Solid Improvement on 1296MHz.

A little while ago I found a power amplifier for my 1296MHz setup.

This is essentially a W6PQL design with improvements and control/safety circuits by OZ2ELA.

A group had built this as a project, and one of the participants lost interest and sold the unit.

A test showed a solid output of 80 - 90W, enough for my purpose.

Controlling the mast preamplifier through the coax was not available, so I got myself 2 high power bias-tees for 1296MHz, capable of handling 600W.

Now I can bypass the DC control voltage from the radio to the preamplifier, and still use the PA as TX amplifier. This works well, and I am now running 50W on 1296 most of the time, with a drive of 3W from the transceiver.

I do have some cable loss, so often I could hear people who did not use mast preamplifiers at the antenna, but they could not hear me. With the amplifier, now there is a better balance between the local (FM) stations and my station.

There is still a lot to optimize here, mostly with respect to antennas and cable loss, and now the spring is coming, I can get started with that.

At the moment I am using a vertical monoband 1296MHz antenna. 

Some yagi or other directional antenna is in the planning for use with DX (SSB/CW/DIGI modes, or even FM), and I do have some decent cable available for this purpose.

New Vertical Omnidirectional Antenna for 23cm.

Finally, today I got my new mono-band vertical omni-antenna up for 23cm. I was using the 3-band antenna X-7000 from Diamond on 23cm, only and it had one serious drawback. The signal into the preamplifier from an adjacent antenna a few meters away was killing the GaAsFET in the preamp.

The second srawback of the X-7000, also connected to the 3-band configuration, is that the gain of the antenna on all bands, and 23cm in particular is not fully optimized, and it probably does not radiate so much from the top end.

The X-7000 is nabout 5m long, and the new F1-230A II is only 3.5m long.

The new antenna has been mounted about 1.5m higher, with the feed point about 7.5m, and the old X-7000 was at 6m. The tip of both antennas is approximately 11m, so I suspect that the radiation from the new antenna is located higher in altitude.

The new antenna was intended to be raised yesterday, but it got caught in branches of nearby trees. Those trees ahve now been trimmed, so today we could finish the work, and make a test of the new antenna system.

A fresh preamp has been mounted, so the receiver sensitivity is back to the optimum, and a transmit test revealed improved signals from stations in several directions. OZ1GIN who could only hear an extremely noisy signal before, can now read my signal with an Okay-ish signal.

I can still improve the transmitter capability with a power amplifier module, probably increasing the power at the antenna from about 5W to about 25W.

Given that many stations do not work with preamplifiers near the antenna, this should be a solid improvement of my station range.

This is the best I can do with an omnidirectional vertical, so the next 23cm antenna project will be getting a modest 23cm horizontal antenna up on a rotator as high as I can. As far as I can see, I can get a small yagi up about 11.5 - 12m, and with a good preamp and decent linear amplifier that will be what I can achieve. 

It should be a decent setup at my QTH, the best I can do. 

As the small yagi is "front mast" mounted, I might add another one, vertical, in the opposite direction, when I can repair one of the3 destroyed preamplifiers. Yes, I have ordered new GaAsFETs.

For now I have the vertical omni-system to work with, and I think I will have some fun with that.

Back on the Local FM Frequency on 23cm.

Today a local ham came here and assisted in getting the 23cm vertical up and running.

My X-7000 antenna is now mounted with the feed point 6m above the ground.

A quick test showed decent signals at a distance of about 40km, so the system is working well enough.

I can still hear the OZ7IGY beacon, even though it is horizontally polarized.

Now I need to get some more antenna work done before winter. 

Focus will be on 23cm, because it's a fun band and we need to use it or lose it.

Second band focus will be 6m, as we might get into an autumn season with very high solar activity in the comning winter half of the year

23cm Antenna Stuck.

 I need to check my 23cm antenna system again. 

I have a helical mounted on the mast with a small AR-500 rotator.

This has worked for a while, and now the antenna is stuck in (about) 180 deg. The rotator seems to turn, when I look at the antenna outside, nothing happens.

Oops!

As a temporary solution until I can get a rotator running, I am thinking of using my old vertical, the Diamond X-5000, so, at the least, I can work on out local net on 1297.500 FM. 

A local ham has offered to help with that, so in a few days I should have that up and running, at the least.

Now, if the rotator is ruined, that was a very short life span. We shall see what I can do. In the worst case, I will have to purchase a new (bigger) rotator.

1296 Antenna.

 A local ham sold two helical antennas for 23cm, and I went to get them. The price was good, and the antennas looked good, and ready to mount in the mast.

Now I am waiting for the opportunity to mount at least one of those antennas in place of the horizontal yagi. 

For this I need the combination of good weather and a ham friend or two to assist.

I suspect the results will be similar with stations using horizontal yagi antennas, and an improvement to local stations using vertical antennas, as the helical should have a slightly higher gain, offset by a 3dB loss in signal strength as is usual when using a circular polarized antenna with a linear polarized antenna.

The weather forecast looks decent, so I hope I can get it done within a week. We shall see.

