Field Operation, IC 7000 and Buddipole at Champlain Lookout

It occurred to me while reading through the Buddipole information for the Triple ratio Switch Balun (TRSB) that I should be able to make a 20m vertical with a rigid loaded counterpoise.

This antenna configuration would

• have a lower take-off angle as compared to the flattop dipole
• would be directional to a degree
• would be easily rotatable as compared to a wire counterpoise
• would not need a standoff stake for a wire based counterpoise
• would operate very similar to a setup w/ a longer wire counterpoise
  

Modeling

I started with some simple modeling in 4NEC2.


The vertical arm is constructed with 3 dipole arms, 1 red coil, and 1 standard whip. Using more than 1 dipole arm helps make the antenna longer and more effective. The loaded counterpoise is built with a single dipole arm, a black coil and a standard whip.


The antenna is brought to resonance at the frequency 14.1MHz which is what I wanted with the following parameters and settings

Vertical

• Whip fully extended
• Red coil taped 9 turns from the whip end
• 3 standard dipole arms

Counterpoise

• Tilted down at 30degree angle
• Whip fully extended
• Black coil taped 12 turns from the whip end
• 1 standard dipole arms

In 4NEC2 I first assumed the red coil had an inductance of 28.2uH for all 42 turns. This is the value I have used in the past. However with this value, resonance was predicted at only 12MHz. Testing the antenna in the backyard confirmed that the antenna does resonate at 14.1MHz. I temporally centred the model at 14.1MHz by scaling the full coil inductance to 69% of the 28.2uH.


The predicted antenna pattern is as expected for a vertical w/ 1 counterpoise.

Putting it all to use.

Nearby to the city of Ottawa, is a federal park with some breathtaking lookouts. For a Ham operator this looks like very nice spots for an antenna, high up over the surrounding land.



The setup was simple and compact, 2 50AH Gelcells, IC7000, Laptop and the Buddipole



The above 2 pictures show the "picnic table shack" and the vertical. The counterpoise made with the standard whip, coil and arm is raised above the ground and this allows the antenna to be "pointed" and also there is no pesky wire counterpoise to string out.

Operation

There was 070 PSK contest going on and there was plenty to listen to. A big plus of this location is the excellent s1 noise level. Many US stations were on the air as expected but notable and very easily copied stations were from Uruguay, Brazil, Argentina, and a good selection of European stations including, Spain, France, England, and some Russian stations.

QSOs

Thanks to all who helped make this an interesting afternoon. I had some difficulties with the 7000 running a bit hot due to the hot sun. Also, at times there were a few stations who were answering my calls at the same time and I did my best to unravel these situations.

• Start Station Name Country QTH Distance (km)
• 21:34 IK4JQS Maurizio Italy Molinella 6,515.32
• 21:23 PD5DP Henk Netherlands Wolvega 5,681.14
• 21:16 W6DEI Peter USA Berkeley CA 3,893.00
• 21:05 K0WIU Bill USA Yankton, Sd 1,912.58
• 20:49 HA6ZB Gyuri Hungary Aldebro 6,836.85
• 19:53 N4MGA Don USA Rex, GA 1,512.57
• 19:40 N0EPW Simon USA 1,360.02

Thanks to IK4JQS and HA6ZB for the 6000km QSOs. and thanks for stopping by.

Adrien

R8 HF Vertical

(http://www.lairdtech.com/)

Recently I picked up a second hand Cushcraft R8 vertical.

I had the folliwing goals in mind

1. Vertical
2. Multiband
3. No radials
4. Low take off angle
5. WARC bands included
6. Possibility of field day operation
   

• Vertical

Given the layout of the my house's lot, a second antenna would be easier to install if it were a vertical. Also my existing antenna is a 80M to 6M Windom Buxcomm model 802136 and I am intersted in having a vertical to compare. I'll likely never setup a beam so this second antenna will be it.

• Multiband

Multiband is tablestakes, because I need to able to get as much out of an antenna as I can. The R8 is one among very few 8-banders covering from 40 to 6m, WARC included.

• No radials

I like the idea of no radials, mainly because of the ease of installation and flexibility of installation lacation. R8 uses 7 49in stainless radial rods at the base of the antenna.

• Gain and Low take off angle

DX, DX, DX, Low take off angle is important for DX work. With its low radiation angle R-8 vertical should have distinct advantages compared to my windom. The 360 degree coverage should be nice as well.

• Power Handling

The R8 supports 1500W which is plenty for my FT2000D which is a 200W rig.

• WARC bands included

I enjoy digital operation and I often find that the WARC bands have activity, but the Windom antenna does not tune up on 30m for example.

• Possibility of field day operation

The R8 could be used in field day operations but due to its weight it is not easy to get it down without help. Once installed, I think its up there for the long run.

Considerations

• Guying
  

I did guy the antenna down to three points.

• Grounding

I have grounded the mast to a single 8ft ground rod with a run 10ft run of #6 ground wire.

Specifications

Model R8
Gain, dBi 3
Height, m. 8.7
Horizontal rad, deg 360
Power Rating, Watts CW 1500
Vertical Radiation Angle, deg. 16
Band / Bandwidth (kHz) 10m >1500
Band / Bandwidth (kHz) 12m >100
Band / Bandwidth (kHz) 15m >450
Band / Bandwidth (kHz) 17m >100
Band / Bandwidth (kHz) 20m >350
Band / Bandwidth (kHz) 30m >50
Band / Bandwidth (kHz) 40m >150
Band / Bandwidth (kHz) 6m >1500
VSWR at resonance (typical) 1.3:1
Weight, kg. 10.5
Wind Survival kph. 120

The Cleanup

Since the antenna was second hand I had quite a time cleaning up the antenna and setting all the element lengths to the specification.

• I cleaned up external surfaces with a combination of steel wool and lots of work. With this I was able to restore the antenna to showroom look, shine and all.

• The short 6" terminal tuning stubs rods were oxidized such that it was impossible to remove these from the longer stub tubes. I did confirm that all stubs were all stuck in place at the right lengths.
  

• I opened the R8 matching network box and confirmed that there were no mechanical failures of the components inside. A mechanical inspection was complete.
  

• I completely assembled the antenna indoors to see the antenna fit together and confirmed nothing was mechanically broken or missing.

Installation Preparation

• I decided to install the vertical on the corner of my backyard shed. A 2 in pipe was installed up through the roof of the shed.
  
• I decided to guy the antenna from the initial start
• I placed a 1:1 choke at (near) the antenna.
  
• Grounding, 8ft copper clad steel rod at base of mast
  
• Feed line, was 100ft RG/8
  
• Lightning arresor, was placed at the house

Operation

• All bands tune up and better than 1.5:1 on all but the high end of 40m.
  
• Have not tried to see how it tunes on 6m.

RSQ and PSK

A recent look into my own signal quality on PSK made me take a search on the net for information on PSK signal quality.

I came upon this web site (link) which is a site concerned with

"This site is devoted to promoting RSQ as an improved signal reporting system for narrow band digital modes and to demonstrating its application to the popular PSK31 mode."

To this end, they recommend and point out that Regions 1 and 3 have adopted the following

Readability (% of text)
R5 95%+ Perfectly readable
R4 80% Practically no difficulty, occasional missed characters
R3 40% Considerable difficulty, many missed characters
R2 20% Occasional words distinguishable
R1 0% Undecipherable

Strength
S9 Very strong trace
S7 Strong trace
S5 Moderate trace
S3 Weak trace
S1 Barely perceptible trace

Quality
Q9 Clean signal, no visible sidebar pairs
Q7 One barely visible pair
Q5 One easily visible pair
Q3 Multiple visible pairs
Q1 Splatter over much of the spectrum

Seems very reasonable to me and will become part of my operating practices.

PSK Splatter solved

While operating PSK on 20m this morning I received a report that I was splattering across the band. With this in mind I though I should look into this.

I was not operating outside my normal situation.

FT2000D
30W - 80W depending on the QSO
Signallink USB
HP PC
only have 1 antenna, the Windom

Let the experiment begin.

Not knowing how bad the problem was, I went up to 18.1MHz to find a quiet place to poke around.

The only station I saw on the band was a fellow operator here in Ottawa, VE3OIJ. We transmitted back and forth a bit and found nothing remarkable. Leading me to think nothing is seriously broken.

I wanted to see my own signal, so I used the IC7000 to receive the tx output of the FT2000D

Rig
TRX - FT2000D
Freq - 18.1MHZ
Tx Power - 50W (by the FT2000D meter)
PSK Tones - 600Hz

SignalLink
Tx - 3/10

Measurements - HRD on IC7000
Signal S9+20 (input to IC7000 grounded at antenna switch)
IMD - 19dB
SNR - 19dB

Fundamentals 600Hz @ -20dB
Spurs @ 1800Hz @ -70dB 3rd Harmonic
"Image" @ 2900Hz @ -80dB 5th Harmonic
Spurs @ 3300Hz @ -80dB ??

At 6dB/S-unit, if my fundamental was received at his station at S9, then this "splatter" would be received at -S2, i.e. 2 S-units below, S0, these cannot possibly be the splatter my fellow operator saw.


VE3OIJ was able to see these terms, but we are less than 10km apart. It may make sense to follow these terms a bit more. The plot below shows my signal from 1W to 150W into my dummy load. In all cases the relative size of the "splatter" remained fixed. This tells me that these terms are not being generated by the radio's linearity ans regardless of my transmit power would not be a problem to any one but an operator in my city.


How to get gid of these? Don't know.

Next step was to try back on frequency, in case it was RF feedback into the shack that only happens on 20m.

Rig
TRX - FT2000D
Freq - 14.070MHZ
Tx Power - 50W (by the FT2000D meter)
PSK Tones - 600Hz

SignalLink
Tx - 3/10

Measurements - HRD on IC7000
Signal S9+20 (input to IC7000 grounded at antenna switch)
IMD - 19dB
SNR - 19dB

Fundamentals 600Hz @ -20dB
Spurs @ 1800Hz @ -70dB 3rd Harmonic
"Image" @ 2900Hz @ -80dB 5th Harmonic
Spurs @ 3300Hz @ -80dB ??


Identical results.

Below is a typical waterfall on 20m, "strong" signals are 30dB above the noise floor. If anyone else had terms like the ones above in their transmit signals there is no way I would ever see or be concerned with them.



Summary

I cannot improve the relative power in these terms by adjusting my TX power, as they go dB for dB with my fundamental signal.

Only someone in my local area will see these signals as significant, and the operator who indicated I was splattering did not leave his call so I can not tell. I should has asked, but I did not, a short QSO may have been a better idea.

For now I'll assume every thing is ok and go back to having fun.

Update:

Here is another plot of my tx signal.


Update #2

I was in a QSO with a Spanish station and received a 575 report, so again I thought something must be wrong. A plot of my transmit signal is below.

This time I recognized that the "regrowth" was at N times 120Hz, pointing me to a power problem. Also, I though I'd take a look at my CW output as a means to remove the PSK hardware and software from the equation. Below is my CW plot, this was for 10W output.


In my shack I power my table from two power bars. One regular power bar for all the ordinary stuff, PC, lamp, monitors, and a filtered power bar for the FT2000D, DMU2000, and the Kenwood PS-53 for the IC-7000 and / or TS-850. Both power bars are powered from the same wall outlet which has a dedicated 15A circuit for the sta

I can see in the plot above, that the same N*120Hz side tones are present, the first pair are only 35dB down.

Below is a plot of the same CW transmission when the FT2000D + DMU2000 and Kenwood PS-53 supply are on the same power bar as the rest of the shack. (avoiding the MFJ power

I can see in the plot below, that only the first 120Hz side tones are present, but now are 60dB down, a 25dB improvement. The MFJ-1164B power bar will need some further investigation.


In the meantime, returning to PSK mode, below shows a much improved transmit signal.

Rig
TRX - FT2000D
Freq - 18.10MHZ
Tx Power - 130W (by the FT2000D meter, just for testing)

Excellent.



Now I think I have a very good idea of how clean the PSK signal should be from my radio and will keep an eye.

Summary:

1) If you have an extra radio and Signallink you can run 2 copies of DM780 and see your own transmit signal. Grounding the second rig's antenna input will enable enough signal in to be detected.

2) Your AC supply should be suspected if you have N*120Hz sidebands

3) Read an understand how volume controls should be set for your software and PSK interface hardware

4) Looking at your CW output can help isolate the problem

5) a good transmit signal will have better than 25dB IMD, better than 25dB SNR and 60 to 70dB spurious free range.

All for now.

Safety Code 6

As a licensed amateur radio operator in Canada this is my personal interpretation of Safety Code 6. I am presenting this here for any like minded amateur radio operator who is interested in this topic.

Regulations

The Radiocommunications and Broadcasting Regulatory Branch of Industry Canada states in "CPC-2-0-03 Radiocommunication and Broadcasting Antenna Systems" (link) that Health Canada has established safety guidelines for exposure to radio frequency fields, in its "Safety Code 6" (link) publication.

"Safety Code 6" states that current studies in Canada and other countries indicate that there is no evidence that a person will experience adverse health effects from exposure to radio frequency fields, provided that the installation complies with Safety Code 6.

It is my responsibility that my amateur radio station comply with Safety Code 6 at all times.

Safety Code 6

Safety Code 6 recommends general procedures for ensuring that exposure of the general public in the vicinity of RF devices is not greater than the levels specified in this Code. A safety factor of approximately 20 to 50 was incorporated with reference to the scientific-consensus threshold for adverse health effects.

Field Strength Limits (Source Safety Code 6)

Within the 3 to 30MHz bands, a person shall not be exposed to electromagnetic radiation in a frequency band listed in Column 1 of Table 5, if the field strength exceeds the value given in Column 2 or 3 of Table 5, when averaged spatially and over time. The spatial averaging is carried out over an area equivalent to the vertical cross-section of the human body (projected area). A time-averaging period of 0.1 h (6 min) should be employed for frequencies up to 15 000 MHz.

src: Safety Code 6

Canada's National Amateur Radio Society (link)

States that while Industry Canada expects radio amateurs to meet the requirements of Safety Code 6, generally most amateur installations will never exceed the recommended exposure limits. There are many reasons for this including the fact that most amateur installations are operated at relatively low power levels (typically 100 watts), are not on a 100% continuous duty cycle and the amount of transmission time is often limited."

Interpretation

From Table 5

From 1 to 10MHz, Electric field strength is limited to 280/f (V/m) and Magnetic field strength to 2.19/f (A/m).

From 10 to 30MHz, Electric field strength is limited to 28 (V/m) and Magnetic field strength to 2.19/f (A/m).

For each band from 80m to 10m the table below captures the E and H field limits according to the safety code 6 definitions.

I assume 200W output from my rig, which is worst case. 100ft of feed line is assumed with 1.3dB/100ft at 30MHz. To get the losses at other frequencies I scaled the loss by the frequency of each band. I assumed a 3dBi antenna gain which is correct for the Cushcraft R8 Vertical. Effective radiated power is 380W to 290W.

Power density is calculated assuming a worst case 3m distance to the antenna.

For PSK modulation I assumed a 50% time averaging over 6 minutes which is consistent with PSK operation, as I listen 50% of the time, and a typical transmission is much less than 6 minutes. On the other hand I assume duty cycle of 100% when I am transmitting. This factor would be less than 100% for SSB and CW for instance.

Operating Mode	Duty Factor
Morse code (CW)	40%
SSB phone	20%
FM	100%
RTTY/Digital	100%
AM	100%

source: http://n5xu.ece.utexas.edu/rfsafety/power.shtml

I then calculated the resulting averaged E and H field strengths.

Simply taking the ratio of the resulting field strengths and the limits results in a safety margin over and above Safety Code 6.

A copy of this file is available at Google Docs at link.

Limits
Band	(m)	80	40	30	20	17	15	12	10
Freq	(MHz)	4	8	10	15	18	20	25	30
E Field Limit	(V/m)	75	37	28	28	28	28	28	28
H Field Limit	(A/m)	0.58	0.29	0.22	0.15	0.12	0.11	0.09	0.07
Transmitter and Antenna
Output Power	(W)	200	200	200	200	200	200	200	200
Feed line	(ft)	100	100	100	100	100	100	100	100
Feed line Loss	(dB)	0.2	0.3	0.4	0.7	0.8	0.9	1.1	1.3
Antenna Gain	(dBi)	3	3	3	3	3	3	3	3
Effective Radiated Power	(W)	384	370	361	344	335	327	311	296
Density
Distance to Antenna	(m)	3	3	3	3	3	3	3	3
Power Density	(W/m^2)	3.40	3.27	3.19	3.04	2.96	2.89	2.75	2.62
Averaging (PSK-31)
Time averaging		50%	50%	50%	50%	50%	50%	50%	50%
Modulation		100%	100%	100%	100%	100%	100%	100%	100%
Resulting Fields
E Field from antenna	(V/m)	25	25	25	24	24	23	23	22
H Field from antenna	(A/m)	0.07	0.07	0.07	0.06	0.06	0.06	0.06	0.06
Safety Factor
E Field		2.9	1.5	1.1	1.2	1.2	1.2	1.2	1.3
H Field		8.7	4.4	3.4	2.3	2.0	1.8	1.5	1.2
Feedline	dB/100ft	1.3
	MHz	30

