QRZ! Ham Radio 5/QRZ Ham Radio Callsign Database - Volume 5.iso/digests/homebrew/940147.txt

Internet Message Format | 1994-11-13 | 13KB

Date: Wed,  1 Jun 94 04:30:19 PDT
From: Ham-Homebrew Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Homebrew Digest V94 #147
To: Ham-Homebrew


Ham-Homebrew Digest         Wed,  1 Jun 94       Volume 94 : Issue  147

Today's Topics:
                     Ham-Homebrew Digest V94 #129
                   need homebrew "recipes" (2 msgs)
                         SSB Filters (2 msgs)
                      Techno Whizzy DDS (3 msgs)

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We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
----------------------------------------------------------------------

Date: Wed, 25 May 1994 18:49:01 GMT
From: walter!NewsWatcher![e-mail]
Subject: Ham-Homebrew Digest V94 #129
To: [e-mail]

In article <[e-mail]>,
[e-mail] (Lyle D. Melton) wrote:
>
> In response to the question about telephone voltages in Europe....
>
>
> I just returned from a 3 yr stay in Italy and used our U.S. phones
> without problems.  If that helps... they are probably the same.
>
One thing to note about the European telephone systems, what works in one
country may not work in another.  While there are international standards,
they are not always implemented in every country.

"Typical" European values for telephone set operating parameters are:

Common Battery Voltage                 -48V dc
Operating Current                                        20 to 80 mA
Subscriber Loop Resistance 0 to 1300 Ohms
Loop loss                                                                        8 dB
Ringing Signal                                                    16 to 50 Hz, 40 to 130 V rms

These are basically the same as in the U.S.  Again, these represent
"typical" values and may vary among different European countries.

Another thing to think about is dialing.  Dual Tone Multi-Frequency (Touch
Tone) dialing is not very common, even in some of the more advanced
countries.  The pulse dialing in many countries is probably similar to the
U.S., but don't assume this is true everywhere.

Bottom line: Most U.S. phones using pulse dialing will work in most
European countries.

P.S. Notice that I didn't define Most ;-)

--
Daniel J. Connolly
[e-mail]
Bellcore
(These are my words, not Bellcore's)
--

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Date: Mon, 30 May 1994 20:18:20 GMT
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!howland.reston.ans.net!news.cac.psu.edu!news.pop.psu.edu!psuvax1!news.ecn.bgu.edu!feenix.metronet.com!pubcon![e-mail]
Subject: need homebrew "recipes"
To: [e-mail]

John, I've seen some good-looking projects (kits) for 2 meters and some
other bands by, of all people, JDR Microdevices in San Jose
(1-800-538-5000).  Looking through their catalog, they've got QRP
transmitter and receiver kits for 20, 40, and 80 meters; CMOS keyer
kit; packet radio kit; TV transmitter kit; 2-meter transceiver kit;
2-meter power amp kit.  And on and on.  Their BBS number is (408)
494-1430.

  Good luck!
Matt J. McCullar, KJ5BA

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

Date: Tue, 31 May 1994 21:55:38 GMT
From: spsgate!mogate!newsgate![e-mail]
Subject: need homebrew "recipes"
To: [e-mail]

In article <[e-mail]> [e-mail] (Matt
Mccullar) writes:
> John, I've seen some good-looking projects (kits) for 2 meters and some
> other bands by, of all people, JDR Microdevices in San Jose
> (1-800-538-5000).  Looking through their catalog, they've got QRP
> transmitter and receiver kits for 20, 40, and 80 meters; CMOS keyer
> kit; packet radio kit; TV transmitter kit; 2-meter transceiver kit;
> 2-meter power amp kit.  And on and on.  Their BBS number is (408)
> 494-1430.
>
I believe those are actually the Ramsey kits. Apparently they are now being
sold by JDR as well as directly from Ramsey.

Mark   AA7TA

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

Date: 31 May 1994 12:15:08 GMT
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!math.ohio-state.edu!jussieu.fr!univ-lyon1.fr![e-mail]
Subject: SSB Filters
To: [e-mail]

 Hello everybody !

 Thanks for your helping answers. I finally got a filter (in France) - 10.7
MHz with 2.2 kHz bandwith. It went with the lateral Xtals (10.6985 MHz in my
case). But I have taken note of the different addresses you gave me.

 The choice of the 10.7 MHz IF is not innocent. I am aware that one of the
problem when using packet radio is PLL locking time between RX and TX. It
takes about 200 ms, if your step is really small. By using a 10.7 MHz IF
for both TX and RX, I completly eliminate this problem, since the PLL remains
on the same frequency. I can also use a very cheap ceramic filter to filter
the FM.
 I know little about helicoidal filters, so I d be pretty interested in knowing
more. Also, I d like to know what frequency swing you can expect from a Xtal
oscillator modulated by a varicap diode.

 Many thanks again ! And 73 from F1RCS, Vince, QTH : Paris.

 Oh BTW,

: Have you considered a phasing sideband generator?

 Yes. BF shifter is a bit complex. Unless using a FIR to implement the
Hilbert filter.

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

Date: Tue, 31 May 1994 15:40:25 GMT
From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!news.dtc.hp.com!hplextra!hplb!hpwin055.uksr!hpqmoea![e-mail]
Subject: SSB Filters
To: [e-mail]

Elendir ([e-mail]) wrote:

:  I know little about helicoidal filters, so I d be pretty interested in knowing
: more.

  Connaisez-vous  "Handbook of filter synthesis" par Anatol I Zverev,
John Wiley and sons inc New York 1967  ISBN 0 471 98680 1   ?
chapitre 9 "Helical filters" . c'est le tome definitif pour le dessein
mathematique des filtres.

