Re: Topband: Dayton Hamvention canceled

[Tim Duffy]

There is no Topband dinner for Dayton this year. Press release was sent out
last night.

See you in 2021

73
Tim K3LR
Dayton Top Band dinner chair

-Original Message-
From: Topband [mailto:topband-bounces+k3lr=k3lr@contesting.com] On
Behalf Of d...@np2j.com
Sent: Monday, March 16, 2020 5:53 PM
To: topband@contesting.com
Subject: Topband: Dayton Hamvention canceled

Dayton canceled
Guess No Topband Dinner this year folks
73
Dan K8RF/NP2J

Missed Spring Stew due to the Flu
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Was it a plane, was it a bird, was it Luis (IV3PRK) on 160 meters CW this morning?

[VE6WZ_Steve]

Yes it was!!
I was also very surprised when Luis IV3PRK answered my CQ last night. During 
the last min (2008-11) Luis was pretty much QRV every night.  My last QSO with 
him was Jan 2019.

Condx were quite good last night into EU, but not many callers….perhaps most 
were recovering from a weekend of contesting.

I worked IV3YYK, IK7TJF and IV3PRK….perhaps the Italian ops are staying home 
for CV-19 isolation.
Also logged, SM5EDX, SM5AOG, OM2XW, ON7PQ, PE5T and ON7DR.

The 160m DX season is not over yet.  The last EU DX in my log last spring was 
May 16, with many logged during the month of April.  The QRN levels are 
starting to get bad but fortunately from VE6 most of the US mid-west T-storm 
activity is off the side of the RX.

Lets keep the band going into spring.

73, de steve ve6wz



> On Mar 16, 2020, at 4:20 PM, Don Kirk  wrote:
> 
> Wow, just about fell out of my chair with Joy when I heard Luis (IV3PRK)
> calling North American stations on 160 meters CW this morning.
> 
> Luis had a very nice signal, and hope we continue to hear him on 160 meters
> CW like the old days.
> 
> Don (wd8dsb)
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Lee STRAHAN]

Hi Dave,
In my experience that is not a typical Norton amplifier gain . Most would be 
considerably in excess of that at 11  or 19 dB. They can run from 5 to 19 dB or 
so but what would be the purpose of only putting 5 dB there with an expensive 
amplifier configuration?  The ones I use are 11 dB gain. Just my $.02
Lee K7TJR

From: Dave Cuthbert 
Sent: Monday, March 16, 2020 3:05 PM
To: Lee STRAHAN 
Cc: topband@contesting.com
Subject: Re: Topband: Slightly OT - amplifier noise

Circuit gain is accounted for in my calculations. I ran a sim of the input amp 
and could get it to work with gains from 0.5 to 2 using different transformer 
ratios. So, I think the gain-of-2 I used is good enough.

On Mon, Mar 16, 2020 at 11:32 AM Lee STRAHAN 
mailto:k7...@msn.com>> wrote:
  Don’t forget there is gain in the signal paths. That first AUX input stage is 
a Norton configuration amp with gain controlled by the unknown transformer 
ratios. The two J-310's that sum the signals also appear to have a few dB gain. 
A full analysis of the circuit is necessary to derive what the insertion gain 
of this device would be. Or a measurement might be in order with gain pots at 
max. It could be amplified input device noise at the output.
Lee   K7TJR

-Original Message-
From: Topband 
mailto:msn@contesting.com>> 
On Behalf Of Dave Cuthbert
Sent: Monday, March 16, 2020 2:05 PM
To: n...@arrl.net
Cc: Topband mailto:topband@contesting.com>>; Guy 
Olinger K2AV mailto:k2av@gmail.com>>
Subject: Re: Topband: Slightly OT - amplifier noise

Steve,

I performed a hand calculation of the MFJ-1025 14 MHz noise and it's (only)
9 nV/Hz^0.5, or 0.2 uV in 500 Hz. This is -120 dBm, or S-1. But you measure
S-4 noise. What is going on?

Questions to determine what is going on:

Question 1) What model is the radio?
Question 2: What bandwidth is the noise measured with?
Question 3: What band?
Question 4: What does the radio  measure connected to the MFJ-1025 but with 
the MFJ powered OFF?


*MFJ-1025 termination *
With the two MFJ-1025 antenna terminals left open the two JFET inputs are 
terminated in 0-78 ohms depending on the gain pot settings. Note that gain pots 
reduce the signal but not JFET noise and cutting the gain degrades the S/N 
ratio. With the gain pots at maximum the unterminated input noise from the 
resistors is (only) 1.1 nV/Hz^0.5.

*MFJ-1025 noise calculations*
Let's add up all the noise sources and derive the 14 MHz noise.

