On 12/1/2013 2:42 PM, amdx wrote:
On 12/1/2013 11:48 AM, Irv Finkleman wrote:
Before too much theorizing takes place, why not try just placing it in a
convenient location in the house -- you might be pleasantly surprised.
If that doesn't work, then, and only then, it becomes a technical
problem.

Irv VE6BP


That's good advice, except I have three different audio inputs that all
land where I now have the transmitter.
Besides, we like technical problems! :-)

After my last response to Jeff when I measured the output voltage, I
just realized I can check the loss through the LPF. Hot dog! Can't
wait to get home.
Mikek

Don't fool yourself. A 10x probe has maybe 10pF capacitance. What is
that reactance at 100MHz? About maybe 160 ohms? How will that affect
your measurement?

As far as an upside down vertical is concerned, you should get the free
copy of EZNEC and study what it is that you want to achieve. The ground
characteristics and the height above it is what determines the so-called
angle of max radiation. Height alone is sufficient to lower the angle.
For example, a perfectly conducting earth has an angle of maximum
radiation of zero degrees. Think about it.

"amdx" wrote in message
...
The receive area is small, 120" x 115", the antenna will be mounted 13"
in from the long dimension and 16" in from the smaller dimension,
basically in the corner of the lot, mounted 16 ft high.

Jeff, at this point, I have convinced myself putting a gain antenna on
the roof will solve any problem I may have. If not I can still remove 6db
of attenuation. So unless you want some mental exercise, don't over do it!

I am sure you mean feet ' instead of inches ". Without doing the math, I
would think that 150 feet would be the most you would need out of the
system. What is wrong with a horizontal dipole ? It should cover the area
just fine, and if not take out those attuenuators. I am not up on all the
part 15 rules, but I was thinking 100 milliwatts was fine to run. If you
can't hear it 200 feet away, I doubt the FCC is going to worry about it with
all the other things they have going on.

Could that buzzing noise you hear be some other signal such as cable leakage
or the AC power lines line noise ?

On 12/1/2013 5:17 PM, John S wrote:
On 12/1/2013 2:42 PM, amdx wrote:
On 12/1/2013 11:48 AM, Irv Finkleman wrote:
Before too much theorizing takes place, why not try just placing it in a
convenient location in the house -- you might be pleasantly surprised.
If that doesn't work, then, and only then, it becomes a technical
problem.

Irv VE6BP


That's good advice, except I have three different audio inputs that all
land where I now have the transmitter.
Besides, we like technical problems! :-)

After my last response to Jeff when I measured the output voltage, I
just realized I can check the loss through the LPF. Hot dog! Can't
wait to get home.
Mikek

Don't fool yourself. A 10x probe has maybe 10pF capacitance. What is
that reactance at 100MHz? About maybe 160 ohms? How will that affect
your measurement?


I don't know.

I put a T on the scope with 50 ohms on one side and the transmitter
driving the other side. The scope is 15pf/1Meg input impedance.


Two of the measurements I made a
50 ohms or antenna and with 110Mhz LPF and without LPF.
Transmitter at 87.5Mhz


50 ohm 7.33Vpp
l
Transmitter---LPF---l
l
scope


50 ohm 7.13Vpp
l
Transmitter---------l
l
scope

I don't know how the 15pf affects this measurement.
But I don't see much loss in my LPF.

Rubber Ducky 8.45Vpp
l
Transmitter---LPF---l
l
scope


Rubber Ducky 8.45Vpp
l
Transmitter---------l
l
scope

I checked this twice, I have digital voltage display on the scope.
So no loss at transmit frequency. I don't know how that works, I'll be
checking for radiation soon!

Is there anyway to compensate for the 15pf, could I put an equivalent
inductance in the scope input circuit? (for this frequency only)

I have two 3db attenuators, when I put those between the transmitter
and the LPF and the LPF and the Load (antenna/50 ohms) I get slightly
less loss with the 50 ohm load and slightly more loss with the antenna.


What say you?
Thanks, Mikek

PS.
I want to check the attenuation of the LPF at 175 Mhz and 262.5. I just
threw away a QST that had an article with a 220Mhz osc. I'll retrieve
that tomorrow.

On 12/1/2013 6:21 PM, Ralph Mowery wrote:

"amdx" wrote in message
...
The receive area is small, 120" x 115", the antenna will be mounted 13"
in from the long dimension and 16" in from the smaller dimension,
basically in the corner of the lot, mounted 16 ft high.

Jeff, at this point, I have convinced myself putting a gain antenna on
the roof will solve any problem I may have. If not I can still remove 6db
of attenuation. So unless you want some mental exercise, don't over do it!

I am sure you mean feet ' instead of inches ". Without doing the math, I
would think that 150 feet would be the most you would need out of the
system. What is wrong with a horizontal dipole ? It should cover the area
just fine, and if not take out those attuenuators. I am not up on all the
part 15 rules, but I was thinking 100 milliwatts was fine to run. If you
can't hear it 200 feet away, I doubt the FCC is going to worry about it with
all the other things they have going on.

I don't think so either, I just want to do the job with minimum power.
Now that I've messed with the new 110 Mhz filter a bit, I might remove
one 3 db attenuator and see how it works around the yard.

Could that buzzing noise you hear be some other signal such as cable leakage
or the AC power lines line noise ?


I think it's 60 hertz or a harmonic, but with enough RF, I don't think
I'd hear it.
It seemed better, after I added my LPF, I don't think because of the
filtering but maybe impedance changes.

Mikek

On 12/1/2013 7:17 PM, amdx wrote:
On 12/1/2013 5:17 PM, John S wrote:
On 12/1/2013 2:42 PM, amdx wrote:
On 12/1/2013 11:48 AM, Irv Finkleman wrote:
Before too much theorizing takes place, why not try just placing it
in a
convenient location in the house -- you might be pleasantly surprised.
If that doesn't work, then, and only then, it becomes a technical
problem.

