QRZ! Ham Radio 3/QRZ Ham Radio Callsign Database - Volume 3.iso/digests/homebrew/930112.txt

Internet Message Format | 1994-06-04 | 11KB

Date: Wed, 24 Nov 93 04:30:44 PST
From: Ham-Homebrew Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Homebrew Digest V93 #112
To: Ham-Homebrew


Ham-Homebrew Digest         Wed, 24 Nov 93       Volume 93 : Issue  112

Today's Topics:
                    [Q] transistor info for OC83B
                     Anybody marketing HF kits ?
                    Direct Conversion with CW RIT
                      single sideband generation

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policies or positions of any party.  Your mileage may vary.  So there.
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Date: Mon, 22 Nov 1993 10:32:32 GMT
From: munnari.oz.au!spool.mu.edu!howland.reston.ans.net!pipex!Q.icl.co.uk!dsbc!iclbra!ss11![e-mail]
Subject: [Q] transistor info for OC83B
To: [e-mail]

Hello world, Sorry if this is the wrong place for this posting.

I am looking for a spec sheet for a 1960's germanium transistor made by Mullards of type OC83B. It forms part of the circuit for a tachometer in a Smiths instrument.

Many thanks in advance...      regards  Kai Tsang

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Date: 23 Nov 93 20:03:36 GMT
From: ogicse!emory!gatech!howland.reston.ans.net!agate!etch-eshop.Berkeley.EDU![e-mail]
Subject: Anybody marketing HF kits ?
To: [e-mail]

 I'm wondering, does anyone know if (who) markets Ham radio kits.

I'm not yet involved in the hobby, But I could get interested in
building an HF rig. I seen mentioned "Daves kits" here om the net.


    Thanks

    Ron Viegelahn

    [e-mail]



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Date: Tue, 23 Nov 1993 18:56:11 GMT
From: sdd.hp.com!cs.utexas.edu!math.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!news.csuohio.edu!vmcms.csuohio.edu![e-mail]
Subject: Direct Conversion with CW RIT
To: [e-mail]

I had a HW8 with added RIT, and loved to be able to go above or below
the zero-beat point.  Also, zero beating was a snap -- turn off the
RIT, zero beat to zero frequency, and flip the RIT back on and adjust
it to a comfortable audio freq.  This does not seem to be possible with
dual conversion SSB/CW equipment.  Is it?
------ Phil Emerson, AA8JO

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Date: Fri, 19 Nov 1993 13:48:24 GMT
From: EU.net!ieunet!tcdcs!news.tcd.ie!unix2.tcd.ie![e-mail]
Subject: single sideband generation
To: [e-mail]

Newbie Question Time :
 Why bother to eliminate the offending sideband in the
 transmitter at all ?

If the RX is good, It shouldn't be confused when you tell it to listen
to an ssb signal and then tune it to a DSB one, should it ?
Or is the idea of transmitting DSBSC not a good one (ie. wastes EM
bandwidth) ?
Hiding behind my newbie status to avoid great big red flaming followups,
EI5EDB.

--
Mark "Rain Man" Dennehy, Ham Radio : EI5EDB (2m FM only) :-(
J.F. Engineering Undergrad, Internet  : [e-mail]
Trinity College Dublin.  Telepathy : [e-mail]

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Date: Tue, 23 Nov 1993 17:12:48 GMT
From: concert!news-feed-1.peachnet.edu!emory!kd4nc!ke4zv![e-mail]
To: [e-mail]

References <2cm8so$[e-mail]>, <[e-mail]>, <2crvn5$[e-mail]>
Reply-To : [e-mail] (Gary Coffman)
Subject : Re: single sideband generation

In article <2crvn5$[e-mail]> [e-mail] (Richard Karlquist) writes:
>In article <[e-mail]>,
>Gary Coffman <[e-mail]> wrote:
>>
>>>The non-correlation of interference is only worth 3 dB.
>>
>>I've seen this argued back and forth. It's true if you're just using
>>a summer as a correlator. But more advanced correlators are possible.
>
>That sounds very interesting.  Can you give us an more information
>about it?

Well it's tricky in the analog domain, but I've seen one circuit that
takes advantage of the common mode rejection of opamps to derive a
channel that has all the non-correlated noise and interference but
with the desired common signal suppressed by 60-80 db by the opamp's
common mode rejection. The anti-correlated signal is then inverted and
added back to the main channel, cancelling the undesired noise and
interference. Needless to say, the balance of this circuit is critical
to it's operation. It should be much easier to implement in DSP.
Note this technique assumes ISB detection as well since it requires
two separate audio channels. It's not a classic DSB detector.
If true IF DSP is available, this could all be combined into one
digital circuit.