 Also, I d like to know what frequency swing you can expect from a Xtal
: oscillator modulated by a varicap diode.

  (sorry, my French isn't adequate for this part..)

   It depends a lot on the frequency, the circuit, and production
tolerences. With care a 200 ppm (parts per million) tuning range can be
reasonably reliably achieved for a favourable frequency and circuit.

  beware that overtone crystals are far far harder to pull. In general
terms, if you have two crystals at the same frequency, the overtone one
will give a swing reduced by a factor roughly equal to the square of its
overtone number.

   Example:

      A 25 MHz fundamental crystal in an oscillator circuit with a swing
of 100 ppm.  replace the crystal with one with its third overtone at 25
MHz, and you'll get about 100/(3^2) = 11 ppm swing !  (very roughly!)

  If the tuning range is important, use a funamental crystal at a
suitable frequency, and use frequency multipliers.

  Beware of attempts to pull an oscillator too far, you'll suffer from
temperature dependant failure to start, etc etc.

   Bon chance

             David   GM4ZNX

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

Date: 31 May 1994 02:18:26 GMT
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!usenet.ins.cwru.edu!eff!news.kei.com!hookup!news2.sprintlink.net!news.sprintlink.net!indirect.com![e-mail]
Subject: Techno Whizzy DDS
To: [e-mail]

Ferraro14 ([e-mail]) wrote:
: Is anybody expirimenting with the techno whizzy dds or any other DDS.

I'm building a PC-based DDS around the Qualcomm DDS - when I get the time
to work on it :(  Board is designed and half wired.

Pat

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

Date: 31 May 1994 08:56:28 -0700
From: nntp.crl.com!crl2.crl.com![e-mail]
Subject: Techno Whizzy DDS
To: [e-mail]

In article <2se6pi$[e-mail]> [e-mail] (Patrick Berry) writes:
>Ferraro14 ([e-mail]) wrote:
>: Is anybody expirimenting with the techno whizzy dds or any other DDS.
>
>I'm building a PC-based DDS around the Qualcomm DDS - when I get the time
>to work on it :(  Board is designed and half wired.
>
>Pat
>

I really hope that you don't keep this all to yourself! 8-)  I have wanted to
do one of those for quite a while. What has your costs been so far? How much
is the Qualcomm DDS and where did you get it? Thanks for any info you can
give me!

Jeff
AB6MB

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

Date: Tue, 31 May 1994 09:36:27 GMT
From: lll-winken.llnl.gov!overload.lbl.gov!agate!howland.reston.ans.net!math.ohio-state.edu!sdd.hp.com!hpscit.sc.hp.com!news.dtc.hp.com!hplextra!hplb!hpwin055.uksr!hpqmoea![e-mail]
Subject: Techno Whizzy DDS
To: [e-mail]

Ferraro14 ([e-mail]) wrote:
: Is anybody expirimenting with the techno whizzy dds or any other DDS.
: Has any body read the two tech articles in QST by Rohde on receivers


    No, yes, both.




    But seriously...   Have you seen the data on the various Qualcomm
devices, and those from Analog Devices ?   The AD7008  seems to be THE
device now.  I've got one running on its demo board.


    Ulrich Rohde's articles are very important, but I wonder whether
they will be fully appreciated. He is exactly right about the very poor
distribution of gain in the usual Japanese transceivers, and the effect
it has on receiver performance. As the bands become more crowded and the
adjacent broadcasters buy still more watts, this will become even more
important. The existing radios seem to have their gain profile planned
to minimise the need for internal screening above all other
considerations.

    He suggests a low frequency DDS with a PLL frequency multiplier
following it. This has some good points, and some bad ones.  A DDS
alone, like the Technowhizzy, can work nicely as a transmitter but runs
into problems in a receiver. DDS quantising noise terms will be 60-70dB
down on the output signal, and will be present at various frequencies
over (and a little beyond due to limitations on practical filters) the
full tuning range of the DDS. The exact frequencies of these quantising
components will move around as you tune the DDS.  Putting a PLL between
the DDS and the receiver structure, either in a multiplicatice role as
Rohde suggests, or in an additive structure as done in current
production radios will impose a tracking filter effect on the LO, which
will remove quantisation components that are outside the loop bandwidth
(usually kHz to at most tens of kilohertz)
    The worst case is if we tune the DDS to a frequency where its output
is close to a quantisation component - close enough to pass the PLL. The
true input to the PLL is the vector sum of the DDS wanted output AND the
quantisation component. The difference in their frequencies and the
amplitude limiting effect of the PSD in the PLL will let this be treated
as a phase-modulation sideband. The PLL will pass this phase modulation.
In an additive system, the component is passed to the receiver LO signal
at its same strength relative to the wanted signal. In a multiplicative
system, the PLL multiplier will multiply the phase modulation, giving an
unwanted output 20 log (N) dB higher than before (N is the freq
multiplication factor for the PLL)
    This does not rule out such systems, but it does point out that DDS
quantisation is more critical, and some art is needed in the choice of
frequency ranges to try to avoid the very worst cases, if possible.

    Rohde is right, the system he suggests is simple and elegant. For an
upconverting radio, the LO needs to cover less than an octave, so a
fixed ratio PLL is OK, which allows better loop design as the effects of
variable N need not be allowed for.  With the current progress of
creating better and better high speed DACs, I think it may be the way to
go.  If a new DAC offers better resolution and glitch energy, the
quantisation components will be reduced. If a new DAC offers faster
speed for the same quantisation component levels, then the PLL can be
designed with lower N, and so reducing the multiplication factor, thus
making a cleaner LO.

   The thing to beware of is that these systems look fine at some
frequencies, and only produce problems at a few regions.

  Cheers
         David  GM4ZNX



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End of Ham-Homebrew Digest V94 #147
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