*Q4 output buffer*
   Q5 voltage gain, 1
   1 nV/Hz^0.5 transistor (my estimate; I can calculate it but it's low enough 
to just call it 1 nV/Hz^0.5)
   1.9 nV/Hz^0.5 for R8 (220 ohms)
   Total input noise 2.2 nV/Hz^0.5 (the transistor noise is my estimate)
   Total output noise 2.2 nV/Hz^0.5

*Q5, Q6 active combiner*
   Q5 voltage gain, 1.1
   R9||R26, 1.1 nV/Hz^0.5
   Q5 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 1.4 nV/Hz^0.5

   Q6 voltage gain, 2.3
   R13, 1.9 nV/Hz^0.5
   Q6 gate, 0.6 nV/Hz^0.5
   Input noise, 2.0 nV/Hz^0.5
   Output noise, 4.6 nV/Hz^0.5

   Q5 + Q6 noise
   Output noise, 4.8 nV/Hz^0.5

   *Q7 phase splitter*
   Q7 voltage gain, 1
   Q7 gate, 0.6 nV/Hz^0.5
   R13, 1.9 nV/Hz^0.5
   Output noise, 2.0 nV/Hz

   *Q8 AUX amp *
   Q8 voltage gain, 2 (that's a guess)
   R20||R27, 1.1 nV/Hz^0.5
   Q8 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 2.6 nV/Hz^0.5

*Adding it up*
The noise into Q6 is the AUX amp (2.6 nV/Hz^0.5) + the phase splitter (2.0
nV/Hz) = 3.3 nV/Hz^0.5

The noise out of Q6 is X2.3 the input noise = 7.5 nV/Hz The noise out of Q5 is 
4.8 nV/Hz^0.5 Adding two these together the noise into Q4 is 8.9 nV/Hz Add 1 
nV/Hz^0.5  for Q1 and we have 9.0 nV/Hz

The MFJ-1025 *output noise is 9 nV/Hz^0.5*

In a 500 Hz BW this is 200 nV, or 48 dB below S-9. *This is S-1*.
The AUX-referred noise is ~1.7 nV/Hz^0.5 The MAIN-referred noise is ~8 nV/Hz^0.5

*12V Power is well decoupled*
The 12V power is well decoupled with 14 MHz PS rejection ratio of 110 dB.
This is calculated for bypass cap C7 having 10 nH lead inductance. So, I don't 
see that noise on the 12V source makes a difference.

*LTSpice J310 noise model issue*
I ran sims of a J310 JFET in a simple source-follower circuit and LTSpice 
reports noise that is so far off it's unusable. Instead I use a claimed noise 
figure of 3 dB. If I use the specified 100 Hz noise of 10 nV/Hz^0.5 the output 
noise rises enough to make S-4 noise. But, I believe the 100 Hz noise is below 
the J310 1/f frequency and is much higher than the HF noise.
I think I can calculate the 1/f frequency to make sure. About 10 years ago I 
designed a test setup to measure MOSFET noise and ran thru the calculations for 
1/f and noise.

*References*
MFJ-1025 manual with schematic:
https://www.mfjenterprises.com/support.php?productid=MFJ-1025

J310 datasheet:
http://pdf.datasheetcatalog.com/datasheet_pdf/intersil/J308_to_J310.pdf

J310 RF amp noise figure: 

Topband: Was it a plane, was it a bird, was it Luis (IV3PRK) on 160 meters CW this morning?

[Don Kirk]

Wow, just about fell out of my chair with Joy when I heard Luis (IV3PRK)
calling North American stations on 160 meters CW this morning.

Luis had a very nice signal, and hope we continue to hear him on 160 meters
CW like the old days.

Don (wd8dsb)
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Dave Cuthbert]

Circuit gain is accounted for in my calculations. I ran a sim of the input
amp and could get it to work with gains from 0.5 to 2 using different
transformer ratios. So, I think the gain-of-2 I used is good enough.

On Mon, Mar 16, 2020 at 11:32 AM Lee STRAHAN  wrote:

>   Don’t forget there is gain in the signal paths. That first AUX input
> stage is a Norton configuration amp with gain controlled by the unknown
> transformer ratios. The two J-310's that sum the signals also appear to
> have a few dB gain. A full analysis of the circuit is necessary to derive
> what the insertion gain of this device would be. Or a measurement might be
> in order with gain pots at max. It could be amplified input device noise at
> the output.
> Lee   K7TJR
>
> -Original Message-
> From: Topband  On Behalf Of
> Dave Cuthbert
> Sent: Monday, March 16, 2020 2:05 PM
> To: n...@arrl.net
> Cc: Topband ; Guy Olinger K2AV  >
> Subject: Re: Topband: Slightly OT - amplifier noise
>
> Steve,
>
> I performed a hand calculation of the MFJ-1025 14 MHz noise and it's (only)
> 9 nV/Hz^0.5, or 0.2 uV in 500 Hz. This is -120 dBm, or S-1. But you measure
> S-4 noise. What is going on?
>
> Questions to determine what is going on:
>
> Question 1) What model is the radio?
> Question 2: What bandwidth is the noise measured with?
> Question 3: What band?
> Question 4: What does the radio  measure connected to the MFJ-1025 but
> with the MFJ powered OFF?
>
>
> *MFJ-1025 termination *
> With the two MFJ-1025 antenna terminals left open the two JFET inputs are
> terminated in 0-78 ohms depending on the gain pot settings. Note that gain
> pots reduce the signal but not JFET noise and cutting the gain degrades the
> S/N ratio. With the gain pots at maximum the unterminated input noise from
> the resistors is (only) 1.1 nV/Hz^0.5.
>
> *MFJ-1025 noise calculations*
> Let's add up all the noise sources and derive the 14 MHz noise.
>
> *Q4 output buffer*
>Q5 voltage gain, 1
>1 nV/Hz^0.5 transistor (my estimate; I can calculate it but it's low
> enough to just call it 1 nV/Hz^0.5)
>1.9 nV/Hz^0.5 for R8 (220 ohms)
>Total input noise 2.2 nV/Hz^0.5 (the transistor noise is my estimate)
>Total output noise 2.2 nV/Hz^0.5
>
> *Q5, Q6 active combiner*
>Q5 voltage gain, 1.1
>R9||R26, 1.1 nV/Hz^0.5
>Q5 gate, 0.6 nV/Hz^0.5
>Input noise, 1.3 nV/Hz^0.5
>Output noise, 1.4 nV/Hz^0.5
>
>Q6 voltage gain, 2.3
>R13, 1.9 nV/Hz^0.5
>Q6 gate, 0.6 nV/Hz^0.5
>Input noise, 2.0 nV/Hz^0.5
>Output noise, 4.6 nV/Hz^0.5
>
>Q5 + Q6 noise
>Output noise, 4.8 nV/Hz^0.5
>
>*Q7 phase splitter*
>Q7 voltage gain, 1
>Q7 gate, 0.6 nV/Hz^0.5
>R13, 1.9 nV/Hz^0.5
>Output noise, 2.0 nV/Hz
>
>*Q8 AUX amp *
>Q8 voltage gain, 2 (that's a guess)
>R20||R27, 1.1 nV/Hz^0.5
>Q8 gate, 0.6 nV/Hz^0.5
>Input noise, 1.3 nV/Hz^0.5
>Output noise, 2.6 nV/Hz^0.5
>
> *Adding it up*
> The noise into Q6 is the AUX amp (2.6 nV/Hz^0.5) + the phase splitter (2.0
> nV/Hz) = 3.3 nV/Hz^0.5
>
> The noise out of Q6 is X2.3 the input noise = 7.5 nV/Hz The noise out of
> Q5 is 4.8 nV/Hz^0.5 Adding two these together the noise into Q4 is 8.9
> nV/Hz Add 1 nV/Hz^0.5  for Q1 and we have 9.0 nV/Hz
>
> The MFJ-1025 *output noise is 9 nV/Hz^0.5*
>
> In a 500 Hz BW this is 200 nV, or 48 dB below S-9. *This is S-1*.
> The AUX-referred noise is ~1.7 nV/Hz^0.5 The MAIN-referred noise is ~8
> nV/Hz^0.5
>
> *12V Power is well decoupled*
> The 12V power is well decoupled with 14 MHz PS rejection ratio of 110 dB.
> This is calculated for bypass cap C7 having 10 nH lead inductance. So, I
> don't see that noise on the 12V source makes a difference.
>
> *LTSpice J310 noise model issue*
> I ran sims of a J310 JFET in a simple source-follower circuit and LTSpice
> reports noise that is so far off it's unusable. Instead I use a claimed
> noise figure of 3 dB. If I use the specified 100 Hz noise of 10 nV/Hz^0.5
> the output noise rises enough to make S-4 noise. But, I believe the 100 Hz
> noise is below the J310 1/f frequency and is much higher than the HF noise.
> I think I can calculate the 1/f frequency to make sure. About 10 years ago
> I designed a test setup to measure MOSFET noise and ran thru the
> calculations for 1/f and noise.
>
> *References*
> MFJ-1025 manual with schematic:
> https://www.mfjenterprises.com/support.php?productid=MFJ-1025
>
> J310 datasheet:
> http://pdf.datasheetcatalog.com/datasheet_pdf/intersil/J308_to_J310.pdf
>
> J310 RF amp noise figure: http://receiverforjupiter.tripod.com/rfamp.htm
>
> Dave KH6AQ
>
>
> On Mon, Mar 16, 2020 at 8:33 AM Steve London  wrote:
>
> > I did that - terminated in 50 ohms.
> >
> > 73,
> > Steve, N2IC
> >
> > On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
> > > Depending on the exact circuit and device, to measure noise from the
> > device
> > > itself, don’t you have to terminate the inputs to put the normal
> > impedance on
> > > them? 

Topband: Dayton Hamvention canceled

[dan]

Dayton canceled
Guess No Topband Dinner this year folks
73
Dan K8RF/NP2J

Missed Spring Stew due to the Flu
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Lee STRAHAN]

  Don’t forget there is gain in the signal paths. That first AUX input stage is 
a Norton configuration amp with gain controlled by the unknown transformer 
ratios. The two J-310's that sum the signals also appear to have a few dB gain. 
A full analysis of the circuit is necessary to derive what the insertion gain 
of this device would be. Or a measurement might be in order with gain pots at 
max. It could be amplified input device noise at the output.
Lee   K7TJR

-Original Message-
From: Topband  On Behalf Of Dave 
Cuthbert
Sent: Monday, March 16, 2020 2:05 PM
To: n...@arrl.net
Cc: Topband ; Guy Olinger K2AV 
Subject: Re: Topband: Slightly OT - amplifier noise

Steve,

I performed a hand calculation of the MFJ-1025 14 MHz noise and it's (only)
9 nV/Hz^0.5, or 0.2 uV in 500 Hz. This is -120 dBm, or S-1. But you measure
S-4 noise. What is going on?

