Tag Archives: Station Building

It’s All About The Decibels – Factors In Enhancing Station Effectiveness

Reposted By Layne AE1N

In electronics and communications, the decibel (abbreviated as dB) is a logarithmic expression of the ratio between two signal power, voltage, or current levels. In acoustics, the decibel is used as an absolute indicator of sound power per unit area. A decibel is one-tenth of a Bel, a seldom-used unit named for Alexander Graham Bell, inventor of the telephone.

Suppose a signal has a power of P1 watts, and a second signal has a power of P2watts. Then the power amplitude difference in decibels, symbolized SdBP, is:

SdBP = 10 log10 (P2 / P1)

This is much easier to understand by observing the table below.

1  dB ~ 30 percent increase

2 dB ~ 60 percent increase

3 dB ~ 100 percent increase

6 dB ~ 400 percent increase (~ 1 S-unit)

NOTE: For purposes of this article, our “Zero-Point” is a modern SSB transceiver running 100 watts to a half-wave dipole up about 30 feet. The objective is to improve station effectiveness in any various ways:

-27 dB ~ Switch from CW to AM

-17 dB ~ Switch from CW to SSB

-14 dB ~ Switch from CW to FM

-12 dB ~ To protect final transistor blow out manufacturers recommend reducing power to one-fourth normal when switching from ‘intermittent modes‘ (CW, SSB) to ‘Key-down’ modes (AM, RTTY, Digital).

– 4 dB ~ Switch from CW to RTTY.

+2 dB ~ Switching from FT8 to JT4. FT8 is operationally similar but four times faster (15-second T/R sequences) and less sensitive by a few dB. (On the HF bands, world-wide QSOs are possible with any of these modes using power levels of a few watts (or even milliwatts) and compromise antennas.

+2 dB ~ Switching from JT9 to JT9A. JT9A is 2 dB more sensitive than JT65 while using less than 10% of the bandwidth.

+2 dB ~ 2 Element collinear arrays.

+ 2 dB ~ single Cubical Quad loop.

+2.2 dB ~ 2 Element end-fire array 0.125 wave spacing.

+2.8 dB ~ 2 Element broadside array 0.64 wave spacing.

+ 3 dB ~ the ambient noise level has a profound effect on your ability to hear weaker signals. The following data was from VOACAP. VOACAP (Voice of America Coverage Analysis Program) is free professional HF propagation prediction software from NTIA/ITS, originally developed for Voice of America:: For 100 watts to a dipole at 33 feet located in grid square FN42 on a path to Central Europe at 1800 GMT. The following circuit probabilities are shown based on noise level at the receiver site: Quiet 55%; Rural 53%; Residential 42%; Industrial 26%; Noisy 23%. It appears that a noise quiet area has a 3 dB advantage.

+3 dB ~ 5/8 wave vertical vs. ¼ wave vertical hence the popularity of the 43 foot vertical.

+3 dB ~ Extended Double Zepp antenna.

+3 dB ~ Raise power from 100 to 200 watts.

+3 dB ~ vertical stacking of 2 identical antennas (0.5 to 0.75 wavelength spacing).

+3.4 dB ~ Moxon antenna.

+3.9 dB ~ 2-element Yagi parasitic director.

+4.3 dB ~ 13-32 MHz Log Periodic.

+4.5 dB ~ 4 element collinear array.

+6 dB ~ Raise power from 100 to 400 watts.

+6.6 dB ~ Rhombic 2 wavelengths per leg.

+6.8 dB ~ 4-element yagi beam.

+7 dB ~ Switch from CW to PSK31.

+7.3 dB ~ 2-element Cubical Quad.

+7.5 dB ~ 10 wavelength long wire at peak lobe.

+7.9 dB ~ 5-element yagi beam.

+8.5 dB ~ 6-element yagi beam..

+8.7 dB ~ 3-element Cubical Quad.

+9 dB ~ Raise power from 100 to 800 watts.

+10 dB ~ 3-element tribander.

+10 dB ~ Rhombic 4 wavelengths per leg.

+10.5 dB ~ 4-element Cubical Quad.

+11.1 dB ~ 11-element yagi beam.

+12 dB ~ Raise power from 100 to 1500 watts.

+13.4 dB ~ 19 element yagi beam.

+20 to 25 dB ~ switch from SSB to CW. It is mostly the signal-to-noise (S/N) improvement on the receive side that gives you the advantage on CW.  Assume a 2.5 KHz receive filter needed for SSB, and a 250Hz receive filter used for CW.  Now you have a 10dB advantage.  However, it is also easier to hear a CW tone than it is to understand SSB in a noisy environment.  I.e., the required S/N for CW copy is lower than for SSB copy. So, add a few more dB advantage to CW.  So, a rule of thumb is that CW has about a two S-unit (12dB) advantage or so over SSB. A 100-watt CW signal is equivalent to a full legal limit SSB signal. 20 to 25dB is a reasonable expectation for seasoned CW ops when the entire system includes the operator.

