23cm

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How do you get QRV on 23 cm band and what can you expect from this first microwave band

Getting QRV on this band is not very difficult, but as with all bands the better your antenna and equipment, the better results you will get.
The last few years this band has been my most interested band for tropo and aircraft scatter operation.

The 23 cm band runs from 1240 - 1300 MHz

Weak Signal BANDPLAN

Frequency

MHz

Maximum

Bandwidth

MODE

USAGE

1296.000

 

1296.150

500Hz Telegraphy

MGM

1296.00-1296.025 Moonbounce

1296.138 PSK31 centre of activity

1296.150

 

 

 

 

 

 

1296.800

 

 

2700Hz

Telegraphy

SSB

MGM

1296.200 Narrow-band centre of activity

1296.400-1296.600 Linear transponder input

1296.500 Image center (SSTV, Fax etc)

1296.600 Narrowband Data center

(MGM, RTTY,..)

1296.600-1296.700 Linear transponder output

1296.750-1296.800 Local Beacon (10W ERP max)

1296.800

 

1296.994

500Hz Telegraphy

MGM

Beacons exclusive (b)

Most weak signal contacts in CW or SSB are made within the frequency segment of 1296.150 to 1296.280.
During periods of high activity these ranges might be a bit larger.


Equipment:

Equipment for weak signal communications is available on the market

A popular transceiver for the 23cm band is a Kenwood TS-2000X

Afbeeldingsresultaat voor ts 2000x

 

A bit more old fashioned is the FT736r with a 23 cm module

Gerelateerde afbeelding

 

More popular is to use a transverter from 144 MHz (or 28 MHz) to 23 cm

I am using a DB6NT 23 cm Kit, working fine for many years now.

Read the article from ON4CDU and PE1PFW on this kit (Dutch language)

This brings 0.4 Watt output more than enough to drive an RA18H1213G module, good for about 20 Watt

 

A complete ready build transverter is also available at Kuhne Microwave

 

Another transverter is available from SG-lab

or Mini kits

More than enough possibilities to get QRV on 23 cm

Power amplifiers

If you want to work many stations you should have some decent power output, minimum is 10 Watt but better is 100 or more

this one gives 250 W output

Available via : PE1RKI

 

Or one could use an PA build in Sweden at SM4DHN Labetech

For instance this 500 W SSPA

Take a look at his webpage: Labetech

Other option is a power amplifier with tubes,
I am still using an old TV broadcast amplifier with a TH308 tube able to give 250 W or even more depending on PSU up to 500 Watt

Feeder Loss
Feeder loss on 1296MHz can be quite significant. It’s easy to lose over half of
your signals (both ways) through feeder loss. It therefore pays to use good
quality low loss feeder. I would suggest that UR67 should be considered the
absolute minimum, if new feeder is to be purchased. Depending on the length
of run, an even better feeder such as the Westlake 103, Ecoflex15plus or
Heliax should be seriously considered.
In comparison with the lower v.h.f. and u.h.f. bands, it’s very expensive
to generate power at 1296MHz. Don’t forget that it’s almost always cheaper
to use better feeder than try to make up for feeder losses with more power.
Reducing feeder loss is also a ‘big win’ when receiving!

Pre amplifier
For receiving it's even better to have a mast mounted pre-amplifier and coax relay.
For RX you can use a less quality cable and for TX use a very low loss cable.
For TX I am using a low cost bamboo 3 cable length 12 meter which is 75 ohm.
Using a home made tuner I can easily correct VSWR for this.
For RX I use a bamboo 6 cable, no need to correct for impedance error.
My preamp is a home made giving me a Nf off 0,6 dB which is good enough for an antenna aiming at the horizon.
 

Antenna

Get your antenna as high as needed, at least higher than most obstacles in your area.
Obstacles will be buildings, trees etc.

If possible get as much antenna gain as possible, I prefer to have minimum gain of 21 dB but even more is better.
For this I am using a 2.5 meter dish, mounted at 10 meter above ground level.
When using a dish a minimum diameter of 1.5 meter should be considered.
A 2.5 meter dish is good for 28 dB gain, a 1.5 meter dish will bring about 23 dB gain.
 

A 26 element loop yagi would bring about 17 dB

Bild 3

In my early years on 23 cm (1975) I have been using such an antenna, I even build many of these for selling to other hams.
here you can find how this is build

From 1996 on I have been using the 2.5 mtr dish mounted at 10 meters over ground.
It survived many heavy storms up to force 12.

Rotor

The bigger the antenna, the better your rotor system should be, first of all to withstand the forces on it during a storm.
Also important is to have a solid and good indication of the heading your antenna is aiming at.
With a 2.5 meter dish the opening angle of the beam is about 5 degrees,
 so any misalignment will make a QSO more difficult or even impossible.

What can we work

With a good setup one can work quite a lot of stations. Thanks to tropo scatter and aircraft scatter contact over 600 to 800 km
 are always possible with a well performing station.

Just an example what I worked on 23 cm during the October contest 2015

During tropo enhanced conditions, even with a small station, contacts up to 1500 km are possible, but these conditions do not occur that often.
Take a look at my activity page to see what I normally can work

Activity
Unfortunately most of the time there is not much activity, don't expect too much.
This is a typical band with only activity during special occasions.
During contests, activity evenings and special events there is good activity.
During tropo lifts there can be good activity but the last few years this is not that big as in the years 1970 or between 1990 and 2000.
During periods of high activity one can work 30 stations, depending on location within Europe this will differ quite a lot.
In United Kingdom some stations work up to 80 contacts during a 4 hour evening activity night.
Within Europe I guess there are between 800 and 1200 Hams able to be active on the band.
Most active stations have a good system with nice possibilities to work DX.
There are also many stations with only a small setup with possibilities mostly limited to a working range of up to 400 km.

Some signals

during excellent enhanced tropo conditions:

take a listen to the signal from OY9JD

take a listen to the signal from EI9FX, I was his first PA station on 23 cm

take a listen to the beacon OY6BEC on 23 cm

Using Aircraft scatter and normal conditions:

listen to the signal from EI9E/p

 listen to the big signal from OK1KUO on 23 cm Aircraft scatter, 849 km also good signal in SSB

My signal at SP1JNY

SP1JNY at my place

Listen to an aircraft scatter qso with GM4CXM a reflection lasting 4 min