Date: Sun, 6 Mar 94 04:30:29 PST
From: Ham-Equip Mailing List and Newsgroup <ham-equip@ucsd.edu>
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Subject: Ham-Equip Digest V94 #54
To: Ham-Equip
Ham-Equip Digest Sun, 6 Mar 94 Volume 94 : Issue 54
Today's Topics:
FT-530 vs TH-78A (2 msgs)
GPS Receiver Boards (2 msgs)
Help ID old SW Rcvr.?
MFJ SWR Analyzers (2 msgs)
Opinions on IC-2SRA?
Question about AZDEN PCS5000
Value of Yaesu 757GX II ??
Send Replies or notes for publication to: <Ham-Equip@UCSD.Edu>
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Problems you can't solve otherwise to brian@ucsd.edu.
Archives of past issues of the Ham-Equip Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-equip".
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: 28 Feb 94 02:36:47 GMT
From: agate!howland.reston.ans.net!cs.utexas.edu!news.tamu.edu!idmb-secretary.tamu.edu!user@ucbvax.berkeley.edu
Subject: FT-530 vs TH-78A
To: ham-equip@ucsd.edu
In article <1994Feb27.205456.5736@yvax.byu.edu>, sandersm@yvax.byu.edu
wrote:
> I am debating whether to buy a Yaesu FT-530 or a Kenwood TH-78A. I would like
> to know experiences of owners of both radios. I am new to this hobby and would
> appreciate any info. 73's TNX Chad
When I got my first HT last August, I also debated between these two
models. They are very similar in features, though the Kenwood has
alphanumeric display for paging I believe, and the Yaesu has built-in vox
(special headphone mike needed, though). I finally went with the Yaesu
mainly for ergonomic reasons. I thought the keypay was easier to use, the
Kenwood was a little small, plus the sliding door that covers the keypad
makes the bottom numbers hard to hit at times. The Yaesu is a little bit
bigger, but not much. Also, the Yaesu has the ability to scan for pl tones
being used on a repeater, so you can identify them and program them in.
I'm VERY happy with the Yaesu. I bought it even though it was a few
dollars more than the Kenwood at the store. However, I feel you can't go
wrong with either one. I almost bought the Kenwood myself, it took me about
20 mintues of handling them to figure out which one I liked best.
Troyce
KC5CBI
------------------------------
Date: 28 Feb 94 14:54:33 GMT
From: dog.ee.lbl.gov!ihnp4.ucsd.edu!swrinde!cs.utexas.edu!uwm.edu!fnnews.fnal.gov!att-in!cbnewsm!hellman@ucbvax.berkeley.edu
Subject: FT-530 vs TH-78A
To: ham-equip@ucsd.edu
In article <1994Feb27.205456.5736@yvax.byu.edu>, sandersm@yvax.byu.edu writes:
> I am debating whether to buy a Yaesu FT-530 or a Kenwood TH-78A. I would like
> to know experiences of owners of both radios. I am new to this hobby and would
> appreciate any info. 73's TNX Chad
>
The March issue of QST has a review of both radios (and other dual band HT's).
Shel Darack WA2UBK
------------------------------
Date: Fri, 4 Mar 94 18:34:14 GMT
From: ihnp4.ucsd.edu!ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!europa.eng.gtefsd.com!ulowell!xn.ll.mit.edu!ll.mit.edu!wjc@network.ucsd.edu
Subject: GPS Receiver Boards
To: ham-equip@ucsd.edu
In article <jyoungberg.1.000B87CC@draper.com>, jyoungberg@draper.com (James W. Youngberg) writes:
|> I've followed various GPS threads as they've come and gone. In order to pose
|> volume/price arguments to folks in the business, what would be the size of the
|> amateur market for GPS engines?
|>
|> Presume an engine consists of the entire RX, minus antenna, including a data
|> port (probably NMEA 0183), on a PC board. Examples are currently manufacured
|> by Rockwell, Magellan, Canadian Marconi, Plessey, and Trimble, among others.
|> Marketed in the $500 class for single-unit quantities.
|>
|> Skip, K1NKR
|>
How many channels would I get for $500?
