QRZ! Ham Radio 5/QRZ Ham Radio Callsign Database - Volume 5.iso/digests/homebrew/940059.txt

Internet Message Format | 1994-11-13 | 9KB

Date: Sun, 13 Mar 94 04:30:32 PST
From: Ham-Homebrew Mailing List and Newsgroup <[e-mail]>
Errors-To: [e-mail]
Reply-To: [e-mail]
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Subject: Ham-Homebrew Digest V94 #59
To: Ham-Homebrew


Ham-Homebrew Digest         Sun, 13 Mar 94       Volume 94 : Issue   59

Today's Topics:
                    Best cars for mobile HF/VHF??
     Classified Ads (was Re: For sale: 1300 nm (IR) laser diodes)
                        Duplexer design info?
                Looking for plans/kits..VHF CW/SSB QRP
                     Ramsey SA-7 broadband preamp
                          Two Unknown Chips

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Problems you can't solve otherwise to [e-mail].

Archives of past issues of the Ham-Homebrew Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew".

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: 12 Mar 1994 15:36:12 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!europa.eng.gtefsd.com!news.umbc.edu!haven.umd.edu!cville-srv.wam.umd.edu![e-mail]
Subject: Best cars for mobile HF/VHF??
To: [e-mail]

In article <[e-mail]>,
Gary Coffman <[e-mail]> wrote:
>Look at what the cops are driving.

Good idea, Gary.  Just don't forget to leave off the whitewalls!

-N3NKI

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Date: 12 Mar 1994 20:17:59 GMT
From: ihnp4.ucsd.edu!swrinde!elroy.jpl.nasa.gov!ncar!hsdndev!dartvax.dartmouth.edu![e-mail]
Subject: Classified Ads (was Re: For sale: 1300 nm (IR) laser diodes)
To: [e-mail]

     Since I seem to be seeing a rash of classified ads in this
newsgroup lately, I think it's time to point out that for sale/wanted
posts belong in rec.radio.swap and rec.radio.swap _only_.  Please
refrain from posting classified ads here.

---
=======================================================================
Kenneth E. Harker  N1PVB        Dartmouth College  Amateur Packet Radio
[e-mail]  Hinman Box 1262    [e-mail]
[phone]                  Hanover, NH 03755  or n1pvb-5 on 144.99
=======================================================================
             (PGP Public Key now available on request)

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

Date: 12 Mar 94 23:23:53 GMT
From: [e-mail]
Subject: Duplexer design info?
To: [e-mail]

In browsing various publications, appears modern VHF/UHF duplexer design is
a product of the black art.  I'm in the process of cutting down an old
DB Products band-pass 2M duplexer for 220 MHz.  This duplexer has coupling
loops in each cavity.  My references don't discuss  whether there is an
optimum coupling loop shape factor Vs frequency.  Nor is anything
mentioned whether the lengths of the cavity coaxial connecting lengths are
critical.  One commercial reference cautions field technicians from modifying
the coaxial harness, stating to do so will cause deteriation of duplexer
performance.

Whilst the cavities are apart, it would be nice to modify them for band-
reject operation as well.  Again, my references are silent on this topic.

Anyone on the net willing to share their practical experience/guidance about duplexer design?

73 de Jack

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Date: 12 Mar 1994 22:30:34 GMT
From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!gag.com![e-mail]
Subject: Looking for plans/kits..VHF CW/SSB QRP
To: [e-mail]

Gary Coffman ([e-mail]) wrote:
: Look at the two part feature in recent QSTs describing Rick Campbell's
: SSB rig. It will work on any frequency up to 70 cm.

I sent an SASE asking for more info to the supplied address a couple of
months ago, but have heard nothing back... was I unlucky?  Time to try again,
I suppose.