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: 19 Nov 1993 00:39:49 GMT
From: dog.ee.lbl.gov!agate!howland.reston.ans.net!vixen.cso.uiuc.edu!sdd.hp.com!hpscit.sc.hp.com![e-mail]
To: [e-mail]

References <[e-mail]>, <2c8ohb$[e-mail]>, <2cg9h9$[e-mail]>
Subject : Re: single sideband

In article <2cg9h9$[e-mail]>,
Doug Braun <[e-mail]> wrote:
>This has been a fascinating discussion!  I have been reverse-engineering
>an old H-P vector impedance meter without benefit of the manual,
>and it does something very much like SSB generation.
>
>So: the question is:  What kind of circuit will take a RF signal
>anywhere between .5 MHz and 110 MHz, and generate a signal exactly 5KHz
>higher, with excellent spurious rejection?  It sounds like the SSB
>"phasing" technique, but with a single fixed audio frequency instead

No phasing techniques here.  It's just a .5 to 1 MHz. VCO with an
offset phase locked loop.  If this loop goes out of lock, the
"SEARCHING" light on the front panel lights up.  On ranges above .5 to 1
MHz., harmonics of the VCO are used.  This technique would be useless
for generating SSB voice signals.

Rick Karlquist N6RK
[e-mail]


>Doug Braun     Intel Israel, Ltd.      M/S: IDC1-41
>               Tel: [phone]   [e-mail]

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

Date: 23 Nov 1993 03:42:02 GMT
From: swrinde!sdd.hp.com!col.hp.com!news.dtc.hp.com!hpscit.sc.hp.com![e-mail]
To: [e-mail]

References <2brk68$[e-mail]>, <[e-mail]>, <[e-mail]>
Subject : Re: Phase-lock to WWV ?

>>His clocks at the NIST in Boulder are across the hall from the atomic
>>clock that is the primary standard, and run all the time.  They are
>>calibrated by the atomic standard, when it runs, which is relatively
>>seldom.
>>73, doug
>
>Oh no!  You mean the WWV clock I have heard for the last 20+ years aren't
>tied directly into the atomic standard?  I'm shattered, having had this image
>in my head for all this time of some titanium-hulled device on a marble slab
>in a sealed vault to which WWV clock was attached.  Funny how images like
>that, no matter how ludidrous, remain with us as long as there's no reality
>to displace them.
>
>  Kevin Sanders, KN6FQ                   |    ___    |

Let me try to shed some light on this.  First, you need to distinguish
between a usable clock that keeps time over long periods of time and
a laboratory frequency standard that measures frequency during the
occasional times when it is running.

The working clocks at NIST consist of a bunch of mainly HP 5061 and
5071 cesium atomic clocks, which are kept in controlled temperature
and humidity boxes.  Their time is averaged to get the official NIST
time, which is then averaged with other country's times and the US
Naval Observatory's time.  Worldwide Universal Coordinated Time
(UTC) is kept in Paris by the French equivalent of NIST (BIPM) and
is the average of the best 200 or so clocks in the world.

The laboratory frequency standards that fill a room, and are called
NIST-4, NIST-6, NIST-7, etc. are continually being improved upon
and run only occasionally for operational purposes.  They are used
to attempt to measure absolute frequency error in the on-line clocks.
The physics of the small on-line clocks limit the absolute frequency
accuracy to a few parts in 10 to the 13th while the lab standards
are known to be good to a few parts in 10 to the 14th.  Once the
error in the on-line clocks is known, it can be corrected for since
an HP 5071 is stable to a part in 10 to the 14th, for example.

Rick Karlquist N6RK
HP Santa Clara Division (where the HP5071 atomic clock is made)
[e-mail]

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

Date: 23 Nov 1993 03:23:17 GMT
From: swrinde!sdd.hp.com!col.hp.com!news.dtc.hp.com!hpscit.sc.hp.com![e-mail]
To: [e-mail]

References <[e-mail]>, <2cm8so$[e-mail]>, <[e-mail]>
Subject : Re: single sideband generation

In article <[e-mail]>,
Gary Coffman <[e-mail]> wrote:
>
>>The non-correlation of interference is only worth 3 dB.
>
>I've seen this argued back and forth. It's true if you're just using
>a summer as a correlator. But more advanced correlators are possible.

That sounds very interesting.  Can you give us an more information
about it?

>I understand that the doubler technique can be used with voice too.
>The time constant of the PLL has to be altered to a fast attack, slow
>decay curve. This may introduce a bit of distortion at the beginning
>of syllables if the attack timing is wrong.

This might be made to work after a fashion if you run the signal through
a delay line before mixing it with the recovered carrier so that the
PLL has a chance to lock up first.  Anyone know of any actual
experiments?

>Gary Coffman KE4ZV          | Where my job's going,  | gatech!wa4mei!ke4zv!gary

Rick Karlquist N6RK
[e-mail]

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End of Ham-Homebrew Digest V93 #112
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