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FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00005 Date: 09/26/97
From: IVY IVERSON                                           Time: 11:34am
\/To: JEFF EDMONSON                                       (Read 1 times)
Subj: High Gain Antennas for 2M

-=> On 09-27-97  06:13, Jeff Edmonson said to Ivy Iverson,<=-
-=>"About High Gain Antennas for 2M...,"<=-
-=> On 09-25-97  10:30, Jeff Edmonson said to Stan Black,<=-
 
Hi, Jeff;
 
 SB> I have made several yagis and quads for 2 meters.  I love antennas!
 
I love antennas, and I love playing (experimenting) with them!
 
 II> I do have an old CB SWR bridgs which I modified to be accurate on 2M.
 > ...
 JE> All those technical articles would be appreciated here, Ivy...  This
 JE> -is- after all, the HAM_TECH area <G>
 
Correctamundo!  That's why I pull it!
 
Any boy scout who can handle a soldering iron can do this one!   :-}
 
I have a dual-meter SWR bridge which was made for CB.  I haven't done
anything with CB for over 10 years, but I needed a SWR bridge for 2M.
So I proceeded to do the following:
 
There are supertech types who will dispute me on my method, but here is
how I modified a dual-meter CB SWR bridge to be pretty accurate around
150 MHz with reasonable sensitivity.  Do the same thing on both detectors:
 
  From directional     D1
  coupler:     --------|<-|------
                          |     |  Added mini pot, aprox 100K - 250K
(I could have done       ---    \
 a lot better if I    C1 ---    /
 had used high ASCII)     |     \
                        -----   / <--- To meter
                         ---    \
                          -     /
                                |
                              -----
                               ---
                                -
Modification: Add a mini pot, (salvaged from old equipment), of aprox
100 250 K or so.  Do this for both detectors.
 
Calibration: Feed the ANT side of the bridge into a load, (I used an
antenna with low SWR, but a 50 ohm dummy load would have been preferable).
Connect 2M HT to the XMTR side of the bridge.  Turn the bridge's CAL pot
to almost full sensitivity and apply RF from the HT.  Adjust the added
"Fwd power" pot for full scale deflection of the fwd power meter.
 
Then reverse the input and output RF connections to the bridge, (DO NOT
apply RF during this - DUH!), connecting the HT to the ANT connection,
and the load to the XMTR side.  Be careful NOT to change the setting of
the bridge's CAL setting during this procedure!  Again apply RF, and
adjust the added "Refl power" pot for full scale deflection of the SWR
(reflected power) meter.  The unit is now calibrated.  Reassemble the
SWR bridge and the modification is complete.  What could be simpler?
 
The modified bridge has since been checked using a known accurate 50-Ohm
dummy load, and the indicated SWR was aproximately 1.1:1, so it isn't far
from perfect.  (The 2-gang CAL pot in this particular individual unit
does not track very well, but it's plenty accurate for my purposes.)
 
-30-
 
And you're Welcome.   :-}
...
 
 II> I would LOVE to get my hands on the ARRL antenna book.
 
 JE> I've got an old 1950's version of it... GREAT info in there!
 
Want to get rid of it?  (Perhaps upgrade to a newer version?)  ;-}
If so, I would be glad to pay postage and maybe a few $$ for it if you
like.
 
73 DE KB9QPM
   Ivy
 
 
 
... Real HAMS do it till their Mega Hertz.
 
         -<Save BBSing from the Internet - Look for INTBBS_WK!>-
 
          ,-----> Ivy's WALL BBS  Home of Lakeshore Net <-----,
          |---------------> Ivy Iverson, KB9QPM <--------------|
          `-> Netmail me a request for info on Lakeshore Net <-'
 
___ Blue Wave/QWK v2.20 [NR]
--- TriToss (tm) 1.03 - (Unregistered)
 * Origin: Ivy's WALL BBS - Sheboygan, WI 920-457-9255 (1:154/170)
---------------

FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00006 Date: 09/26/97
From: IVY IVERSON                                           Time: 12:44pm
\/To: JEFF EDMONSON                                       (Read 1 times)
Subj: High Gain Antennas for 2M

-=> On 09-27-97  06:19, Jeff Edmonson said to Ivy Iverson,<=-
-=>"About High Gain Antennas for 2M...,"<=-
 
Hi, Jeff;
 
 JE> For example, would there need to be a shorting bar across the
 JE> resonant point of the "J" connection for the  directors?
 
 II> That's an interesting question.  Perhaps a 50 Ohm resistor?  (Like
 II> terminating a rhombic - the terminating resister has to absorb one
 II> half of the transmitted power, but it's presence controls
 II> the directional characteristics of the antenna.)
 JE> Now, just where are you going to find a 750 watt, 50 ohm resistor? 
 JE> };->
 
There are such things.  They are used in some commercial BC XMTRs.  They
don't have wire leads, they plug into a socket that looks like a large
fuse holder.  The resister itself looks very much like the carbon rods
used in #6 dry cells except they have metal caps on the ends.  IIRC, they
are called Glowbars.
 
HOWEVER, I really doubt that you would need resistors which approach half
the dissapation of the XMTR output.  That's for a rhombic antenna, which
is a horse of a different color, (or antenna of a different cut).   :-}
If a resister is needed in a J-pole array, I doubt it would have to
dissipate more than a few percent of the applied RF.  I could, of course,
be wrong.
 
 II> OTOH, say if you are using 2-element colinear 5/8 wave J-poles in
 II> an array, wouldn't simple 5/8 wave elements, (insulated?), + 5% for
 II> reflectors, and - 5% for directors be effective?
 JE> Probably, and as you said, it might look better, than all the J-pole
 JE> assemblies up there, but you just -never- know until you try, right?
 
RIGHT!  If I had the finances and equipment to measure the results, I
would be experimenting with this.
 
 JE> And, if it DOESN'T work, you've got some extra J-poles to give/sell to
 JE> other  hams there in the area, or Driven Elements for later Beam
 JE> Projects ;-) 
 II> It would be interesting to see what kind of insulators would
 II> be used between elements if it's a horizontal array!
 II> (Don't say, "Wooden dowls!")   :-}
 
 JE> Fiberglass Dowels? };->
 
Fiberglass or possibly nylon might work.  I would suggest a thick wall
tube rather than a solid rod, especially if the antenna is horizontally
polarized.  (A rod bends, but a tube has more bending strength because it
goes into compression and tension modes.)
 
I wonder what the RF characteristics the new carbon fiber materials have?
They are very strong, and should be able to support the weight, even when
mounted horizontally.
 
A 3-element, horizontally polarized, Co-linear J-pole beam anyone?   :-?
(Actually 12 active elements.)
 
           "=" is insulators.
 
       ----===----===O===----===----  Directors (4 insulated elements)
                     O
       -----=-----|--O--|-----=----- Driven J-poles (4 elements)
                ~~~  O  ~~~
      ------=------==O==------=------ Reflector (4 insulated elements)
 
If each J-pole has a gain of 6dB, and the director & reflector elements
are the usual 1/4 wave + and - 5%.  This should make a potent, if large,
beam for 2M or above!  (Can you imagine building one for 160M?)   };->
 
Question: How would the driven elements be phased?  I would think that
they would be fed 180 degrees out of phase.
 
Comments anyone?
 
73 DE KB9QPM
   Ivy
 
 
 
... Spread The Spectrum!!!
 
         -<Fido is dying!  QUICK!  Get the vet at INTBBS_WK!>-
 
          ,-----> Ivy's WALL BBS  Home of Lakeshore Net <-----,
          |---------------> Ivy Iverson, KB9QPM <--------------|
          `-> Netmail me a request for info on Lakeshore Net <-'
 
___ Blue Wave/QWK v2.20 [NR]
--- TriToss (tm) 1.03 - (Unregistered)
 * Origin: Ivy's WALL BBS - Sheboygan, WI 920-457-9255 (1:154/170)
---------------

FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00007 Date: 09/26/97
From: IVY IVERSON                                           Time: 03:36pm
\/To: JEFF EDMONSON                                       (Read 1 times)
Subj: High Gain Antennas for 2M

-=> On 09-27-97  06:30, Jeff Edmonson said to Ivy Iverson,<=-
-=>"About High Gain Antennas for 2M...,"<=-
 
Hi, Jeff;
 
 JE> Copper pipe J-Poles would fair better... maybe even some small (1/4")
 JE> tubing,  and do exactly that - if you were to feed them horizontally.
 JE> Probably better  suited for a vertical configuration.
 
 II> Agreed, though using solid pipes,
 JE> PArdon me, but "Solid Pipe" seems to be a contradiction in terms ;-) 
 JE> (Pipes  are hallow)
 
(Sorry for the oxymoron...)
 
 II> (I suggest something heavier than 1/4" however, like 1/2" to 1"),
 JE> Pipe?  Copper Pipe is intirely too heavy, and extremely large for
 JE> V/UHF work! 
 II> it should be possible to make a horizontal beam using J-poles.
 II> I'm not sure offhand if they would need to be fed in
 II> phase or 180 degrees out of phase. I'll have to think about that. :-/
 
 JE> I remember an antenna that was commerically made for 2m, by Cushcraft.
 JE> Had 4  driven elements, and they were cross-fed, so the last DE to be
 JE> fed, was 180  out of phase.
 
 JE> You see my message to Stan on Quagi's?  Why not 4 J-poles (two driven,
 JE> opposite of each other) two reflectors (same configuration) and yagi
 JE> directors?  Put the whole thing on a 20' wooden boom...
 
 II> Nope, missed that one.  Sounds interesting.
 
 JE> It's been pointed out, it might be a bit cumbersome...  but a pair of
 JE> 5/8  elements as DEs and yagi directors does sound reminiscent of a
 JE> Quagi. 
 
Hmmm... Not quite what I had in mind, but it might be quite workable.
I am more interested in something new that isn't in all the books, which
hopefully will have advantages, (like gain and/or directivity), over the
standard designs.  IOW, just experimenting with something different to
see how it compares.  If it works, great!  If it doesn't, try somethng
else.   :-}
 
73 DE KB9QPM
   Ivy
 
 
 
... Can't sleep?  Problem.  Are you a Ham?  NO PROBLEM!!!!  CQ-CQ-CQ... ;-{}
 
            -<Ask your host for INTBBS_WK and help save BBSing!>-
 
          ,-----> Ivy's WALL BBS  Home of Lakeshore Net <-----,
          |---------------> Ivy Iverson, KB9QPM <--------------|
          `-> Netmail me a request for info on Lakeshore Net <-'
 
___ Blue Wave/QWK v2.20 [NR]
--- TriToss (tm) 1.03 - (Unregistered)
 * Origin: Ivy's WALL BBS - Sheboygan, WI 920-457-9255 (1:154/170)
---------------

FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00008 Date: 09/26/97
From: IVY IVERSON                                           Time: 04:13pm
\/To: ROY WITT                                            (Read 1 times)
Subj: High Gain Antennas for 2M

-=> On 09-27-97  14:19, Roy Witt said to Ivy Iverson,<=-
-=>"About High Gain Antennas for 2M...,"<=-
-=> 25 Sep 97 00:55, Ivy Iverson wrote to Roy Witt:
 
 RW> Hello Ivy.
 
Hi, Roy;
 
 RW>> I built one a few years ago and it worked well.  The antenna
 RW>> itself is constructed using RG8 coax, cutting to 1/4 wave lengths
 RW>> and soldering them all  together in a vertical mode.  I put mine
 RW>> into a piece of PVC pipe and used it  for a while on my backup
 RW>> repeater that I keep in the garage.
 
 II> Do you have construction details for this one?  Would it be possible
 II> to get a copy from you?
 RW> You  guys are just bound and determined that I go home and look
 RW> through my  garage file cabinet...:)  Those plans are there somewhere,
 RW> along with the Quagi plans...
 
Yup.  (Pretty please?)   }:->
 
Seriously, wouldn't it be something like this, using electrical 1/4 wave
pieces of coax, (such as RG-8)?
 
        _______ _________ _________ _________ _________ _________
        -------/ /-------/ /-------/ /-------/ /-------/ /-------
        ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~~ ~~~~~~~
 
(I could do a better drawing with high-ASCII).
 
In other words, every electrical 1/4 wave, connect the center conductor
of the previous section to the shield of the next section and visa-versa?
 
 II>   It sounds like a good toy for field day or communication emergency
 II> situations.  (Got a weather baloon and a tank of helium?)   :-}
 RW> These are much more than field day or emergency antennas, their the
 RW> same basic  antenna you'll find on every mountain top,
 
Understood, but there aren't too many gain antennas that you can roll up
for storage.  And if you can hang it from a sufficently large balloon, you
would have one heck of a high antenna... how high is only limited only by
the length and strength of your coax.  Though if the wind is blowing,
you would probably have to anchor the balloon with guy lines.  The antenna
could serve as one of the guys, or could hang down under the balloon.
This is what UI had in mind with my previous statement... GREAT for field
day, emergencies or other temporary use.
 
 RW> whoops, sorry you don't have  mountains in Wisconsin, hilltop or
 RW> whatever repeater site.
 
Heh heh... Nothing that most people would call mountains, though there are
some darned high hills, like the one between here and Fon Du Lac, which
is only about 30-40 miles away, but it's rare to hit their repeater.
There is one Ham there that uses a beam and 25-50 Watts to hit our
county's main 2M repeater, and that's less than 20 miles from him.  Yet
I can reliably hit the big Milwaukee repeater, (nearest RX site about 40
miles from me), with only 5 watts and my 6dB J-pole.  (I have hit it
using a little twinlead J-pole when the band is open).  Nope, no
mountains, but plenty of hills.
 
 RW> Those white sticks you see at the Ham store are built the same way.
 RW> Take the  Hustler G6-440 I replaced it with.  Same antenna inside a
 RW> fiberglass tube. 
 
I'm not sure exactly what their internal construction is, but I'm sure
they are pretty standard, with 1/4 or 5/8 wave sections, properly phased,
no matter who made it.
 
73 DE KB9QPM
   Ivy
 
 
 
... Become hot stuff... learn to solder!   ;->
 
      -<Help save BBSing - Ask your host for INTBBS_WK today!>-
 
          ,-----> Ivy's WALL BBS  Home of Lakeshore Net <-----,
          |---------------> Ivy Iverson, KB9QPM <--------------|
          `-> Netmail me a request for info on Lakeshore Net <-'
 
___ Blue Wave/QWK v2.20 [NR]
--- TriToss (tm) 1.03 - (Unregistered)
 * Origin: Ivy's WALL BBS - Sheboygan, WI 920-457-9255 (1:154/170)
---------------

FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00009 Date: 09/28/97
From: ROY STARK                                             Time: 08:39am
\/To: ALL                                                 (Read 1 times)
Subj: Kenwood Tr-2500

Can anyone tell me what Voltage And Current to chg   a
battery pack for tr-2500(pb-26 pack).
any help i can get I thank you for.
Roy
--- Platinum Xpress/386/Wildcat! v1.3
 * Origin: FidoNet International Coordinator Emeritus, for life (1:202/746)
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FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH      Ref: EDY00010 Date: 09/28/97
From: JEFF EDMONSON                                         Time: 10:10pm
\/To: STAN BLACK                                          (Read 1 times)
Subj: antenna thingy

 > So, do I hook up the shield and center conductor to the so-239
 > in the normal way. And at the top, do I need a bare piece of
 > wire as a radiator?
Oh, Stan - you've -got- to learn how to quote messages.  I don't know what 
you're talking about, here...
 > That's what I need to figure out.  Don't want to be
 > cutting up my good coax for nothing!
I -think- you're talking about the multi-quarter wave lengths of RG-8, 
soldered together.  If so, then yeah - you'll have to find an SO-239 to feed 
it with.
   73 = Best Regards
   -Jeff KA5THB
   ka5thb@bigfoot.com
--- FMail 1.02
 * Origin: Electronic Avenue BBS 210-533-5668 San Antonio, TX (1:387/510)