73 - Bdale, N3EUA

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Date: 13 Mar 1994 00:38:15 GMT
From: ihnp4.ucsd.edu!agate!usenet.ins.cwru.edu!cleveland.Freenet.Edu![e-mail]
Subject: Ramsey SA-7 broadband preamp
To: [e-mail]

In a previous article, [e-mail] (Eric Matthews) says:

>
>Hello.
>
>I would like to know if any of you here on r.r.a.h have assembled
> and used the Ramsey SA-7 preamp.
>I am planning to get a few of them and use them for TV and FM DX.
>I will have one for FM, one for UHF, and one for VHF.
>I have three seperate antennas for those bands, and seperate feed
>lines too.
>
>Will it be difficult to design a filter system where only the de
>esired band(ie FM, or UHF TV) get amped by the SA-7?
>
>I plan on buying three of them, and I would like to know what I
>am getting into before I plunk down the $$$.
>
>By the way, here are some specs:
>
>freq range:100kHz to 1000mHz
>gain:>20dB
>noise figure: < 4dB
>NEC microwave transistors are used in the design.
>They are $14.95 each in kit form from Ramsey.
>Ramsey is at: [phone]
>
>
>
>Thanks.
>--
>Eric Matthews
>[e-mail]
>

I used one for my 6 meter rig and it works.  According the the instructions
you can tune it for a desired frequency by adding a tuned circuit before
and after the preamp....
--
Ronald Wolenski   [e-mail]
N8WCR
Parma, Ohio

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Date: 13 Mar 94 05:48:10 GMT
From: [e-mail]
Subject: Two Unknown Chips
To: [e-mail]

Hi,

I'd like to get a little info on two chips I've run across.  One is an
NEC B571C, 8 pin DIP (so I know it's not the Signetics compandor).  I
think it's a prescaler for a PLL.  The other is a (Plessey?) PSSR
SL560C, 8 pin DIP, which may be an IF amp.  I'm hoping to get enough
of a description of these to decide if they might be fun to play with.
Thanks for any info.

73,
Mike, KK6GM

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

Date: 12 Mar 1994 22:27:29 GMT
From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!gag.com![e-mail]
To: [e-mail]

References <2lh20r$[e-mail]>, <[e-mail]>, <[e-mail]>
Subject : Re: GPS Receiver Boards

[e-mail] wrote:

: I've sent for the specs from Motorola...

: If the product is up to snuff...

I've worked with, or have friends who have worked with, the Rockwell, Trimble,
and Motorola receiver cores.  Concensus is that the Motorola core is the best
for time-transfer applications.  The Trimble has a well-defined but annoying
jitter to the 1pps signal, the Rockwell gives a 1pps signal that is precise
and fairly stable but not aligned with the edge of a second, complicating
host software.

All give good results for position and velocity applications.  If you want to
fly them on weather balloons and such, the Motorola behaves best, holding the
last valid position when you hit the COCOM restriction height, the Trimble
resets to their corporate offices in CA, reportedly.  I don't know anyone who
has flown a Rockwell in this application.

The Rockwell has a GaAs frontend so can work well with non-amplified patch
antennas over short coax runs.  The Trimble and Motorola units benefit from
an amplified patch or better antenna.

In summary, if ya gotta do a group purchase, go with the Mot units, and if the
price is good, I know a dozen or so folks (working on the AMSAT P3D GPS
project) who are likely to be interested in buying one to play with.

73 - Bdale, N3EUA

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

Date: 13 Mar 1994 00:12:27 GMT
From: ihnp4.ucsd.edu!swrinde!elroy.jpl.nasa.gov!nntp-server.caltech.edu![e-mail]
To: [e-mail]

References <[e-mail]>, <[e-mail]>, <2ltfkh$[e-mail]>
Subject : Re: GPS Receiver Boards

[e-mail] (Bdale Garbee) writes:

>All give good results for position and velocity applications.  If you want to
>fly them on weather balloons and such, the Motorola behaves best, holding the
>last valid position when you hit the COCOM restriction height, the Trimble
>resets to their corporate offices in CA, reportedly.  I don't know anyone who
>has flown a Rockwell in this application.

Apparently the restriction is only required when you exceed certain
altitude AND speed limit simultaneously.  Our group has successfully
used GPS (the Rockwell card, I am ~90% sure) on scientific balloons
(~125,000 feet, but typically much less than a hundred miles per hour).
We were warned that early versions of the board we used would not
work, because it unnecesarily restricted at either a certain altitude
OR speed limit.

Contact the companies for futher details.
--
        David M. Palmer        [e-mail]
                    [e-mail]
    Clipper: Privacy for people who have nothing to hide.

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End of Ham-Homebrew Digest V94 #59
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