Questions to determine what is going on:

Question 1) What model is the radio?
Question 2: What bandwidth is the noise measured with?
Question 3: What band?
Question 4: What does the radio  measure connected to the MFJ-1025 but with 
the MFJ powered OFF?


*MFJ-1025 termination *
With the two MFJ-1025 antenna terminals left open the two JFET inputs are 
terminated in 0-78 ohms depending on the gain pot settings. Note that gain pots 
reduce the signal but not JFET noise and cutting the gain degrades the S/N 
ratio. With the gain pots at maximum the unterminated input noise from the 
resistors is (only) 1.1 nV/Hz^0.5.

*MFJ-1025 noise calculations*
Let's add up all the noise sources and derive the 14 MHz noise.

*Q4 output buffer*
   Q5 voltage gain, 1
   1 nV/Hz^0.5 transistor (my estimate; I can calculate it but it's low enough 
to just call it 1 nV/Hz^0.5)
   1.9 nV/Hz^0.5 for R8 (220 ohms)
   Total input noise 2.2 nV/Hz^0.5 (the transistor noise is my estimate)
   Total output noise 2.2 nV/Hz^0.5

*Q5, Q6 active combiner*
   Q5 voltage gain, 1.1
   R9||R26, 1.1 nV/Hz^0.5
   Q5 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 1.4 nV/Hz^0.5

   Q6 voltage gain, 2.3
   R13, 1.9 nV/Hz^0.5
   Q6 gate, 0.6 nV/Hz^0.5
   Input noise, 2.0 nV/Hz^0.5
   Output noise, 4.6 nV/Hz^0.5

   Q5 + Q6 noise
   Output noise, 4.8 nV/Hz^0.5

   *Q7 phase splitter*
   Q7 voltage gain, 1
   Q7 gate, 0.6 nV/Hz^0.5
   R13, 1.9 nV/Hz^0.5
   Output noise, 2.0 nV/Hz

   *Q8 AUX amp *
   Q8 voltage gain, 2 (that's a guess)
   R20||R27, 1.1 nV/Hz^0.5
   Q8 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 2.6 nV/Hz^0.5

*Adding it up*
The noise into Q6 is the AUX amp (2.6 nV/Hz^0.5) + the phase splitter (2.0
nV/Hz) = 3.3 nV/Hz^0.5

The noise out of Q6 is X2.3 the input noise = 7.5 nV/Hz The noise out of Q5 is 
4.8 nV/Hz^0.5 Adding two these together the noise into Q4 is 8.9 nV/Hz Add 1 
nV/Hz^0.5  for Q1 and we have 9.0 nV/Hz

The MFJ-1025 *output noise is 9 nV/Hz^0.5*

In a 500 Hz BW this is 200 nV, or 48 dB below S-9. *This is S-1*.
The AUX-referred noise is ~1.7 nV/Hz^0.5 The MAIN-referred noise is ~8 nV/Hz^0.5

*12V Power is well decoupled*
The 12V power is well decoupled with 14 MHz PS rejection ratio of 110 dB.
This is calculated for bypass cap C7 having 10 nH lead inductance. So, I don't 
see that noise on the 12V source makes a difference.

*LTSpice J310 noise model issue*
I ran sims of a J310 JFET in a simple source-follower circuit and LTSpice 
reports noise that is so far off it's unusable. Instead I use a claimed noise 
figure of 3 dB. If I use the specified 100 Hz noise of 10 nV/Hz^0.5 the output 
noise rises enough to make S-4 noise. But, I believe the 100 Hz noise is below 
the J310 1/f frequency and is much higher than the HF noise.
I think I can calculate the 1/f frequency to make sure. About 10 years ago I 
designed a test setup to measure MOSFET noise and ran thru the calculations for 
1/f and noise.

*References*
MFJ-1025 manual with schematic:
https://www.mfjenterprises.com/support.php?productid=MFJ-1025

J310 datasheet:
http://pdf.datasheetcatalog.com/datasheet_pdf/intersil/J308_to_J310.pdf

J310 RF amp noise figure: http://receiverforjupiter.tripod.com/rfamp.htm

Dave KH6AQ


On Mon, Mar 16, 2020 at 8:33 AM Steve London  wrote:

> I did that - terminated in 50 ohms.
>
> 73,
> Steve, N2IC
>
> On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
> > Depending on the exact circuit and device, to measure noise from the
> device
> > itself, don’t you have to terminate the inputs to put the normal
> impedance on
> > them? The circuits are often designed with the coax Z zero in mind.
> >
> > 73, Guy K2AV
> >
> > On Mon, Mar 16, 2020 at 12:47 PM Steve London  > > wrote:
> >
> > This has been a very interesting thread - Thanks for all the input.
> >
> > Perhaps I have set my expectations too high.
> >
> > A typical application is on 15 meters, late in the opening, 
> > working
> JA's from
> > here in SW New Mexico. Absent any local QRN, the band is very quiet.
> 

Re: Topband: Slightly OT - amplifier noise

[Dave Cuthbert]

Steve,

I performed a hand calculation of the MFJ-1025 14 MHz noise and it's (only)
9 nV/Hz^0.5, or 0.2 uV in 500 Hz. This is -120 dBm, or S-1. But you measure
S-4 noise. What is going on?