+25 dB ~ Switch from CW to FT8.

+25dB ~ Switch from CW to JT65.



These charts are from “How Much ‘Punch’ Can You Get from Different Modes?” by Kai KE4PT and Bruce N0ADL in QST, December 2013.

COMMENTS – Any change in power has no effect on receiver capabilities. Antenna gain figures are typical for that type of antenna. No cost/benefit attempt is made here. Most hams have limited pocketbooks. Besides marketplace prices are ever changing. And time is limited. Elevating you vertical slightly and installing 4 radials is a lot faster than laying down 120 radials!                                      73,  Layne AE1N



Remote Control Ham Station Enhancements

As explained in a previous article, we have been working on enhancing our Remote Control Ham Station system. The upgrades include additional remote client options, better remote networking via the Internet, and better integration with our microHAM system.

Source: Remote Operating Enhancements | Our HAM Station

As part of the fall upgrade plans at our station, we have completed quite a few enhancements to the Remote Operating Gateway and associated client devices in our station. The upgrades include:

You can read more on our Stationproject Blog about our Remote Control Ham Station Enhancements.

We try to do some station upgrades in the fall of each year to maximize our operating fun during the winter months. We always welcome members who want to join in on our projects as a means to learn about station building. More to come as we make progress with our planned projects.

Special thanks to Dave, K1DLM who has helped us with ideas for several aspects of this project.

Fred, AB1OC

Plans for Enhancing Our Ham Station This Fall

Source: Plans for 2017 Station Upgrades – Radio, Shared Amplifier, and Remote Op Enhancements

We are planning a number of enhancements at our Ham Station this fall. Our plans include:

We try to do some station upgrades in the fall of each year to maximize our operating fun during the winter months. We are at the design stage on these projects and I wanted to share some information about what we are planning from our Stationproject Blog.  We always welcome members who want to join in on our projects as a means to learn about station building. More to come as we make progress with these projects.

Special thanks to Dave, K1DLM who has helped us with ideas for several aspects of this project.

Fred, AB1OC

A “Tech Night” To Remember – Our Visit To KC1XX

Our August “Tech Night” featured a Saturday visit to the Matt Strelow, KC1XX’s superstation. Matt’s station sits on top of a mountain in Mason, NH.

Matt Strelow, KC1XX’s QTH

Our visit began with a tour of Matt’s antenna farm. Matt has a total of 13 towers and each one has a unique story and purpose.

300 ft Tower at KC1XX
300 ft Tower at KC1XX

Matt’s tallest tower is used for 80m as well as other bands. It is painted red and white and has a light on top!

Antennas and Towers 5
Base of Rotating Tower at KC1XX

Several of Matt’s towers are rotating ones with some serious tower turning hardware at the base.

Antennas and Towers 2
Rotating Tower Guy Rigging

Rotating towers use a special type of guy attachment ring which allows the tower to turn while being supported via guy wires.

Coax Feedlines
Coax Feed Lines at KC1XX

Matt has built an extensive infrastructure which supports all of the antennas at his QTH. The picture above is a small building where all of the feed lines from Matt’s antennas enter his station.

Dennis, K1LGQ Operating at KC1XX
Dennis, K1LGQ Operating at KC1XX

After the tour of the antenna farm, we saw the KC1XX “shack”. Several of us had a chance to operate Matt’s station. How’s this for QRP Dennis?

Abby, AB1BY Operating at KC1XX
Abby, AB1BY Operating at KC1XX

Abby wasted no time in building her usual pile up. It easy to see why KC1XX has a pile up whenever they are on the air after just a short time spent operating from there.

Nashua Area Radio Club "Tech Night" Group 2Nashua Area Radio Club "Tech Night" GroupKC1XX QTHDennis, K1LGQ Operating at KC1XXDennis, K1LGQ Operating at KC1XXAbby, AB1BY Operating at KC1XXAntennas and TowersAntennas and Towers 2Antennas and Towers 3Antennas and Towers 4Antennas and Towers 5Antennas and Towers 6Antennas and Towers 7Antennas and Towers 8Antennas and Towers 9Antennas and Towers 10Antennas and Towers 11Coax Feedlines

After a great day of fun and lots of picture taking, See the gallery above for more pictures. Matt treated us to refreshments and some more conversation about his Amateur Radio experiences.

Nashua Area Radio Club "Tech Night" Group
Nashua Area Radio Club “Tech Night” Group

All of the members who made this memorable “Tech Night” had a great time and we’d all like to thank Matt for his gracious hospitality. We learned a lot!

Fred, AB1OC