HAM Radio 3/hamradioversion3.0examsandprograms1992.iso/news/inham03/815.

Text File | 1979-12-31 | 15KB | 344 lines

INFO-HAMS Digest            Sat, 28 Oct 89       Volume 89 : Issue 815

Today's Topics:
                      Antennas 'Umbrella-shaped'
                     Down with SO239 connectors!!
                          Geomagnetic storms
                        Guemes Island followup
                              Hammurland
                info on Crystal Radio kit or schematic
                  Looking for comments on ham demos
                         Madison Electronics
                  Phone Patch Construction question
               Soldering PL259 connectors? Why bother!
----------------------------------------------------------------------

Date: Wed, 25 Oct 89 12:32:29 BST
From: Pete Lucas <[e-mail]> NERC-SWINDON
Subject: Antennas 'Umbrella-shaped'

Antenna that looks like a big inverted umbrella - looking in my ANDREW catalog
there are various versions of this - they are all broadband HF antennas
(typically 3-30MHz or 1.6-32MHz).  My book shows them with up to 160Kw
peak handling capacity, with a SWR of less than 2.0:1 throughout the
design operating range (envy envy...)
Wouldnt like to be in the room below a 160Kw transmitting antenna though!

They are omni-directional and known either as 'Spira-cone' or 'Mono-cone'
antennas (both being trademarks of Andrew Inc.  Orland Park IL)

The ANDREW catalog is worth browsing through - full of nice products
for professional/military applications HF through microwaves.
See if you can get your hands on a catalog - you will go green with
envy!!!!!!
Prices are as high as you would expect for 'professional' products though...
(shame, shame!)

                                   G6WBJ                    >-=Pete=-<

Please use the following addresses for reply:         +     \/Natural
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PHONE: [phone]                                 +  SWINDON SN1 1DE
FAX  : [phone]                                 +  GREAT BRITAIN

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

Date: Wed, 25 Oct 89 17:06:42 BST
From: Pete Lucas <[e-mail]> NERC-SWINDON
Subject: Down with SO239 connectors!!

Why, oh why, do manufacturers insist on fitting PL259/SO239 connectors
to their gear?  A more horrible connector for RF is hard to think of.
(anyone remember RCA Phono-plugs being used for RF wiring some years back?)
At anything above DC, the PL259 is horribly lossy and non-constant-impedance.
Unless you tighten them up real tight (like with a small pipe wrench!) they
unscrew themselves and oxidise after a few years.
The worst ones are the 'SO239-on-a-flying-lead' fitted to some of the
modern mobile rigs (and this at 144/430MHz too!!) which seem to plumb
new depths of flimsy construction.  Whilst we can't all afford to go for
'N' connectors at HF, anyone interested in long term reliability should
studiously avoid SO239 'UHF' types.  Specially avoid those where the center
insulator melts when you solder the inner. If you must use them, get ones
with PTFE insulation (which costs a bit more but stands solder temperatures
without melting away...) Long live BNC/TNC (specially above 30MHZ).
Try thinking of SO239's as 'screened test-prod connectors'.  Throw 'em out
and fit something 'constant impedance'.
Also, how come there seem to be two different threads on the SO239? Jap
and 'Rest-of-the-world' ?   They wont mate!

/////////////////////////////////////////////////////////////////////////
* The difference between Science and Religion is that with Science, you *
* do the experiment, then write the Book. With Religion, you write the  *
*         Book, then get someone to carry out the Experiment            *
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

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

Date: Wed, 25 Oct 89 07:17:20 EDT
From: Mike Owen W9IP <[e-mail]>
Subject: Geomagnetic storms

Responding to the questions about recent HF blackouts...
Yes, there have been several magnetic storms during
the past week.  The biggest was Saturday.  It was the
result of an X-13 flare (that means BIG).  A number of
other flares have been popping off the past couple of
days and a major storm is predicted for today (10/25).
This means a good chance for aurora on the VHF bands, and
stinko conditions on HF.
If you can't copy WWV, you can get the solar-terrestrial
report by calling [phone].

