Re: The GND screw on a SW Radio
Brenda Ann
wrote in message news:qv1lh6lpgj29mtl24...@4ax.com...
Seems all the older tube SW radios had a GND (ground) screw by the ANT
(antenna) screw. Does connecting this ground screw make the antenna
receive better, or is it just for lightning protection? Or maybe it's
not needed at all, but I'd think it's there for some reason. I have
not seen this on modern portable SW radios, but seems they just rely
on a rabbit ear antenna, which is not very effective.
If this ground does serve a purpose, what's the best thing to connect
it to? Separate dedicated ground rod, or just connect it to any metal
water pipe or the house electrical system's ground (such as a grounded
outlet box).
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It does help, more on the lower bands than the upper, but some on all bands.
Definitely NOT lightning protection, as even a near strike would fry the
front end of the radio.
Most modern portables either have a coaxial antenna input, which has a
ground connection, or no external antenna connection at all.
As for good grounds, separate ground spike is best, with a cold water pipe
(not hot water nor gas line) being a runner up. Using the ground lug on an
AC outlet may "work", but it's not a good idea.
D. Peter Maus
>
> What about connecting to the same ground rod the house panel connects
> to? Or would that introduce AC hum?
Code recommends it. Requires in some instances that your RF
ground also be bonded to the mains ground. The better solution would
be to run a separate ground system. A 12' ground rod away from the
building, bonded through a copper strap to the A/C ground, is a good
start.
Myself, I run an 8' ground rod every 10 or 15 feet circling at a
distance from the house, bonded together with a 4 inch braided
copper strap, bonded to the head end of the transmission line. With
the transmission line bonded again, to a 12'ground rod just before
entry into the building. That rod is also bonded to the mains ground.
A very quiet set up for listening. This also insures that the
antenna, transmission line, and the radios all operate at the same
reference to ground, so in the event of a near-strike, everything
lifts simultaneously, reducing the risk of discharge through the
front end.
>
> Just curious. On a modern radio, (without a coax connector), if I was
> to connect a 50ft. (or more) outdoor wire to the rabbit ear using an
> alligator clip, would that give better reception?
It may. It's just as likely, especially on a portable, to
overload the front end, creating artifacts up and down the dial, and
if there is a local strong enough, damage your input transistor.
>
arthr...@webtv.net
> On 12/28/10 20:02 , farme...@nowhere.com wrote:
>
>
>
>
>
> > On Wed, 29 Dec 2010 10:44:52 +0900, "Brenda Ann"
>
> >> wrote in messagenews:qv1lh6lpgj29mtl24...@4ax.com...
>
> >> Seems all the older tube SW radios had a GND (ground) screw by the ANT
> >> (antenna) screw. Does connecting this ground screw make the antenna
> >> receive better, or is it just for lightning protection? Or maybe it's
> >> not needed at all, but I'd think it's there for some reason. I have
> >> not seen this on modern portable SW radios, but seems they just rely
> >> on a rabbit ear antenna, which is not very effective.
>
> >> If this ground does serve a purpose, what's the best thing to connect
> >> it to? Separate dedicated ground rod, or just connect it to any metal
> >> water pipe or the house electrical system's ground (such as a grounded
> >> outlet box).
>
> >> --------------------------------------------------------------------------------
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
His tube radio will survive !
RHF
- Seems all the older tube SW radios had a GND
- (ground) screw by the ANT (antenna) screw.
That they do.
You Hallicrafter S107 has two (2) Antenna Screws
A1 & A2 for 300 Ohm [TV] Twin-Lead or Ladder-Line
http://www.packetradio.com/catalog/index.php?main_page=product_info&products_id=1776
+plus+ A Ground Screw with a Shorting/Jumper
Link/Wire between A2-to-G
http://pcbunn.cithep.caltech.edu/jjb/Hallicrafters/S107/IMG_3069.jpg
You could use a Dipole Antenna with it using
http://www.hamuniverse.com/hfdoublet.html
http://www.wb0smx.net/wp-content/uploads/2009/07/80_meter_doublet.jpg
http://www.deltadx.net/ABCDx/Sections/Images/Antennas/Dipole-Ladder2.gif
300 Ohm [TV] Twin-Lead as a feed-in-line
http://www.electronicplus.com/images/products/COL300B.jpg
-note- Remove the Shorting/Jumper Link/Wire
between A2-to-G when using a Dipole Antenna
with a Twin-Lead feed-in-line.
But still use an earthen Ground connected to
the "G" Screw.
.
- Does connecting this ground screw make
- the antenna receive better,
Almost all of the time with a good Antenna
and a good earthen Ground : YES !
.
- or is it just for lightning protection?
Yes - It is also used for Lightening Protection.
.
- Or maybe it's not needed at all,
Yes - It Is Needed.
- but I'd think it's there for some reason.
Yes for both an Antenna Ground
and a Safety Ground.
- I have not seen this on modern portable SW radios,
Most of the time a 'portable' AM/FM Shortwave Radio
uses Batteries, and the Radios are NOT connected to
the House AC Electrical System; plus just using the
built-in Whip Antenna. {Floating/Isolated}
- but seems they just rely on a rabbit ear antenna,
- which is not very effective.
The Radio's Whip Antenna is reasonably effective
for it's size.
- If this ground does serve a purpose,
what's the best thing to connect it to?
A good earthen Ground using an 8-Foot Ground
Rod and Heavy #10 AWG Copper Ground Wire.
- Separate dedicated ground rod, or just
- connect it to any metal water pipe or the
- house electrical system's ground
- (such as a grounded outlet box).
A good earthen Ground using an 8-Foot Ground
Rod and Heavy #10 AWG Copper Ground Wire.
- Thanks
hope this helps - iane ~ RHF
.
.
dave
plate of a capacitor. You need to use metal to complete the capacitor.
Wire radials, poultry netting, salty bogs, have all been used. An 8'
ground rod driven vertically is pretty useless for improving an antenna
system.
dave
>
> Thanks for the reply
>
> What about connecting to the same ground rod the house panel connects
> to? Or would that introduce AC hum?
>
> Just curious. On a modern radio, (without a coax connector), if I was
> to connect a 50ft. (or more) outdoor wire to the rabbit ear using an
> alligator clip, would that give better reception?
>
No You will cause the front end to go non-linear and produce unwanted IMD
dave
>
> His tube radio will survive !
Tube radios don't have "rabbit ears"
sctvguy1
> Myself, I run an 8' ground rod every 10 or 15 feet circling at a
> distance from the house, bonded together with a 4 inch braided copper
> strap, bonded to the head end of the transmission line. With the
> transmission line bonded again, to a 12'ground rod just before entry
> into the building. That rod is also bonded to the mains ground.
How do you mow the yard with all of that grounding equipment?
I connect to the cold water pipe by running the wire low to the
outside wall so the yard guy won't run over it with the mower.
D. Peter Maus
> On Tue, 28 Dec 2010 22:56:18 -0600, D. Peter Maus wrote:
>
>
>> Myself, I run an 8' ground rod every 10 or 15 feet circling at a
>> distance from the house, bonded together with a 4 inch braided copper
>> strap, bonded to the head end of the transmission line. With the
>> transmission line bonded again, to a 12'ground rod just before entry
>> into the building. That rod is also bonded to the mains ground.
>
> How do you mow the yard with all of that grounding equipment?
Everything's buried. The rods are driven to 1' below the surface.
bpnjensen
This can be successful if the lead in wire remains insulated, and you
wrap the *insulated* wire around the whip a few times for an inductive
connection. You can adjust the sensitivity quite nicely this way
depending on how may coil wraps you use.
arthr...@webtv.net
> On 12/28/2010 09:19 PM, arthrny...@webtv.net wrote:
>
>
>
> > His tube radio will survive !
>
> Tube radios don't have "rabbit ears"
Read D.Peter Maus' post again. My responce was in reference to his
last sentence. And when someone invents or discovers a SW radio with
rabbit ears ,please let us know.
RHF
Some/Many old 'portable' AM/FM "PB" Shortwave
Radios has Two Whip Antennas for FM and PB.
http://www.radiotimeline.com/ar-zenithRoyal2000.jpg
http://www.radiotimeline.com/ar-RadioShack-sw60.jpg
http://www.radiotimeline.com/radioshack-1973_Astronaut8.jpg
-not- exactly Rabbit Ears -but- Two Whip Antennas
http://cgi.ebay.com/Century-Mark-IV-Multi-Channel-Transistor-Radio-/230567394758
http://cgi.ebay.com/Vintage-Old-Solid-State-Transistor-Musicair-Radio-/310280181630
http://cgi.ebay.com/RADIO-AIRCASTLE-3-band-AC-DC-solid-sta-Vintage-portable-/160524527047
http://cgi.ebay.com/RADIO-Masterwork-6-BAND-transistor-world-wide-shortwave-/160519432360
RHF
> On Wed, 29 Dec 2010 10:44:52 +0900, "Brenda Ann"
>
>
>
> <newsgro...@fullspectrumradio.org> wrote:
>
>
> What about connecting to the same ground rod the house panel connects
> to? Or would that introduce AC hum?
>
- On a modern radio, (without a coax connector),
- if I was to connect a 50ft. (or more) outdoor wire
- to the rabbit ear using an alligator clip,
- would that give better reception?
! 'rabbit ear' !
Actually you point something out that the
Hallicrafter S107 has Two (2) Antenna Screw
Terminals A1 & A2 for 300 Ohm [TV] Twin-Lead
a/o Ladder-Line for an Antenna feed-in-line.
http://pcbunn.cithep.caltech.edu/jjb/Hallicrafters/S107/IMG_3069.jpg
+plus+ A Ground Screw with a Shorting/Jumper
Link/Wire between A2-to-G
You could use a simple pair of TV type Rabbit Ears
as a basic Indoor Shortwave Antenna connected to
the Two (2) Antenna Screw Terminals.
http://www.sdpb.org/reception/images/image006.png
Extend the Rabbit Ears as far as you can.
-or- You could use a simple FM Folded Dipole Antenna
as a basic Indoor Shortwave Antenna connected to
the Two (2) Antenna Screw Terminals.
http://www.parts-express.com/images/item_large/210-020_L.jpg
http://www.farnsworthelectronics.com/part%20images/antenn14.gif
http://www.siber-sonic.com/FM_reception/etc/dipolbld.gif
Stretch-out the Dipole Arms Horizontally to the max.
Note : Remove the Shorting/Jumper Link/Wire
between A2-to-G when using a Rabbit Ears a/o
Dipole Antenna with a Twin-Lead feed-in-line.
hope this helps - iane ~ RHF
.
.
dave
The OP implied otherwise.
arthr...@webtv.net
Got you this time...