Questions to determine what is going on:

Question 1) What model is the radio?
Question 2: What bandwidth is the noise measured with?
Question 3: What band?
Question 4: What does the radio  measure connected to the MFJ-1025 but
with the MFJ powered OFF?


*MFJ-1025 termination *
With the two MFJ-1025 antenna terminals left open the two JFET inputs are
terminated in 0-78 ohms depending on the gain pot settings. Note that gain
pots reduce the signal but not JFET noise and cutting the gain degrades the
S/N ratio. With the gain pots at maximum the unterminated input noise from
the resistors is (only) 1.1 nV/Hz^0.5.

*MFJ-1025 noise calculations*
Let's add up all the noise sources and derive the 14 MHz noise.

*Q4 output buffer*
   Q5 voltage gain, 1
   1 nV/Hz^0.5 transistor (my estimate; I can calculate it but it's low
enough to just call it 1 nV/Hz^0.5)
   1.9 nV/Hz^0.5 for R8 (220 ohms)
   Total input noise 2.2 nV/Hz^0.5 (the transistor noise is my estimate)
   Total output noise 2.2 nV/Hz^0.5

*Q5, Q6 active combiner*
   Q5 voltage gain, 1.1
   R9||R26, 1.1 nV/Hz^0.5
   Q5 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 1.4 nV/Hz^0.5

   Q6 voltage gain, 2.3
   R13, 1.9 nV/Hz^0.5
   Q6 gate, 0.6 nV/Hz^0.5
   Input noise, 2.0 nV/Hz^0.5
   Output noise, 4.6 nV/Hz^0.5

   Q5 + Q6 noise
   Output noise, 4.8 nV/Hz^0.5

   *Q7 phase splitter*
   Q7 voltage gain, 1
   Q7 gate, 0.6 nV/Hz^0.5
   R13, 1.9 nV/Hz^0.5
   Output noise, 2.0 nV/Hz

   *Q8 AUX amp *
   Q8 voltage gain, 2 (that's a guess)
   R20||R27, 1.1 nV/Hz^0.5
   Q8 gate, 0.6 nV/Hz^0.5
   Input noise, 1.3 nV/Hz^0.5
   Output noise, 2.6 nV/Hz^0.5

*Adding it up*
The noise into Q6 is the AUX amp (2.6 nV/Hz^0.5) + the phase splitter (2.0
nV/Hz) = 3.3 nV/Hz^0.5

The noise out of Q6 is X2.3 the input noise = 7.5 nV/Hz
The noise out of Q5 is 4.8 nV/Hz^0.5
Adding two these together the noise into Q4 is 8.9 nV/Hz
Add 1 nV/Hz^0.5  for Q1 and we have 9.0 nV/Hz

The MFJ-1025 *output noise is 9 nV/Hz^0.5*

In a 500 Hz BW this is 200 nV, or 48 dB below S-9. *This is S-1*.
The AUX-referred noise is ~1.7 nV/Hz^0.5
The MAIN-referred noise is ~8 nV/Hz^0.5

*12V Power is well decoupled*
The 12V power is well decoupled with 14 MHz PS rejection ratio of 110 dB.
This is calculated for bypass cap C7 having 10 nH lead inductance. So, I
don't see that noise on the 12V source makes a difference.

*LTSpice J310 noise model issue*
I ran sims of a J310 JFET in a simple source-follower circuit and LTSpice
reports noise that is so far off it's unusable. Instead I use a claimed
noise figure of 3 dB. If I use the specified 100 Hz noise of 10 nV/Hz^0.5
the output noise rises enough to make S-4 noise. But, I believe the 100 Hz
noise is below the J310 1/f frequency and is much higher than the HF noise.
I think I can calculate the 1/f frequency to make sure. About 10 years ago
I designed a test setup to measure MOSFET noise and ran thru the
calculations for 1/f and noise.