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

Date: 28 Oct 89 07:06:56 GMT
From: pilchuck!ssc![e-mail]  (Tad Cook)
Subject: Guemes Island followup


In Rick's posting:

>>
>> Tad, KT7H says:
>>
>> Actually, Rule 3b stands alone.  But if you choose to interpret it as
>> part of Rule 3a, the mileage figure is 75 miles, not 275 miles.
>> Guemes, in relation to Tatoosh, meets this test.  Butrule 3b

>Are you saying these two islands are more than 75 miles from the
>mainland?  My understanding was that you could actually see Guemes
>from the US mainland. That would be less than 75 milesnormally.

N6RK



Tad says:

Nope!  The islands are more than 75 miles apart.  That's what I meant
when I said "Guemes, in relation to Tatoosh".

But, of course this mileage test you mentioned is part of a DIFFERENT
rule.  Rule 3b SPECIFICALLY excludes any mileage test when it says "No
minimum distance is required".

Regarding where you can see Guemes from, you get there by a small ferry
that runs from Fidalgo Island across a narrow channel.  You can see
Guemes across the channel.


73,

Tad Cook
[e-mail]
KT7H @ N7HFZ

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

Date: Thu, 26 Oct 89 18:32:21 EDT
From: Joseph Skoler <[e-mail]>
Subject: Hammurland

Hi,
does anyone know anything about the Hammurland model FM 500C?
I wonder if it's a VHF amp - the input coils look too long
to be near 2 meter, looks more like 50 mhz.

Thanks for reading this.
-------------------------------------------------------------------
Joseph R. Skoler
skohc@cunyvm
[e-mail]
44.68.0.56]
---------------------------------------------------------------------

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

Date: Fri, 27 Oct 89 13:42:31 CDT
From: Will Martin <[e-mail]>
Subject: info on Crystal Radio kit or schematic

There's a place called Antique Electronic Supply that advertises in the ham
mags and in Radio-Electronics and Popular Communications. Here is an
address and phone for them that appeared on the net late last year:

Antique Electronic Supply
688 W. 1st St.
Tempe, Az 85281

[phone]

I have their catalog at home but no reference here so I can't verify
that this is current and correct info, but it should be a good starting
place even if it has changed.

They sell several different crystal radio kits, ranging from breadboard
types to ones in cases that emulate antique models.

Regards, Will

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

Date: Fri, 27 Oct 89 20:08:47 CDT
From: [e-mail] (Bob West - WA8YCD - DSEG/HRD Computer Systems Training - MSG HRD1 - 995-1908)
Subject: Looking for comments on ham demos

Yeah, Frank, I saw Phil's INFOHAMS posting. I gotta admit, I agree with him,
from a common sense attitude. You sometimes gotta trade off DRAMA (read that
HOLDING THEIR ATTENTION) for SAFETY (read that COVER YOUR OWN BEHIND)...

   (sarcasm mode engaged...)

:-) Maybe if you're in a hospital with a bunch of sick kids,
    it might not be a great idea, but hey, they got doctors
    and nurses there on the spot, right!?!

:-) Or maybe you could electrocute mice, just make all the kids
    sign an agreement that they won't leak it to the SPCA...

   (...end sarcasm mode)

I was a lecture demonstrator for a university physics department for a
while and we were always doing stuff to students, like making their hair
fly up with a vandeGraaf generator and making chains and having one hold
a flourescent tube and firing up the tesla coil...

If anything had happened, the university *could* have gotten into a
doozie of a lawsuit, but in the years I had the job, and the five or six
years my predecessor had it, and the fifteen or so years -his-
predecessor was on the job, there were no unhappy incidents. I suppose
we were (a) lucky and (b) too dumb to know better.

The more dangerous stuff, *I* got to do...

Of course, I did all kinds of dumb stuff as a kid, like setting off
firecrackers in a coffee can and pouring vinegar and baking soda in a
bufferin bottle and throwing it at the neighbor kid and I even got an
old neon sign transformer and made a jacob's ladder once. Safety? That
was for wimps, not me!

I didn't have any concept of that sort of thing then. But I sure had a
lot of fun!

A very good friend of mine in college was blinded and lost part of
his right hand by playing with fulmonate of mercury when he was a kid.
He *was* a ham and I had talked to him on the air for six months before
I knew anything about him. He went on to get his PhD in computer
science.

One thing I have noticed watching Mr. Wizard on Nickelodeon is he is
very safety conscious nowadays. He always makes the kids wear safety
glasses and tells them not to do the fire experiments unless a parent or
other adult is around. I *have* seen him burn wires and set hydrogen
balloons on fire and do some of the dramatic stuff, but always with a
care for safety.

It takes some of the excitement out of it. But it still makes the point.
Sort of.

Oh well, I suppose there *are* safe ways to learn. The problem you
pointed out, that kids today are jaded by star wars and high tech, is
one to keep professional educators on the ulcer medicine. I've seen
teachers who can naturally and comfortable engage students and many who
just throw up their hands and ride the wave.

Maybe a shock or two will wake them up.

73, and keep on smilin'!

Bob WA8YCD
 ______________________________________________________________________________
/ Bob West WA8YCD          | "I didn't know you were gonna do Social Studies!" \
| [e-mail] | "Whaddya mean? That was Kirchoff's Law!"          |
| [e-mail]   | "Yeah! CURRENT Events!"                           |
\__________________________|__________________________________________________/


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

Date: Thu, 26 Oct 89 07:37:07 EDT
From: Mike Owen W9IP <[e-mail]>
Subject: Madison Electronics

The question about Madison Electronics in Houston
reminds me of a slightly amazing thing that happened
to me there, long ago.  Max, the owner (SK?), answered a
question for me regarding biasing 813s.  The entire exchange
lasted less than three minutes.  He didn't know me, young high
school punk.  I returned to Madison's FOUR years later (not having
been there in between), and he instantly recognized me and asked
about the 813 amplifier.  What a memory.

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

Date: Thu, 26 Oct 89 18:29:50 EDT
From: Joseph Skoler <[e-mail]>
Subject: Phone Patch Construction question

Greetings,

If this msg has already reached the news group, please excuse.

I wonder if someone would take a moment and answer some not state-of-
the-art questions.  I am thinking about setting up a private phone
patch on 2 meters.  It would cover only about a 2 mile radius.

My first question concerns the legality and accpetability of this.
Of course, I would make certain the freq is not used by a repeater,
or packet or any other group.

Secondly, how cheaply can this be done.  I have a rig at home and an
old yaesu phone patch (model ll 301).  I assume I would hook up a vox
circuit on either the tel line or the radio line, but I wonder if it
poses a problem because it will be simplex.  I was thinking about getting
a subaudible tone decoder for the home station.  Also, would I need a tone
burst detector unit for control of various functions?

As you can see, I don't have much experience with this sort of thing.
Any suggestions and comments would be appreciated.

73,  Joseph Skoler,  kc2yu
SKOHC@CUNYVM
[e-mail]
44.68.0.56]

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

Date: Fri, 27 Oct 89 15:06:11 BST
From: Pete Lucas <[e-mail]> NERC-SWINDON
Subject: Soldering PL259 connectors? Why bother!

Why, oh why, do manufacturers insist on fitting PL259/SO239 connectors
to their gear?  A more horrible connector for RF is hard to think of.
(anyone remember RCA Phono-plugs being used for RF wiring some years back?)
At anything above DC, the PL259 is horribly lossy and non-constant-impedance.
Unless you tighten them up real tight (like with a small pipe wrench!) they
unscrew themselves and oxidise after a few years. They then get hot with RF!
The worst ones are the 'SO239-on-a-flying-lead' fitted to some of the
modern mobile rigs (and this at 144/220/430MHz too!!) which seem to plumb
new depths of flimsy construction.  Whilst we can't all afford to go for
'N' connectors at HF, anyone interested in long term reliability should
studiously avoid SO239 'UHF' types.  Specially avoid those where the center
insulator melts when you solder the inner. If you must use them, get ones
with PTFE insulation (which costs a bit more but stands solder temperatures
without melting away...) If you must use PL259, spend a bit more cash and
get good quality connectors (I can recommend Greenpar).
Long live BNC/TNC (specially above 30MHZ).
Try thinking of SO239's as 'screened test-prod connectors'.  Throw 'em out
and fit something 'constant impedance'.
Also, how come there seem to be two different threads on the SO239? Jap
and 'Rest-of-the-world' ?   They wont mate!

                                                            >-=Pete=-<


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

End of INFO-HAMS Digest V89 Issue #815
**************************************