Irv VE6BP


That's good advice, except I have three different audio inputs that all
land where I now have the transmitter.
Besides, we like technical problems! :-)

After my last response to Jeff when I measured the output voltage, I
just realized I can check the loss through the LPF. Hot dog! Can't
wait to get home.
Mikek

Don't fool yourself. A 10x probe has maybe 10pF capacitance. What is
that reactance at 100MHz? About maybe 160 ohms? How will that affect
your measurement?


I don't know.

If you can't calculate or reason out the answer, then you need a teacher
better than I.

On Sun, 1 Dec 2013 19:21:19 -0500, "Ralph Mowery"
wrote:

Could that buzzing noise you hear be some other signal such as cable leakage
or the AC power lines line noise ?

Trivia: Cable leakage has changed over the last few years. The sync
buzz of the analog TV era has been replaced by digital hiss. Put a
temporary antenna on your cable connection and listen on a suitable
receiver. Some cable systems still carry FM broadcast stations, so he
might also be hearing those coming from a cable leak. Locally,
everything was moved to digital channels in 2005.
http://www.sfgate.com/business/article/Comcast-to-restore-30-FM-radio-stations-Some-2625920.php

"Any sufficiently advanced communications technology is
indistiguishable from noise" (appologies to Arthur C. Clarke).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
Trivia: Cable leakage has changed over the last few years. The sync
buzz of the analog TV era has been replaced by digital hiss. Put a
temporary antenna on your cable connection and listen on a suitable
receiver. Some cable systems still carry FM broadcast stations, so he
might also be hearing those coming from a cable leak. Locally,
everything was moved to digital channels in 2005.
http://www.sfgate.com/business/article/Comcast-to-restore-30-FM-radio-stations-Some-2625920.php


I guess it depends on where you are Jeff. Around where I live there about
100 channels that are still analog. Still starting at the old channel 2.

The state I live in is still way behind times.

On Mon, 2 Dec 2013 00:00:37 -0500, "Ralph Mowery"
wrote:

"Jeff Liebermann" wrote in message
Trivia: Cable leakage has changed over the last few years. The sync
buzz of the analog TV era has been replaced by digital hiss. Put a
temporary antenna on your cable connection and listen on a suitable
receiver. Some cable systems still carry FM broadcast stations, so he
might also be hearing those coming from a cable leak. Locally,
everything was moved to digital channels in 2005.
http://www.sfgate.com/business/article/Comcast-to-restore-30-FM-radio-stations-Some-2625920.php

I guess it depends on where you are Jeff. Around where I live there about
100 channels that are still analog. Still starting at the old channel 2.

Comcast is now all digital in the People's Republic of Santa Cruz CA.
Of course Comcast has a new scam. You get up to two "free" DTA boxes:
http://customer.comcast.com/Pages/FAQViewer.aspx?seoid=What-is-a-digital-adapter
for listening to FM and viewing non-HD channels. It was originally
announced that it was "free" for 2 years, but Comcast started adding
$5/month per box to some peoples bills in about June.

One problem is that the DTA box somehow manages to produce worse than
analog quality TV pictures. Digital in, garbage out. I don't know
how they managed it, but the "free" box produces some of the worst
looking pictures I have ever seen since the introduction of color TV.
The Comcast solution is to rent a similar box, that produces HD video,
and amazingly produces decent looking non-HD video for $10/month.
That's $120/year per TV set for what used to be free:
http://bgr.com/2013/10/16/comcast-digital-adapter-criticism/
https://www.google.com/search?q=comcast+dta&tbm=isch
Oddly, both types of DTA boxes use the same digital data for non-HD
stations, so it's not Comcast that's sending garbage video. It's the
DTA box.

Both types of boxes will play some local FM stations, but I've only
tried it on the HD version. Works fine but will vary by area. For
Santa Cruz, we get about 30 stations.

The state I live in is still way behind times.

That may not be such a bad thing.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
Comcast is now all digital in the People's Republic of Santa Cruz CA.
Of course Comcast has a new scam. You get up to two "free" DTA boxes:
http://customer.comcast.com/Pages/FAQViewer.aspx?seoid=What-is-a-digital-adapter
for listening to FM and viewing non-HD channels. It was originally
announced that it was "free" for 2 years, but Comcast started adding
$5/month per box to some peoples bills in about June.

One problem is that the DTA box somehow manages to produce worse than
analog quality TV pictures. Digital in, garbage out. I don't know
how they managed it, but the "free" box produces some of the worst
looking pictures I have ever seen since the introduction of color TV.
The Comcast solution is to rent a similar box, that produces HD video,
and amazingly produces decent looking non-HD video for $10/month.
That's $120/year per TV set for what used to be free:
http://bgr.com/2013/10/16/comcast-digital-adapter-criticism/
https://www.google.com/search?q=comcast+dta&tbm=isch
Oddly, both types of DTA boxes use the same digital data for non-HD
stations, so it's not Comcast that's sending garbage video. It's the
DTA box.


I have an old cable ready TV that gets close to 100 of the analog chanels.
Just to see if it would work, I hooked up one of the off the air digital
converter boxes up to the cable an it did not pick up anything. Guess that
lets that out if our area goes to all digital.

A newer TV gets the analog and digital chanels off the cable. Then I have
one of the boxes hooked to the main TV.. If my wife could operate things, I
would go to something like Netflix.

The box does work off the air and I get about 30 chanels off the air with an
antenna out side the house.

Hi OM Mikek,

In practice, at such close range, it matters little how you mount your antenna. As such a rubber ducky would be good enough.

73,

Nandu
http://nandustips.blogspot.com