*References*
MFJ-1025 manual with schematic:
https://www.mfjenterprises.com/support.php?productid=MFJ-1025

J310 datasheet:
http://pdf.datasheetcatalog.com/datasheet_pdf/intersil/J308_to_J310.pdf

J310 RF amp noise figure: http://receiverforjupiter.tripod.com/rfamp.htm

Dave KH6AQ


On Mon, Mar 16, 2020 at 8:33 AM Steve London  wrote:

> I did that - terminated in 50 ohms.
>
> 73,
> Steve, N2IC
>
> On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
> > Depending on the exact circuit and device, to measure noise from the
> device
> > itself, don’t you have to terminate the inputs to put the normal
> impedance on
> > them? The circuits are often designed with the coax Z zero in mind.
> >
> > 73, Guy K2AV
> >
> > On Mon, Mar 16, 2020 at 12:47 PM Steve London  > > wrote:
> >
> > This has been a very interesting thread - Thanks for all the input.
> >
> > Perhaps I have set my expectations too high.
> >
> > A typical application is on 15 meters, late in the opening, working
> JA's from
> > here in SW New Mexico. Absent any local QRN, the band is very quiet.
> Any local
> > noise covers the bottom layer of 5 watt JA's calling me.
> >
> > I did some more testing with the MFJ-1025. With no antennas
> connected, the box
> > raises the noise floor about 10 dB, irrespective of the Aux Antenna
> Gain or the
> > Main Antenna Gain. I haven't yet tried powering from a battery, to
> make sure
> > the
> > power supply isn't the source. Assuming the J310's are quiet, that
> leaves the
> > 2N5109 emitter follower, or the back-to-back protection diodes.
> Might also try
> > disconnecting the RF sense circuit.
> >
> > 73,
> > Steve, N2IC
> > _
> > Searchable Archives: 

Re: Topband: Slightly OT - amplifier noise

[Mike Waters]

This is what I have been thinking all along.

On Mon, Mar 16, 2020, 1:47 PM Lloyd - N9LB  wrote:

> Possibly static, nearby lightning, or high levels of TX RF may have
> damaged one or more of the semiconductors in your MFJ-1025.
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Lloyd - N9LB]

Possibly static, nearby lightning, or high levels of TX RF may have damaged one 
or more of the semiconductors in your MFJ-1025.

-Original Message-
From: Topband [mailto:topband-bounces+lloydberg=tds@contesting.com] On 
Behalf Of Steve London
Sent: Monday, March 16, 2020 1:33 PM
To: Guy Olinger K2AV 
Cc: Topband 
Subject: Re: Topband: Slightly OT - amplifier noise

I did that - terminated in 50 ohms.

73,
Steve, N2IC

On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
> Depending on the exact circuit and device, to measure noise from the 
> device itself, don’t you have to terminate the inputs to put the 
> normal impedance on them? The circuits are often designed with the coax Z 
> zero in mind.
> 
> 73, Guy K2AV
> 
> On Mon, Mar 16, 2020 at 12:47 PM Steve London  > wrote:
> 
> This has been a very interesting thread - Thanks for all the input.
> 
> Perhaps I have set my expectations too high.
> 
> A typical application is on 15 meters, late in the opening, working JA's 
> from
> here in SW New Mexico. Absent any local QRN, the band is very quiet. Any 
> local
> noise covers the bottom layer of 5 watt JA's calling me.
> 
> I did some more testing with the MFJ-1025. With no antennas connected, 
> the box
> raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain 
> or the
> Main Antenna Gain. I haven't yet tried powering from a battery, to make 
> sure
> the
> power supply isn't the source. Assuming the J310's are quiet, that leaves 
> the
> 2N5109 emitter follower, or the back-to-back protection diodes. Might 
> also try
> disconnecting the RF sense circuit.
> 
> 73,
> Steve, N2IC
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband 
> Reflector
> 
> --
> Sent via Gmail Mobile on my iPhone
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: NVIS Antenna

[Jim Brown]

Roger,

I think you're observations propagation are correct, but I strongly 
disagree with the paragraph below. My experience has been that IF the 
antenna is accurately modeled, ground characteristics accurately 
represent where the antenna is rigged, and the appropriate NEC ground 
model is selected, modelling WILL correctly predict it's performance 
over FLAT terrain. It's well known that non-flat terrain has major 
effects on horizontally polarized waves, and N6BT has recently published 
his work showing that it also strongly affects vertically polarized waves.


73, Jim K9YC

On 3/16/2020 5:52 AM, Roger Kennedy wrote:

The only other factor I DO think is that if you have a low dipole on 160m
but DON'T have any radials or anything underneath it, it probably radiates
more low angle than computer-modelling software would suggest. I believe the
errors occur on 160m because it can't properly forecast the effect of the
REAL WORLD ground when the antenna is a fraction of a wavelength above it.


_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Stew Perry Contest

[uy0zg]

Hi

I heard you Roger.

But did not distract you from your beloved CQ dx TEST :-))

Almost all of my NA correspondents are old acquaintances.

There are only two new ones - N4BAA, AA2EQ.

There was one QSO with the third zone - K7RL ( It has wonderful TX + 
RX).


Also, many from the USA heard me well.

Only a few stations did not answer me.

Five times I tried to call NN7CW.
Lost about 30 minutes .
And now everything is clear..

http://lists.contesting.com/_3830/2020-03/msg03876.html

But overall a great contest !



---
Nick, UY0ZG
http://www.topband.in.ua

Roger Kennedy писал 2020-03-16 14:55:
Yes, great to see conditions being good this weekend for the Contest.  
The
big NA signals were peaking S9 +10 to 15dB over here (which what they 
always

used to be, but I haven't seen for a while)

I came on for a couple of hours on Saturday night, and managed to work 
45 NA

stations, including several Caribbeans.