1296MHz Improvement. Antenna Height.

 For a while I had my 1296MHz yagi mounted at a height of just 4m above ground. I could detect the DB0VC beacon in Kiel, about 200km distant, not constantly but every day I made the attempt.

On Easter Sunday I had a local ham help erecting a telescopic mast of 6m. This means that witg a little help from a friend it is possible to make antenna experiments for the higher bands. The rotatyor used is a small AR-500TV antenna rotator, and it works nicely with the small 1296MHz yagi.

The antenna is now 7m above ground (30m ASL), and I could detect a considerable improvement compared to the lower position, in some directions. In other directions there are still obstacles.

At the first test with 7m height 4 local stations were immediately heard, within about 10 minutes of starting operation on 1297.5MHz FM. This is encouraging. The furthest station was near Malmoe, Sweden, at a distance of about 30km, and while my yagi was horizontally polarized, and he used a vertical, we could get some fading signals. I suspect the fading, which came with very regular intervals, was due to some wind turbines along the path.

The beacon DB0VC is now heard a bit more regularly, and today I noticed something that I did not hear with the antenna at 4m. Several aircraft reflections were clearly audible, with the characteristic Doppler shift frequency change.

Today I also got a new station, running at a distance of about 20km, just running 4W, with the ADALM Pluto SDR and a front end with 4W output, running from a balcony with a home made 7 element yagi. Good signals, as we were both working with horizontal antennas.

For all this I used the IC9700. I also have a IC910 with a 1296MHz module.

Future developments:

Two more things are now needed to improve my system on 1296MHz:

- A good vertical antenna as high as I can get it. I intend to use the IC910 with this antenna, and a preamplifier near the antenna, just like with the yagi. Most likely the X-5000 from Diamond, used with a triplexer for multiband operation on 2m/70cm/23cm, with preamplifiers for every band.

- a power amplifier for each antenna/radio system. For the vertical/IC910 I intend to get a relay/sequencer up and running, so I can get about 25W at the antenna. For the yagi, I intend to get a maximum of about 75W at the antenna. I don't have the amplifier for that yet, but I will get one when I can.

Fault in the 23cm Antenna System.

There seems to be a fault in my temporary 23cm antenna system.

The signal disappears intermittently, and I suspect a fault in the connector for the cable bypassing the rotator. I have ordered better cables and N-connectors, so as soon as possible that cable should be replaced. Another option could be intermittent voltage to the preamplifier from the radio (IC9700), but the cable/connector fault is the most likely.

I will need to get some assistance from some local ham(s), as the antenna should be mounted about 2m higher, still in a temporary position. I cannot do that alone. The risk of damaging the antenna is too high.As the antenna is standing in my backyard and surrounded by houses and trees, every meter in height will help, so it will be interesting to see how much the signals will improve.

At a later stage I epxect to mount the antenna in 8-9m height. That is what I can do here. There will still be trees in the way in some directions, but it should be above houses in most directions.

Intermistic 1296MHz Yagi Setup.

The past few days I have worked getting a bit of activity going on 1296MHz.

The antenna is a Flexa Yagi model with 16 elements, for mounting behind the reflector.

The mast at the moment os just some military stackable pipes, and I could not handle more than 4m length alone, so that is the height of the antenna right now.

Results are varying. A station about 20km away could not hear my 5W at the antenna. He is in a poor direction, as the signal has to pass through my house, so maybe not too surprising.

We have had a bit of tropo propagation, so the beacon in Kiel, about 200-250km away is quite strong. In that direction the antenna points over free fields, and at the moment the signal from DB0VC is S9. During the day it was audible at all times. 

I do have a preamplifier near the antenna, so reception is quite decent.

At a later stage the antenna can be mounted at about 8m height, but the results are encouraging.

I did try to send a few CQs on 1296.200, but no replies. 

In the SE direction I can hear very strong radar signals, S-meter shows up to s9+30 in the peaks.

Next step will be getting the antenna higher up and see what happens. I will need assistance from some local hams, so it may take a little while.

23cm Vertical Antenna. New Cable.

 Yesterday I reacted to an ad from an amateur less than 100km away, for some 1/2" low loss coax cable.

I got two pieces of close to 20m length. The loss is considerably lower than the previous cable, somewhere around 1.6dB. One of the cables has a set of M/F N-connectors and was ready for use.

Today I got a visit from Kent, OZ2KC, and we got a new experimental vertical antenna setup done. Yes, this is a temporary setup, but good for testing the improvement, and I still need to make the rotatable horizontal antenna. But for some local tests with other vertical/mostly FM stations this is more or less the best I can do right now.

The improvements are as follows:

- The cable los has been improved considerably, a difference of more than 6dB.

- The height of the feed point has been raised a bit.

- The antenna is now essentially free of the branches of the tree next to it.

A test with a local station showed a solid improvement, but more tests are needed with mpore distant stations. The top of the antenna is now close to 11m above ground, and the view from the antenna is relatively free in several directions, like SW to E, less so in other directions. SOme of the neighbour's houses will shade part of the antenna, but very little will shade all of it. This is the best I can do at this location.