Bill Chiarchiaro N1CPK
wjc@ll.mit.edu
------------------------------
Date: 4 Mar 1994 23:38:11 GMT
From: news.cerf.net!pravda.sdsc.edu!nic-nac.CSU.net!news.Cerritos.edu!news.Arizona.EDU!math.arizona.edu!noao!ncar!gatech!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!@ihnp4.ucsd.edu
Subject: GPS Receiver Boards
To: ham-equip@ucsd.edu
The Garmin GPS-10 receiver board is less than $350 in quantities of 2 (two). It is an 8-channel
receiver with NMEA output. They can supply a program that runs on a PC and displays the data
from the GPS-10, connected to one of the serial ports. The above price includes the antenna.
One of the reasons that we like it is that is only consumes 1 watt (0.2A @ 5V). Garmin can be
reached at (800)800-1020. Note that this is not an endorsement, etc., etc.....
Steven Hunter
------------------------------
Date: Fri, 4 Mar 1994 19:40:31 GMT
From: ucsnews!sol.ctr.columbia.edu!howland.reston.ans.net!europa.eng.gtefsd.com!news.msfc.nasa.gov!news.larc.nasa.gov!lerc.nasa.gov!news.uakron.edu!news.csuohio.edu!garfield.@@ihnp4.ucsd.edu
Subject: Help ID old SW Rcvr.?
To: ham-equip@ucsd.edu
Looking for help from some of you antique SW equipment buffs.
I have a shortwave receiver that my father purchased in England at
a flea market (on Portabello Road most likely, a well known area
for this type of thing), in the late 60's. We have had this thing
for about 30 years now, and it's darn near indestructible (it
survived ME melting crayons on the vacuum tubes as a kid).
I will describe the radio.
It appears to be of a military origin, perhaps WW II or at least
Korean war vintage, likely used by the British military because of
the markings which I will describe in a bit. However there is no
brand name to be found on it. It currently runs off 110v, but may
have been adapted from 240v which is used in England.
It has a black metal casing with heavy pressed indentations (for
rigidity in the sheet metal, probably). It's all vacuum tubes.
It's 17" wide, 8" tall, and 10" deep. A big radio, and weighs about
30 pounds. There are handles on either side of the front panel to
lift it. There are no rubber feet, but there are flush mounting
holes on either side of the cabinet, as if it could be mounted in
a rack. The front panel is held by 4 screws, and the entire unit
can be pulled forward out of it's metal housing for repairs. No
circuit boards, just tubes, RF chokes, big transformer, and plenty
of coils, caps, and resistors underneath the chassis, soldered all
over the place. All the tubes by the way are held in their sockets
with spring-loaded fiber baskets (probably asbestos or fiberglass
because of the heat). All the tubes look like they are wearing
little white knitted wool berets. Cute.
Miraculously, this thing works, and works well. The tuning is off
(i.e., WWV on 10Mhz dials in at 9.3Mhz), but it pulls pretty good.
Tuning is accomplished (analog of course) by an inverted-U shaped
plastic dial where all the slide-rule type ticks and frequencies
are printed (illuminated from above by 2 bulbs). The white pointer
(moves behind the plastic dial) is operated by a rather nice,
heavy crank flywheel tuning wheel, which can be locked in place by
a little lever. The needle sweeps in an arc between the 9:00 to the 3:00
positions. A humorous note - the lock-lever simply wedges
against the flywheel like a wheelchair brake. It's supposed to
lock the tuner onto a frequency, but the pressure on the flywheel
causes the thing to go out of tune because the tuning capacitor
plates shift slightly due to the pressure on the whole shaft
assembly by the lock mechanism. :-). Odd behavior for a radio that
is built like a steel vault.
It has 3 bands, controlled by a 3-way switch:
M.W.: (Medium-Wave, labelled in meters), from 200M to 550M. This
roughly corresponds to the usual AM broadcast band (545 - 1500Khz).
S.W.1: Labelled in "M c/s" (Megacycles per second, i.e., Mhz), from
about 2.3 Mhz to 7.5 Mhz.
S.W.2: Same as S.W.1., but from 7 Mhz to 23 Mhz.
On the dial, it gives you dots where BBC stations are supposed to
be on the M.W. band, and on the two SW bands it labels individual
meter sections for 120, 90, 60, 49, 41, 31, 25, 19, and 13 meter
bands. For example, I pick up CW and the garbled SSB of the 80
meter ham band about halfway between the 90 and 60 meter marks
(BTW, the unit is AM mode only, no CW or SSB).