It's just a shame that you never hear most of these stations on 160 the 
rest

of the time !

Roger G3YRO

_
Searchable Archives: http://www.contesting.com/_topband - Topband 
Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Steve London]

I did that - terminated in 50 ohms.

73,
Steve, N2IC

On 03/16/2020 12:27 PM, Guy Olinger K2AV wrote:
Depending on the exact circuit and device, to measure noise from the device 
itself, don’t you have to terminate the inputs to put the normal impedance on 
them? The circuits are often designed with the coax Z zero in mind.


73, Guy K2AV

On Mon, Mar 16, 2020 at 12:47 PM Steve London > wrote:


This has been a very interesting thread - Thanks for all the input.

Perhaps I have set my expectations too high.

A typical application is on 15 meters, late in the opening, working JA's 
from
here in SW New Mexico. Absent any local QRN, the band is very quiet. Any 
local
noise covers the bottom layer of 5 watt JA's calling me.

I did some more testing with the MFJ-1025. With no antennas connected, the 
box
raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain or 
the
Main Antenna Gain. I haven't yet tried powering from a battery, to make sure
the
power supply isn't the source. Assuming the J310's are quiet, that leaves 
the
2N5109 emitter follower, or the back-to-back protection diodes. Might also 
try
disconnecting the RF sense circuit.

73,
Steve, N2IC
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

--
Sent via Gmail Mobile on my iPhone

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Guy Olinger K2AV]

Depending on the exact circuit and device, to measure noise from the device
itself, don’t you have to terminate the inputs to put the normal impedance
on them? The circuits are often designed with the coax Z zero in mind.

73, Guy K2AV

On Mon, Mar 16, 2020 at 12:47 PM Steve London  wrote:

> This has been a very interesting thread - Thanks for all the input.
>
> Perhaps I have set my expectations too high.
>
> A typical application is on 15 meters, late in the opening, working JA's
> from
> here in SW New Mexico. Absent any local QRN, the band is very quiet. Any
> local
> noise covers the bottom layer of 5 watt JA's calling me.
>
> I did some more testing with the MFJ-1025. With no antennas connected, the
> box
> raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain
> or the
> Main Antenna Gain. I haven't yet tried powering from a battery, to make
> sure the
> power supply isn't the source. Assuming the J310's are quiet, that leaves
> the
> 2N5109 emitter follower, or the back-to-back protection diodes. Might also
> try
> disconnecting the RF sense circuit.
>
> 73,
> Steve, N2IC
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
-- 
Sent via Gmail Mobile on my iPhone
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: NVIS Antenna

[Mike Waters]

I fully agree with the statements below. *Most* of the time, a vertical is
superior for DX on 160m. Please see:
https://web.archive.org/web/20170703105635/http://www.w0btu.com/160_meters.html

73, Mike
W0BTU

On Mon, Mar 16, 2020, 7:52 AM Roger Kennedy 
wrote:

>
> ... DX propagation on 160m ISN'T like 80m (where it IS nearly all low
> angle, so you MUST have a good vertical to work DX effectively) ... Most of
> the "experts" who have written books about Low-band DX-ing have made the
> assumption that 160m is just like 80m . . . which in my experience it
> clearly isn't ! ...
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Slightly OT - amplifier noise

[Steve London]

This has been a very interesting thread - Thanks for all the input.

Perhaps I have set my expectations too high.

A typical application is on 15 meters, late in the opening, working JA's from 
here in SW New Mexico. Absent any local QRN, the band is very quiet. Any local 
noise covers the bottom layer of 5 watt JA's calling me.


I did some more testing with the MFJ-1025. With no antennas connected, the box 
raises the noise floor about 10 dB, irrespective of the Aux Antenna Gain or the 
Main Antenna Gain. I haven't yet tried powering from a battery, to make sure the 
power supply isn't the source. Assuming the J310's are quiet, that leaves the 
2N5109 emitter follower, or the back-to-back protection diodes. Might also try 
disconnecting the RF sense circuit.


73,
Steve, N2IC
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: NVIS Antenna

[dj7ww]

There is nothing special, a 50 feet high dipole has at 25° elevation angle
the same gain as a shortened vertical over lossy ground or with just a few
radials.

73
Peter

-Original Message-
From: Topband [mailto:topband-bounces+dj7ww=t-online...@contesting.com] On
Behalf Of Roger Kennedy
Sent: Montag, 16. März 2020 13:52
To: topband@contesting.com
Subject: Topband: NVIS Antenna


Well I've said it dozens of times before . . . but I have used a horizontal
halfwave Dipole (at about 50ft)
for working DX on 160m for the past 50 years !  (and that's at 6 different
QTHs)

Not only do I work all over the world, but I know my signal often compares
pretty well with other Gs using good verticals . . . and I have no problem
getting through the pile-ups working the various DX-peditions.

