purposes only.  Send self-
addressed, stamped envelope.  Make checks or money orders out to Kardos.

Kardos
P.O. Box 2310
Darien, CT  06820
USA



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Date: 29 Nov 1993 15:45:41 GMT
From: munnari.oz.au!bruce.cs.monash.edu.au!harbinger.cc.monash.edu.au!msuinfo!uwm.edu!vixen.cso.uiuc.edu!ux1.cso.uiuc.edu![e-mail]
Subject: QRP phone- ideas?
To: [e-mail]

Does anybody have decent experience with a rig to do phone on QRP, something
lightweight, low power?  If there's anyone who's messed with this, please
respond with some ideas on where I could build such a rig via e-mail.  Thanks.
Andy N9NTI
--
We're just two  lost souls  swimming in a |  If the University saw things my
fish bowl, year after year.  Running over |  way, they wouldn't raise tuition!
The same old ground,  what have we found? | Andy Peterson, N9NTI     /--/--/
The same old fears.. wish you were here.. | "I only do code in C."      |

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Date: 29 Nov 93 14:32:42 GMT
From: psinntp![e-mail]
Subject: sw-radio coils...question.
To: [e-mail]

In rec.radio.amateur.homebrew, [e-mail] (  antonio gatta) writes:
>Hello there.
> I'm not sure if this is the right place to ask but the title seemed
> appropriate (and I couldn't find a faq).  Anyhows, I'm working on
> a crystal shortwave radio which requires a t-50-2 toroid core onto
> which the coil is wound.  I'm wondering if a straight (bar) ferrite

They are similar in that both are used to increase the inductance of a
coil.  However, type 2 iron powder of 10, while ferrite materials usually
have a much higher permeability (though some VHF materials have a similar
permeability).  Ferrites typically have higher loss, though I've seen
inductors wound on type 67 material with low loss.  Many will have 1 to
2 magnitudes more loss.  Ferrites are often less frequency stable.

You might consider replacing the coil with an air core inductor, which
will also have low loss and probably even better frequency stability.
A problem is the large field generated by air core inductors unless
shielded--you can probably fine tune the circuit by waving your hand
around it!

People have wound these on a cardboard form, though styrofoam would
probably have a little less loss.  Books such as the ARRL Handbook
tell you equations for finding out the inductance of both toroidal
and solenoidal inductors.

Zack Lau  KH6CP/1

Internet: [e-mail]           "Working" on 24 GHz SSB/CW gear
             Operating Interests: 10 GHz CW/SSB/FM
US Mail: c/o ARRL Lab           80/40/20 CW
 225 Main Street    Station capability: QRP, 1.8 MHz to 10 GHz
 Newington CT  06111                modes: CW/SSB/FM/packet
            amtor/baudot
Phone (if you really have to): 203-666-1541

> core wouldn't achieve the same end.  (Plus, I can't find the toroid
> around here--I'm rather close to finishing it so ordering it would
> most likely kill me :)
>  If the bar does work, could anyone give me a tip on how
> many turns (of wire) it would need.

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Date: Mon, 29 Nov 1993 16:33:32 GMT
From: library.ucla.edu!europa.eng.gtefsd.com!howland.reston.ans.net!news.moneng.mei.com!uwm.edu!ginews![e-mail]
Subject: Upgrade to a Micor
To: [e-mail]

In article <[e-mail]> [e-mail] (Bill Shymanski) writes:
> .....  At our last executive meeting, I was
>told we've had a complaint that our "flagship" repeater has
>a front end so broad that it lets in calls 20 khz off-channel -
>this is well past the adjacent channel and getting into the
>deep woods.   The VHF receiver is a Micor mobile, with the
>usual adaptions to repeater service.   Is it possible to
>get some third-party upgrade filter to tighten the response
>a bit, and upgrade this - or should we start saving
>up for a commercially built repeater ?

Hi Bill,

Most MICOR units have very good front ends on them.  However, there
were some units that were built with a DVP unit that have a 24KHz
passband in the IF.  If you converted one of those units and did not
modify the IF passband, then that could be your problem.

   Donald D. Woelz, K9GR              Office Phone: [phone]
   GENROCO, Inc.                      K9GR @WB9TYT.#MKE.WI.USA.NOAM
   205 Kettle Moraine Drive North     [e-mail] [44.92.1.48]
   Slinger, WI 53086   U.S.A.         [e-mail]

------------------------------

Date: Sun, 28 Nov 1993 15:24:09 GMT
From: ucsnews!sol.ctr.columbia.edu!emory!kd4nc!ke4zv![e-mail]
Subject: Upgrade to a Micor
To: [e-mail]

In article <[e-mail]> [e-mail] (Bill Shymanski) writes:
>Never volunteer to be on the technical comittee of a repeater
>club unless you have some idea of what's involved:
> Anyway....I'm a member of a repeater group that is currently
>involved in interconnecting repeater sites in several spots
>in southern Manitoba.   At our last executive meeting, I was
>told we've had a complaint that our "flagship" repeater has
>a front end so broad that it lets in calls 20 khz off-channel -
>this is well past the adjacent channel and getting into the
>deep woods.   The VHF receiver is a Micor mobile, with the
>usual adaptions to repeater service.   Is it possible to
>get some third-party upgrade filter to tighten the response
>a bit, and upgrade this - or should we start saving
>up for a commercially built repeater ?
>( And is this problem related to the fact that the repeater is
>on a CBC broadcast tower with 100,000 watts of various
>broadcast transmitters on it ? )

Bill, Micor receivers aren't as good as it gets, but they are
close. So if the Micor is picking up 20 kHz off channel signals,
and it's working properly, then just about any other receiver
placed at the site will suffer the same fate. However, the Micor
*shouldn't* be having this problem. The IF filtering is quite
good. What this likely means is that your Micor is sick.

Here's what I would do. First I'd look at the LO output with the
spectrum analyzer to see if it's got noise spurs. This could be
bringing out of bandpass signals onto the IF frequency. If the
result of this test is negative, I'd run a response curve for
the receiver. Sweep across the channel input and observe the
limiter current with a scope synced to the tracking generator.
(Most spectrum analyzers will allow for this type of connection.)
The response should be at least 60 db down at the +/- 20 kHz
points. If this test is passed as well, then the basic receiver
is not at fault. Obviously if it fails one of these tests, do
the appropriate repairs.

Another possibility is that some of that high power crud is
getting into the front end of the receiver and generating
spurious mixing products that mix with off channel signals
and bring them into the bandpass. I'm assuming you're doing
like most people and using only notch duplexers for the
repeater. I'd try adding a pass cavity to the receiver side
and see if that helps.

Finally, it may not be a repeater problem at all. It could be
that some local user types are running their rigs "all knobs
to the right" and generating very broad signals. You didn't
say whether the received signals were clear or not. If all
you're getting is buckshot, I'd start DFing some users with
bad radios after I'd determined the Micor receiver was operating
properly. (You don't see this problem too often with modern Japanese
equipment, but some of the older rigs were quite bad.)

Gary
--
Gary Coffman KE4ZV          | Where my job's going,  | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | I don't know. It might | uunet!rsiatl!ke4zv!gary
534 Shannon Way             | wind up in Mexico.     | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244     |          -NAFTA Blues  |

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Date: 29 Nov 1993 17:26:09 GMT
From: library.ucla.edu!agate!howland.reston.ans.net!math.ohio-state.edu!news.acns.nwu.edu!casbah.acns.nwu.edu![e-mail]
Subject: W7EL's Optimized rig: saga continues
To: [e-mail]

This is as a follow up on my earlier tale of woe in which I mentioned
the low VFO output.  I thank all, including W7EL, who replied.

I replaced the FET and the VFO output came right up to 5vpp with the
buffer output at 2.4vpp.

I replaced the receive section of W7EL's Optimized rig with Rick Campbell's
R1.  For a test, I hooked up an antenna and the oscillator (thru the
buffer) to the SBL-1 mixer in the R1.  The receiver seems quite
insensitive.  Only signals S7 or better were audible on the receiver. It
is quite deaf.

On to more fun ...

Rajiv
aa9ch
[e-mail]

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End of Ham-Homebrew Digest V93 #118
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