More details:
Volume knob is labelled "GAIN". Two 1/4" plug jacks, labelled "2-
1/2 ohm loudspeaker" (no, not AM stereo :-) ). Knob labelled
"AERIAL TRIMMER" (which inside is a variable air-gap capacitor,
which seems to function as a sort of crude impedance matching
device. It does work with my random length wire antenna at various
freqs.). It is calibrated from "0" to "10".
There's a spring loaded "AERIAL" lug for bare wire, and two ground
lugs at either side of the unit for bare wire. These lugs could
probably be used to tie off an ore freighter they are so robust.
There's a "TONE" switch with "HIGH" and "LOW" positions.
There is a metal tag riveted on the front labelled "Mod Record"
with numbers in little boxes from 1 to 25. There is another metal
tag riveted on the front, which seems to have the most information
on it:
RECEIVER BROADCAST
P.C.R. No. 3 Mk. 1/2
ZA 30607 SERIAL No. R/RAC/PE/ 377
There are no other identifying marks, and nothing at all on the
chassis inside.
If anyone has heard of this type of shortwave radio, I'd love to
know the history behind where and when it may have been used.
Not looking to sell, just looking to know.
Thanks much,
Mike
--
^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v
Michael Mayer, Senior Technical Support Engineer Amateur Radio KB8RJO
Visual Numerics, Inc. 32915 Aurora Rd. Suite 160, Solon OH 44139 USA
Email: mayer@boulder.vni.com Human: 216-248-4900 Fax: 216-248-2733
v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^v^ Catch the WAVE v^v^v^
------------------------------
Date: 4 Mar 1994 05:39:07 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!torn!nott!uotcsi2!hassan@network.ucsd.edu
Subject: MFJ SWR Analyzers
To: ham-equip@ucsd.edu
Doug Braun (dbraun@scdtintel.com) wrote:
: In article <1994Mar1.162350.22173@ke4zv.atl.ga.us>, gary@ke4zv.atl.ga.us (Gary Coffman) writes:
:
: |> No. This only works if the antenna feed point impedance approaches
: |> the characteristic impedance of the coax most closely at resonance.
: |> That's roughly true for dipoles, but not for some other types of
: |> antennas. For example, a 1/4-wave monopole has a feed point impedance
: |> at resonance of about 36 ohms. At either side of resonance, the
: |> impedance (complex) increases. So there are two points where the
: |> impedance will be closer to 50 ohms than the resonant point.
: Although the impedance may be closer to 50 ohms, the SWR will
: INCREASE. Adding reactive impedance to a resistive load
: will NEVER decrease the SWR. Although the total impedance value
: may be closer to 50 ohms, the reactive-ness will just make the SWR worse.
: Stare at a Smith chart, and you will see this.
You are right in your statements but you are wrongly assuming that
the load is purely resistive. At least I know for monopoles and
dipoles it is rarely so over a broad range of frequencies. Feed
point impedance is complex and has both resistive and reactive
components. Cancelling the reactive part is one way of improving the
SWR but not necessarily to that of 1:1. SWR tuners do more than
cancelling the reactive part to make SWR of 1:1.
I'm very new in this field but I hope my explanation is O.K, :-)
hassan <<hassan@aix1.uottawa.ca>>
------------------------------
Date: Fri, 4 Mar 1994 17:22:36 GMT
From: mvb.saic.com!unogate!news.service.uci.edu!usc!elroy.jpl.nasa.gov!news.msfc.nasa.gov!europa.eng.gtefsd.com!howland.reston.ans.net!math.ohio-state.edu!sdd.hp.com!hp-cv!@@ihnp4.ucsd.edu
Subject: MFJ SWR Analyzers
To: ham-equip@ucsd.edu
Smitty, NA5K, (henrys@netcom.com) wrote:
: A general question: Can you dependably determine the resonance of an
: antenna by looking for the lowest SWR?
To which there has been quite a bit of discussion. I already posted a
to-the-point observation about that, but here's some more food for
thought:
Why do you necessarily _want_ to operate an antenna at resonance?
Case-in-point: consider a nominally 1/4 wave radiator above perfect
ground, something that can be approached at least with a good ground
radial system or a ground plane of wires or (automotive) sheet metal.