Conclusion:

I would state that a Cushcraft R8 vertical at 3m, being fed with a with Rig power of 200W in PSK mode and 100ft of feed line will pass safety code 6.

There are details concerning the Safety Code 6 in the near field which I have not reconciled.

I believe the calculation above to be correct, however all should realize you are accountable for your own calculation, should you attempt to do one for your own station.

Buddipole 4NEC2 Model Files

I have found a way to post my 4NEC2 Buddipole modeling files on line using Google Documents.

Eventually I will log many of my design files here for anyone to use.

4NEC2 is available at http://home.ict.nl/~arivoors/

Below is a list of the files I have created.

FILE AC_Vbud_40M_09_V01 40m Vertical, (longwhip, 4 dipole arms, red coil)
FILE AC_Vbud_40M_08_V01 40m Vertical, (longwhip, red coil, 4 dipole arms)

Detailed Files:

FILE AC_Vbud_40M_09_V01

Description, LongWhip with RedCoil and 4 Dipole Arms on VersaTee w/ TRSB set to 25ohms (2:1) and 1 8.6m Counterpoise.

This is a new configuration
a) attempting to generate a lower takeoff angle and more gain
b) 40m PSK31 frequency (7.07MHz)
c) Red coil was moved to below the arms and whip
d) Suggested by Ray (K7RFW)

1 fully extended Long Whip
4 22" Dipole Arms
1 RedCoil tapped turns from Bottom
1 Versatee
1 TRSB,(2:1) 25 ohms
1 8.6 (m) Counterpoise

Takeoff angle	30	degrees
Gain	0.0	dBi
SWR	1.6	into 25 ohms

Conclusion:
Moving the red coil to below the dipole arms, resulted in a modest loss of antenna gain from 0.6dBi to 0dBi, the take off angle remained the same at about 30degrees. The inductance needed to maintain the antenna at resonance (7.07MHz) was reduced from 15uH (18 turns form the bottom) to 10uH (25 turns from the bottom). Best case SWR was increased from 1.1 to 1.6 as the impedance of the antenna decreased from 22.5ohms to 15.6ohms.

Overall, I would take from this, that is it better to not have the coil placed adjacent to the feed point.

-------------------------------------------------------------------------------------

FILE AC_Vbud_40M_08_V01

Description, LongWhip with RedCoil and 4 Dipole Arms on Versatee w/ TRSB set to 25ohms (2:1) and 1 8.6m Counterpoise.

This is a new configuration
a) attempting to generate a lower takeoff angle and more gain
b) 40m PSK31 frequency (7.07MHz)

1 fully extended Long Whip
1 RedCoil tapped 18 turns from Bottom
4 22" Dipole Arms
1 Versatee
1 TRSB,(2:1) 25 ohms
1 8.6 (m) Counterpoise

Takeoff angle	30	degrees
Gain	0.63	dBi
SWR	1.11	into 25 ohms

-------------------------------------------------------------------------------------

Special QSL Cards

Two new QSL cards will be on their way.

For the winter camping "DX-pedition" I made up the card below, it shows the Yurt, and the cozy operating station inside. The globe was generated from Google Earth through Ham Radio Deluxe and the IC7000 radio image complete card.


I've been running the call GC3IAC since the beginning of February in celebration of The International Year of Astronomy. The special prefix call sign starts 1 Jan 09 and ends 27 Feb09 23:59 UTC

VE changes to CG, VA changes to CF, VO changes to CH, and VY changes to CI



I have not posted these in the mail but I will in the next few weeks.

73