The most interesting note here is the AM antenna was embedded in the
rear window. What car was this? I know they used to embed the antennas
in the windshield, but I've never seen anything in a rear window other
than the defroster strips
On 2/22/2017 6:12 PM, JP Pritchard via BVARC wrote:
Here's a related note having to do with broadcast car radio. I bought
a new car a few years ago and despite my pre-purchase test of the
radio, AM reception was almost entirely gone -- none existent after I
took delivery. Side note. Before taking delivery of the car, I had
the dealer install window tinting. I had a huge battle with the dealer
service department, trying to figure out what was wrong with the
radio. Through my own research, I discovered that the dealer had
subbed out the tint installation and that outfit had installed
metalically infused tinting. And since the AM antenna was embedded in
the rear window glass, it killed nearly all reception. It took quite a
while to get to the bottom of this, but the problem was solved when I
insisted on having that metalic tint removed and replaced with
something more conventional.
JP Pritchard,
KG3JPP
------------------------------------------------------------------------
*From:* BVARC [mailto:[email protected]] *On Behalf Of *Robert
Polinski via BVARC
*Sent:* Wednesday, February 22, 2017 5:36 PM
*To:* 'BRAZOS VALLEY AMATEUR RADIO CLUB'
*Cc:* Robert Polinski
*Subject:* Re: [BVARC] Paint and antennas (sometimes an insulator )
Years ago when I was doing Police car installations, I got a service
call that 2 Bellaire patrol cars had radio problems. Poor receive and
transmit. I open the trunk and put my Bird on the radio (UHF) and got
hi swr. Checking the cable all’s well, as I lowered the trunk lid I
observed someone had painted the antenna to match the car! These were
the plastic fin style you see on the trunk lids. Installed new
antennas, problem solved. The paint used was the same metallic blue
that was on the car. Proof that the metallic paint can affect the
antenna. I other cases I have used off the shelf paint like Krylon to
paint these same antennas (no metallic colors) with no effect on the
antenna. Robert
*From:*BVARC [mailto:[email protected]] *On Behalf Of *Jon
Livingston kb0mnm via BVARC
*Sent:* Wednesday, February 22, 2017 5:08 PM
*To:* BVARC, GMuller885--- <[email protected]>
*Cc:* [email protected]; Robert Polinski <[email protected]>
*Subject:* Re: [BVARC] Paint and antennas (sometimes an insulator )
Guys & Gals:
I will first echo what was said about metallic-flake paints,
lead-based paints, etc. because increasing the physical diameter of a
rod used in an antenna also can increase the bandwidth ( at the
expense of gain ).
For those portions of an antenna where a good electrical connection
is wanted, the above paints are not exactly right either. The problem
is that most metal paints actually stick better to slightly corroded
surfaces ( as long as they are not deeply perforated ) than to bare
metal. Accordingly, some use a slightly corrosive chemical to make the
initial bonding better. In order to get a shiny finish, the 'clear'
portion usually rises to the top and is non-conductive by comparison.
So even metallic paints can insulate to some degree, even though many
older ones have real metal flakes included.
One solution ( pun not really intended when talking about paints )
would be to prepare all the joints with emery cloth, clean the
surfaces of any remaining grit with a neutral solvent ( eg. rubbing
alcohol without the soap used in medicinal bottles or lighter fluid ),
and apply a conductive 'grease' to those surfaces.
What materials would fit the bill for conductive grease? This varies
according to what metals are involved. If you are dealing with
aluminum, you may wish to use the same grease that electricians use
for aluminum to copper wires in building construction- typically
clothes dryers. If you are dealing with an all copper ground, you may
wish to use a slight amount of "Butter it's Not" (Tm) which is
basically ground-fine copper and a 'secret' binder. Where lightning is
concerned, some folks would say that no chemicals should be used (
because a thick amount could be propelled by the heat if any water
were included ). Others might say that a 'Cold Galvanizing' paint
would be more appropriate because the zinc powder inside is combined
with an appropriate binder for contact with copper or other metals.
Larger two-way radio dealers get that paint from industrial chemical
and parts supply houses ( eg. Tessco )- which may require a minimum
purchase.
Once the intentionally-conductive surfaces ( like the inside and
outside mating of telescoping antenna tubes ) are coated, any
'non-conductive' paint could be used. I would recommend using a
quick-dry clear polyurethane prior to a color coat, in case the
'camoflage' were to be removed later.
Disclaimers:
1. All of the above statements are true to the best of my knowledge,
yet I do not sell paint for a living. My brother does, but he has not
been consulted on this an lives over 1,000 miles from Houston. For
best results, consult an electrician- or- make a sample and test for
yourself the conductivity on glass of any paint.
2. Statements made about paints sticking better to corroded surfaces
are in my experience true, given to me by a Master Electrician who
worked for Ford Motor at both the Assembly plant and Hydroelectric
facility in St. Paul, Mn. While I have every reason to believe that
this is true, you may wish to again consult a paint specialist.
3. "Gopher Grease" is one name loosely applied to a chemical used for
bonding aluminum to copper and other metals. Any electrical supply
house and most larger hardware stores should have this 'conductive'
grease on hand. It may cost you $15.00 to $65.00 for a small bottle,
thus shopping over the Internet may save you money.
4. Do not forget the words of Ralphie's mother in "A Christmas
Story(?)", when he asked for a BB gun- "You will put your eye out"-
this applies to working with the sharp ends of antenna tubes. Please
wear eye protection ( and nose protection ) if you paint with an
aerosol can & do so in a well-ventilated area.
.
*Jon L. Livingston, Electronics Technician*
17722 Fieldglen Drive ( SE of FM 529 & Barker Cypress Road )
Houston, Texas 77084
*[email protected]* <mailto:[email protected]>
**
General Radiotelephone license PGGB062294
CET Wireless Communications WCM-R185658
Amateur Radio license KB0MNM -73
www.linkedin.com/in/jon-livingston
<http://www.linkedin.com/in/jon-livingston>
------------------------------------------------------------------------
*From: *"Robert Polinski via BVARC" <[email protected]
<mailto:[email protected]>>
*To: *"BRAZOS VALLEY AMATEUR RADIO CLUB" <[email protected]
<mailto:[email protected]>>
*Cc: *"Robert Polinski" <[email protected]
<mailto:[email protected]>>
*Sent: *Wednesday, February 22, 2017 3:16:37 PM
*Subject: *Re: [BVARC] Paint and antennas
Paint is ok, do not use auto paint or metallic paint, or paint with
lead. Child safe paint assures no metals are used. No hi temp paints
ether. Another option is to use heat shrink tubing. Robert
*From:*BVARC [mailto:[email protected]] *On Behalf Of *Tom
Watson via BVARC
*Sent:* Wednesday, February 22, 2017 3:05 PM
*To:* 'BRAZOS VALLEY AMATEUR RADIO CLUB' <[email protected]
<mailto:[email protected]>>
*Cc:* Tom Watson <[email protected] <mailto:[email protected]>>
*Subject:* Re: [BVARC] Paint and antennas
Gayle,
I’ve been researching the exact same question, but have not found a
definitive answer. Some think it makes no difference; others are
skeptical. Below is an exchange I had recently with Al Andzik (WB0TGE)
about painting his “Mighty Woof” copper tube 2m/70 cm design (
http://www.hamradioschool.com/wbotges-mighty-woof-2m440-mhz-dual-band-fan-dipole/
). I am building this antenna and will test it with and without paint
by the end of March. I’ll post the results.
Tom Watson, WZ8Q
----------------------------------------------------------------------------
*From:*Al Andzik [mailto:[email protected]]
*Sent:* Friday, February 10, 2017 7:39 PM
*To:* Tom Watson
*Subject:* Re: Your "Mighty Woof" 2m/440 MHz fan dipole...
Really can't say if paint will affect characteristics. You might try
doing some SWR measurements un-painted then paint maybe one element
and see if things change. If they do, you can clean it off.
Also if a dark color is what you want, perhaps some "cold" gun bluing
solution might work instead of paint. You wouldn't have a coating over
the metal but it will just change the color. Usually the stuff is for
steel, but it might work on copper in some manner too.
On Feb 10, 2017, at 4:56 PM, Tom Watson <[email protected]
<mailto:[email protected]>> wrote:
Al,
Have you heard of anyone painting this antenna? I live in an
HOA-controlled area, but members of the architectural committee don’t
see so well and I believe that if I paint this antenna dark gray, no
one will see it. So far, I haven’t found any discussions that suggest
that an antenna cannot be painted or that doing so will cause a
significant decrease in performance. But I want to be sure before
proceeding with paint.
Also, I plan to run the transmission line inside a 15’, 1-3/8”
diameter steel tube attached to a wooden fence. Is it possible that
the tube will provide enough of a choke effect, or do you think the 4
or 5 turns of coax for that purpose will still be necessary?
Thanks again for your help,
Tom Watson, WZ8Q
*From:*BVARC [mailto:[email protected]] *On Behalf Of *Gayle
Dotts via BVARC
*Sent:* Wednesday, February 22, 2017 2:31 PM
*To:* BRAZOS VALLEY AMATEUR RADIO CLUB
*Cc:* Gayle Dotts
*Subject:* [BVARC] Paint and antennas
Can an tube antenna say a beam or Yagi, be painted for camoflage
purposes and not loose any Tx or Rx characteristics by painting it?
Gayle
KF5LVZ
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