At resonance, the antenna looks like 30-something ohms (say about 36),
purely resistive. Below resonance, the resistive part of the feedpoint
impedance drops, and the impedance has a series capacitive reactance.
But above resonance (in other words, where the antenna is longer than
1/4 wave), the resistive part rises and the series reactance is
inductive. The resistive part increases smoothly, till we get to
antiresonance at about 1/2 wave long, where the resistance, highly
dependent on diameter/length ratio, will be in the vicinity of 1000 ohms.
That means that somewhere a bit longer than 1/4 wave resonance, the
resistive part must have passed through 50 ohms. If we can find that
point, then we need only put some capacitance in series with the
feedpoint to cancel out the inductive part of the antenna feedpoint
impedance, and we can get a perfect match to 50 ohms!
Now where might we find an installation where there's a ready-made
series capacitor? Well, consider thru-glass antennas on cars...if
we make the mounting plates the right size to get the right
series capacitance, it can exactly cancel the inductance of a
1/4 wave++ radiator. I believe this is quite practical for at least
2 meter installations. See the QST article on thru-glass antennas
from about May 93, I think; it doesn't explain _why_ the system works
well, but the thoughts here should help you get a better match if you
decide to use this system.
And in feeding a home-made vertical above a ground system on HF,
a variable cap at the base, in series with the feedline, seems like
about the simplest of matching networks.
73, K7ITM
------------------------------
Date: Fri, 4 Mar 1994 17:17:46 GMT
From: kgw2!tc_mac1.xetron.com!user@uunet.uu.net
Subject: Opinions on IC-2SRA?
To: ham-equip@ucsd.edu
Any opinions on the IC-23SRA (Icom 2m HT with 50-900MHz wideband receiver
built in)? Do comments about the R1 apply to this also?
--
Dave Steele
Xetron Corp.
------------------------------
Date: 4 Mar 1994 12:20:32 -0500
From: yale.edu!noc.near.net!genrad.com!genrad.com!not-for-mail@yale.arpa
Subject: Question about AZDEN PCS5000
To: ham-equip@ucsd.edu
Does anybody know how you find/replace the memory backup battery on
the AZDEN PCS5000 2 meter FM xcvr?
Thanks in advance.
Bill Ledder
wal@genrad.com
------------------------------
Date: 4 Mar 1994 20:29:17 GMT
From: ihnp4.ucsd.edu!ucsnews!sol.ctr.columbia.edu!newsxfer.itd.umich.edu!gatech!concert!bigblue.oit.unc.edu!samba.oit.unc.edu!not-for-mail@network.ucsd.edu
Subject: Value of Yaesu 757GX II ??
To: ham-equip@ucsd.edu
Hello All,
I have a friend who wants to trade me a Yaesu 757GX II in on a ham radio I
have. The radio has the matching power supply with it and both are in
excellent condition but I have no idea of the value of his equipment nor
how hard/easy it would be to re-sell. Any ideas?
Thanks,
Kenneth (WD4INE)
--
**********************************************************************
* The above does not represent OIT, UNC-CH, laUNChpad, or its other users. *
**********************************************************************
------------------------------
Date: 4 Mar 1994 19:08:14 -0500
From: news.cerf.net!pravda.sdsc.edu!nic-nac.CSU.net!news.Cerritos.edu!news.Arizona.EDU!math.arizona.edu!noao!ncar!newsxfer.itd.umich.edu!gatech!howland.reston.ans.net!noc.near.@ihnp4.ucsd.edu
To: ham-equip@ucsd.edu
References <CLn8o3.E4p@cbnewsm.cb.att.com>, <2kqskt$c3v@news.delphi.com>, <2kr49f$oaj@hp-col.col.hp.com>
Subject : Re: htx-202 audio mod (?)
bobw@col.hp.com (Bob Witte) writes:
[my original question deleted]
> Its unfortunate that the original poster referred to the deviation
> problem as a "mod". Most (all?) rigs have a deviation (modulation)
> adjustment. Apparently, RS was setting them too low on their
> early production units. So chances are today's radio is just like
> yesterday's except the adjustment is set differently.
I had read in another thread that there have been two versions of the radio,
the original, and then an update which was functionally the same, but had
some differences according to the schematic. Does anyone know where the
mod pot is located in case I need to adjust?
------------------------------
End of Ham-Equip Digest V94 #54
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