The second cable has no connectors yet, and I need to find some, so I can get to mount the horizontal antenna, too.

A different option could be a different antenna setup with the vertical and the horizontal antennas switched. I will have to think a bit more about this, as I would like to use both antennas simultaneously, at least for receiving.

More on the results as the tests continue, and more on the planning for other antennas as I do more thinking.

Small Improvement of the 23cm Antenna System.

The past few days I got all the parts located for my X7000 antenna. This is a 5m long 2m/70cm/23cm vertical, so it should have a decent performance when used for 23cm alone. Today I got the X5000 (1.8m long) antenna replaced with the X7000. The feed point is a bit lower for this one, but due to its length the top of the antenna is about 2m higher than that of the X5000 was.

I also got a preamplifier mounted close to the antenna, but due to the high cable loss (maybe less than 10dB) the effective TX power is not much more than 1W, and the feed point is rather low, about 4m.

The signal strength of the "local" beacon is a bit higher on average, but not significantly, probably mostly due to the cross polarization loss.

The first experiment was with the usual local stations, and the received signals were not surprisingly well improved. The transmitted signal was improved, too. Progress.

A test with a station a bit further away was a part success. I could hear the station intermittently (sounded like a mobile station with flutter/fading), but no reception of my signal.

More tests are needed when other stations become active and available for experiments.

23cm Experimental Antenna Setup. Success.

The past few days we had decent weather, so I have worked a bit on setting up an initial 1296MHz antenna.

I have a Diamond X5000 antenna that I decided to use for this. This one is a 1.8m (6ft) long vertical. I used some stackable (mil) mast pieces, so the antenna feed point is now around 4.5m up.

I used the cable I had already. 13m of RG213, connected to the antenna and with a PL259 (sic) connector at the other end. Then another 10m cable of the 400 type (very stiff, just over 10mm diameter).

A rough estimate of the cable loss would be 6-10dB.

Even with this rather poor setup I could hear the OZ7IGY beacon on 23cm, easily readable. The beacon is only 26km away, but uses a horizontal antenna, and is located behind some hills from my location.

The system works, for sure.

This evening OZ2KC and I made the first test with a decent antenna setup here, and even if the distance is only 6km, it is a good test. Signals were S6-S8, fully quieted with FM. Later there will be more tests with more distant stations, of course, but this is a good start.

The second test was reducing power from the IC910s (we both have one) to the minimum possible. We could still work two-way.

Test #3 was trying the hand held transceiver with about 300mW out. That provided a slightly better signal than the IC910 at minimum power. I estimate that the minimum power out on 23cm with the IC910 is 100-200mW. With 6-10dB cable loss the QSO was actually possible with about 20-30mW at the antenna. The system really works, and there are more improvements to make.

This was a good day.

There will be better antennas coming up this year when the weather gets better, and I can assemble the necessary material.

1) The vertical (or another one) could be placed higher for better coverage.

1a) If I can find the supporting pipe, I can set up the X7000 antenna. This one is 5m long and has even more gain than the onbe I used today.

2) As I need long cables to put the antennas in suitable positions I am planning on several improvements to the antenna system:

2a) Getting a good preamplifier mounted near the antenna

2b) Getting a power amplifier near the antenna, so the full 10W can be radiated. I do have a suitable 10W module for this.

3) For use with SSB/CW for DX work I need a horizontal antenna with some gain, and a rotator system. I am also considering using a 25W power amplifier near the antenna, along with a good preamplifier, and mounted as high as I can without it being too visible.

Along with that, there should be experiments with getting some 2400MHz and 10GHzup and running. First experiments should probably be portable from a higher altitude than I have. Initially I just want to have at least one QSO done on as many bands as possible.

Portable Antenna for 23cm.

 I located the old 12 element Yagi antenna I had lying around and made it ready for some portable operation on the band.

I found an old photo tripod that had lost the mounting plate and used the simplest possible method of attaching the antenna: Duct tape. Yes laugh away, but it is good enough for a few tests I want to do, but of course a better mounting is needed for more stability of the setup.

As thing are now, I can go out on a hilltop (or other place with a good view) and operate 23cm FM at horizontal polarization, but just 300mW from the handheld transceiver. This can be carried easily on to a hilltop, also with a few spare batteries, and a few experiments can be done.

I do have a mobile transceiver, the TM741 with a 23cm module. I need to test that and if it is still in good working order I will have 10W output.. This can be easily used from the car, with a 12V battery. The 12V battery of the EV is not suitable, so a better battery is needed. This I cannot carry around easily, so hilltops not accessible by vehicles are not in my thoughts unless there will be two people carrying the equipment.

The old transverter I have also needs to be tested, and if it is in good working order, 5-10W SSB/CW operation. As IF transceiver I can use my old IC202 or the FT817. Both need a modification to control the transverter.

For home operation there is much more work to do, as nI will need a good vertical setup and the 16 element yagi on a rotator, too. hat will take a bit longer.

My crystal ball shows a bit of 23cm activity in my future ;) .