How is this possible?   Well in my opinion it's because DX propagation on
160m ISN'T like 80m (where it IS nearly all low angle, so you MUST have a
good vertical to work DX effectively)

Based on the hundreds of comparison QSOs I've had over the decades, I figure
that on 160m, propagation MUST be fairly high angle a lot of the time,
presumably because of inter-layer reflections or ducting.

Most of the "experts" who have written books about Low-band DX-ing have made
the assumption that 160m is just like 80m . . . which in my experience it
clearly isn't !

The only other factor I DO think is that if you have a low dipole on 160m
but DON'T have any radials or anything underneath it, it probably radiates
more low angle than computer-modelling software would suggest. I believe the
errors occur on 160m because it can't properly forecast the effect of the
REAL WORLD ground when the antenna is a fraction of a wavelength above it.

Roger G3YRO
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Stew Perry Contest

[Roger Kennedy]

Yes, great to see conditions being good this weekend for the Contest.  The
big NA signals were peaking S9 +10 to 15dB over here (which what they always
used to be, but I haven't seen for a while)

I came on for a couple of hours on Saturday night, and managed to work 45 NA
stations, including several Caribbeans.

It's just a shame that you never hear most of these stations on 160 the rest
of the time !

Roger G3YRO

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: NVIS Antenna

[Roger Kennedy]

Well I've said it dozens of times before . . . but I have used a horizontal
halfwave Dipole (at about 50ft)
for working DX on 160m for the past 50 years !  (and that's at 6 different
QTHs)

Not only do I work all over the world, but I know my signal often compares
pretty well with other Gs using good verticals . . . and I have no problem
getting through the pile-ups working the various DX-peditions.

How is this possible?   Well in my opinion it's because DX propagation on
160m ISN'T like 80m (where it IS nearly all low angle, so you MUST have a
good vertical to work DX effectively)

Based on the hundreds of comparison QSOs I've had over the decades, I figure
that on 160m, propagation MUST be fairly high angle a lot of the time,
presumably because of inter-layer reflections or ducting.

Most of the "experts" who have written books about Low-band DX-ing have made
the assumption that 160m is just like 80m . . . which in my experience it
clearly isn't !

The only other factor I DO think is that if you have a low dipole on 160m
but DON'T have any radials or anything underneath it, it probably radiates
more low angle than computer-modelling software would suggest. I believe the
errors occur on 160m because it can't properly forecast the effect of the
REAL WORLD ground when the antenna is a fraction of a wavelength above it.

Roger G3YRO
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: NVIS Antenna

[Brian Campbell]

Back in 2017 I put up a 160M Inverted V with the apex at about 35' and the ends 
at 8' with the only goal being to try inband SO2R on 160M. My reasoning was the 
V "should" be able to work stations out to ~500Km ( 300 Miles ) and more 
importantly hold my run QRG while I went up the band to S for Mults with the 
second radio and my "real" antenna ( Inverted L with 105' vertical and with 
>20,000' of radials ).

To my amazement I was getting RBN hits from coast to coast in NA as well as the 
northern part of SA. The reports were on average about 10db - 15db lower than 
my TX vertical "but" I was still being heard. So in the 2018 and 2019 CQ160 CW 
and ARRL 160 contests I was SO2R and both years I was called by stations from 
as close as 100 km to as far as the West coast of NA ( ~3,500 km ), and as far 
south as the  Southern Caribbean ( also ~3,500 km ) on the low Inverted V. So 
not only did it hold my QRG but it worked a lot better than I had thought it 
would beforehand.

Then on 2018-03-27 at 11:10z ( SR -4 min ) I even worked VK3HJ ( thanks Luke ) 
16,116 km away with it as well so as Carl says "it's better than no antenna". 
Also that QSO was most likely ducting propagation as it only happened after I 
had lost all of Luke's signal on my vertical and then switched over to the V 
where he was Q5 and ~S3.

All the above was done with 100 watts so if you ( or I ) had run legal limit 
power the results would have been even better.

FYI I am no longer doing inband SO2R on 160 ( or any other band ) after having 
too many close calls with frying a front end. So caveat emptor if you try it.

73,
Brian
VE3MGY













From: Topband  on behalf of 
Carl Luetzelschwab 
Sent: March 15, 2020 3:47 PM
To: topBand List 
Subject: Re: Topband: NVIS Antenna

For those who are antenna challenged, don't sell a 160m inverted-vee at low
height too short.

My 160m antenna at the moment is an inverted-vee at an apex of 45 feet.
Additionally, the last third of each end is at 90 degrees to the main
portion and horizontal at only 7 feet or so off the ground. It's what fits
on the property.

In the CQ 160m CW contest in January 2017. I came away with 44 states
(missed ME, ID, NE and AK), 7 Canadian provinces (VE9, VY2, VE2, VE3, VE5,
VE6 and VE7) and 17 DXCC entities (mostly Caribbean, Central America,
Mexico and South America, with a few Europeans, a North African and a KH6
in the mix). I was seldom #1 in a pile-up, but eventually I usually got
through with 800 Watts to the inv-vee.

It's better than no antenna.

Carl K9LA
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector