Category Archives: Amateur Radio

Restoring memory settings in FT817

After getting my FT817 final stage replaced, and all power settings reset to meet spec, I started to use the radio again and quickly realised that all the memory settings (frequency and mode) had been wiped.

This made it necessary to change bands using the band switch (!) and manually change between SSB and CW mode, or occasionally FM, dialing up and down the band as necessary.  With the frequency settings in memories, I only needed to move between memory channels to go from SSB on 7090 to CW on 7032, for example.  And on higher bands, I had several beacon frequencies stored in some memories, allowing me to quickly move between the various 10m and 6m beacon frequencies to get a quick impression of band conditions.

So today I dug out the details of the FT817 memory manager software, retrieved the file of frequency settings stored on the computer, added a few new ones and saved the lot in the 817.   Then repeated the process for  my second FT817.  So they now have an identical set of frequencies in their memories.  Makes them somewhat interchangeable.

All the second radio is missing is a cw filter.  I have plans to sort that out soon.

The details of the memory manager and how to interface it with the radio from a windows box are all in a previous post to this blog.  I actually read the post to remind myself of how it worked!

The previous post on this topic is here.

The blog documents it all.

 

Sotagoat app on iOS – workaround for “alert” time error

The SOTAGOAT app is a well presented and popular app for iOS and works well on my iPhone 5s and the iPad.

Its features include displays for alerts and spots, just like the sotawatch.org website, configuration options allowing you to choose between UTC and local time for displays and posts, an option to produce a goat bleat when each new spot is received from sotawatch, a filter option to specify which modes you want to be informed about and the time periods in which you want the notifications and bleats to occur. It uses an internal list of summits which can be updated from a sotawatch site and can display a list of summits near to your current location, which it gets from the GPS info in the phone or tablet.

However, the current (2016) version of the app has an error in the time calculations for new alerts. Sotawatch uses UTC dates and times. I have sotagoat set to display and post in UTC.  But the times posted and seen on sotawatch were always incorrect and I observed that they were incorrect by the UTC offset. The app was adding my UTC offset to the UTC times I wanted and then posting the adjusted time to sotawatch.  I have found the error can be worked around by adjusting the alert time as follows.

When posting an alert I subtract my UTC offset from the alert time.

For example to post an alert for 2300 UTC I subtract 11 hours (in DST periods) or 10 hours (in standard time) and post the alert for the adjusted time, namely 1200 UTC.

This is easy for UTC times after 1100 but for earlier times, the date must be adjusted back too. It’s simple arithmetic you can do in your head. For say 0400, subtract 11 hours: I do that by one of these two methods:

  • First subtracting 4 hours to get back to 0000, then subtracting the remaining 7 hours (because 4+7=11) from 2400 to get 1700.
  • Add 24 hours to 0400 (2800) and subtract 11 hours from that (1700).

In each case, because the time is in the previous day, subtract one day from the date too.

What if I was in a time zone that is behind UTC instead of ahead?

I don’t know whether the software error treats both time offsets similarly. It is possible that it is correct for negative offsets.

The error has been notified to the author of the software but as it can take a while for new versions to be released via the iTunes Store, I will use this workaround until it is fixed. The utility of the application is too good in all other ways to stop using it.

SOTA QSO Party 22nd October 2016 at Bobbara hill

My station setup for this event was later than planned.  My original summit was to be VK2/ST-042 and to get access a phone call to the owner of the access road is usually all that’s required.  However after two phone calls getting a voicemail response and no callback, I decided to go to Bobbara Hill, just west of Binalong, although that required a longer walk time as well as an extra 20 minutes of travel time.
Once I left the car, opened and closed the gate and starting to walk along the track leading to the hilltop, I was surprised by the wind strength even on the valley floor.  As I climbed further I found the wind was even stronger on the hilltop.
I started setting up in the eastern side of the hill which happily allowed me to avoid the wind, but when I lifted the antenna pole up into the wind it was being blown around so vigorously in the turbulence that I decided it had no chance of surviving in that position and I moved everything further around to the east side of the mountain.  More delay.
Finally I got on the band and called cq on cw, then worked 12 contacts, many being S2S.  I tuned around for ssb activators but apart from Don M0HCU didn’t hear many.  I did call some but lost out to Europeans.  Looked for Ed DD8LP lower in the band where he was spotted but nothing there.  Twice the pole collapsed mid-contact.  Very difficult especially on a slope and in that wind.
I forgot to spot myself but while the contacts are coming you don’t need more qrm.  I have a 250 hz filter in the 703 but that wasn’t narrow enough to sort through the signals at one stage.  Have to say my sending was affected by the unseasonably cold temperatures, not sure exactly what the temp was, but less than 10C, possibly down to 6C or so by the time I finished.  Others were making mistakes too.
Found the tablet was ok for logging but on cw it is tricky to log an incoming call as it happens.  Pencil and paper are easier for that…
Bobbara Hill looking west
Bobbara Hill looking west
Bobbara Hill SOTA setup
Bobbara Hill SOTA setup
I worked 12 contacts, DL3TU, VK4BJS, HB9FVF, OK2PDT, DL3HXX, DL4CW, HB9DQM, OE5AUL, CT7AGR, HB9AFI, JP3DGT and M1EYP just after sunset. Thanks to all.
The surprise was to finally work Tom M1EYP as my last contact and then I looked up and realised the light was fading fast so I packed up.  Walking back down the hill, I was in near darkness as I approached the car half an hour later.
The next morning I received an email from CT7AGR, Portugal, a very nice message thanking me for the contact.  I was just relieved to make the 12 contacts I did including 8 as Summit to Summit (s2s).
 Update: received another email re the S2S contacts.  S2S are the most desirable of all the sota contacts.

Using the Wifi hotspot from an iphone for the android tablet

I was having some trouble getting reliable linking to provide the android tablet (a Lenovo Tab3/7) with internet access while on hilltops or in parks.

A bit of research found a lot of wave-away-the-problems type of solutions, which didn’t solve it at all.

Finally I discovered a comment about the type of hotspot that the iphone actually provides.  It is not an infrastructure type but an adhoc hotspot.  And more to the point, it does not advertise it continuously.  It only advertises the hotspot for a limited time after being enabled, or after you visit the Personal Hotspot option in the Settings menu.

After some experimentation I now find that the tablet happily links to the iphone every time, provided I go to the Settings > Personal Hotspot item in the iphone and then wait about 10 seconds.  Nothing else needs to be done, provided the wifi password has been set in the tablet.

The other solution I have used from some hilltops is to take a personal hotspot device with me.  As my phone provider uses a provider that does not have as good coverage as Telstra, this provides my tablet with excellent network coverage from places without any service on the other network.

Here’s a pic of the hotspot lashed to a tree on the Boboyan Range summit, 40 km south of Canberra.

 

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Telstra hotspot, tree mount variety.

Preventing the “power spike”

This problem was discussed on the moon-net list in May-June 2016.  I thought it was worth documenting what is going on with many radios that produce a “power spike”.

The problem is that the gain of the amplifier chain (from say, final mixer to output) will vary from rig to rig, also the drive level will vary. Therefore the actual gain required of the amplifier chain varies from rig to rig, purely due to component variations and even due to alignment settings, which are probably done fairly quickly at the factory.

The use of ALC to control the gain of the amplifier chain is a typical and common approach taken by manufacturers. It is a technique that does not work very well for modes other than FM and where external amplifiers are used, where the output power required is less than the maximum rated power of the radio (actually, less than about 1.5 X the rated power).

Other manufacturers also have these problems. They address them in different ways.

In one example, the Yaesu FT8*7 series, there are two controls for each band set (HF, VHF low, VHF high and UHF), being drive gain and output power limit.

Another example is Icom’s IC910 where I understand that the power level control has a dual action, one is to reduce the amplifier gain and the other is to change the output power limit level. So it achieves the same kind of result as the Yaesu 8*7 series, and should result in no power spike when first transmitting.

In any radio, if the driver gain is too high, the output power may momentarily exceed the preset level intended from the radio and set by the power level preset feeding the ALC circuit. The time constant of the ALC circuit determines the attack and delay times but cannot prevent the power level rising above the preset value, momentarily, and that’s all we need to exceed the limits of a solid state amplifier device.

So in the 8*7 series you can set the gain level appropriately so that the radio cannot output any more than your chosen power level, and it is a matter of alignment procedure to adjust output limit and stage gain appropriately to get the result you want. They do (cleverly) offer three power levels and you can set the gain and the output power limit for each power level.

For a radio capable of 100w output it is never going to be enough to set the output limit (driving the ALC) to (say) the 25w level. As already stated, that will still result in a power spike while the ALC sets the output level to what the user requires (via the output power control). It is more obvious and easiest to see in the constant carrier modes like fm and CW.

If the drive level is sufficient to allow the power amp chain to produce 100w, then the initial output (on say CW mode) will be 100w, and if you have set the output limit to 25w, feedback via the ALC circuit will reduce the power to 25w. But the initial spike will always be there. It may only last a few milliseconds, but with solid state circuits it is not a matter of heat or averages, it is whether the input voltage exceeds the correct level at all, for even the first sine wave at 144 MHz, ie. for 1/144 microseconds.

What produces the spike? There is enough drive to the final amplifier for 100w. The output limit setting may be set for a lower power level, if so the ALC line is used to send a gain control voltage back to the gain controlled stage(s).

To make it impossible for a power spike to be produced, the drive level has to be reduced. We need to limit the drive to the power amplifier chain to whatever is needed to produce the nominal power level, whatever it is, 1w, 25 or 75. This could be done in several ways.

The first and typical way to reduce the drive level, when using audio source and ssb mode, as for WSJT and other AFSK type modes, is to reduce the audio level going into the radio.  This would work, but if the reduction in drive required is significant (more than say, 10 db) that decreases the signal level without reducing the level of noise and other inevitable spurious signals, including the suppressed carrier of the ssb signal.  Eg a carrier suppression level of 45 db may be specified by the manufacturer, referenced to its performance at full rated power.  By using the audio drive to reduce total output we are accepting that the suppressed carrier can remain at its current level, and that may be ok for some radios.

The second method of reducing the output is to use a high power attenuator between the radio and the external amplifier.  This attenuator would be in that circuit on receive mode too.  For EME use many operators using the separate receiver antenna input to the receiver, or use another receiver anyway.  But the impact of the attenuator on receive mode is another factor to consider.

Other options include:

  • Modify the radio’s internal gain in the transmitter chain, preferably in the section amplifying at the transmitting frequency.  Depending on the design of the radio, there may be a point where the final mixer output is fed to the amplifier chain, which would be a good place to insert a suitable attenuator.
  • Insert a voltage on the ALC line, setting the gain of the transmitter to the highest it is allowed to be – reducing the output level to the highest it can be to safely drive the external amplifier.
  • Bypass amplifier stages.

Some types of mods would render the radio incapable of higher power output, so would need to be reversed when moving the radio on to another purpose. Whatever method is chosen, it must prevent the drive chain from producing enough power to drive the output stage to full power.

Importantly, it should be done in a way that is absolutely foolproof.  A casual mistake by the operator that destroys the external amplifier is something to prevent entirely.

The metering on the radio would be meaningless if some of these options were taken.  Separate methods of metering the drive level and adjusting for best operation would be required.

This is not a plug and play application. We are using a radio in a way that is outside its designed purpose.

The inability of the TS2000 (or other radio) to be used without modification for lower power purposes is no reflection of its suitability for other purposes. All commercial radios are built for the most common use by the majority of buyers. When we apply these general purpose radios to special uses such as for EME amplifier drivers, we cannot really be surprised that they are not ideal for EME drivers “out of the box”.

Wyong Field day and three SOTA activations

The Wyong field day is a major hamfest held at Wyong every February, with equipment exhibition and sales, a flea market for used equipment sales, a seminar room and supported by food and refreshments.

I have visited this event every year of the last 10 and have usually looked at the new equipment, passed through the flea market, sometimes buying something unique and desirable (such as the 3 element 6m yagi I bought one year)  but mostly just catching up with friends who I often see only at this event.  Some I never hear on the radio these days but they turn up at Wyong in February.

Having decided in advance to activate several summits on the way to Wyong, Andrew VK1AD (ex VK1NAM) and I set out from Yass at about 9am and reached the parking area in the vicinity of VK2/SY-002 Riley’s mountain at about 12:30, having stopped for coffee on the Hume Highway.

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Sign at the start of the walk up to Riley’s Mtn

The walk from the carpark to the summit was signposted as 2.6km each way or 5.2 km for the round trip.  The track through the forest was in good condition and the forest was green and healthy, with chirping birds the only sound breaking the peace apart from the noise of our boots on the gravel and dirt track.  After about 30-40 mins steady walk we found a sign pointing left labelled “Riley’s Lookout”.  Taking the side path we were soon standing high above the Nepean River enjoying the view of the forest and river.

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Nepean river and Blue Mtns National Park

Considering where to set up our radio gear to activate this rather nice location, we decided to walk the 50m or so back to the main track and set up there, using the sign as a support for the antenna pole.  In no time we had the antenna up in the air, the radio connected to the antenna and power and the microphone and key paddle plugged in.

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Equipment and operator at the lookout sign on Riley’s Mtn

We posted spots on SOTAWATCH  to be sure chasers and other activators looking out for S2S contacts knew we were on the air and where to find our signals.  A good session of contacts ensued with reasonable signals into Victoria, Queensland and South Australia, as well as some closer contacts in various parts of New South Wales.

One of the contacts made was with Marek OK1BIL/VK2 who was operating  at Mt Alexandra with Compton, VK2HRX.  We met Marek at Wyong the next day and had a good chat with him.

Leaving Riley’s mountain after about an hour of operation, we headed northwards to the Great Western Highway and then towards Sydney, onto the Newcastle freeway and eventually turned off the highway near Ourimba, to reach Mt Elliott VK2/HU-093.  Again this was a very pleasant and easy place to operate from, with picnic tables, expanses of grass inviting sevevral poles supporting antennas.  Here we used a 20m quarter wave vertical on one pole and a linked dipole on the other.  On 20m we made a few CW contacts into Europe and some into other parts of Australia.  Conditions were not good enough on 20m to make long distance SSB/voice contacts.

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One of the picnic tables at Mt Elliott was pressed into service as an operating desk
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Andrew VK1AD operating on 40m

Shortly before sundown we closed down and made our way to Wyong where we had booked accomodation for the night (two months earlier, or more).  We had a meal and some cool drinks at Panarotti’s at Tuggerah Westfield.

In the morning I woke early and decided to observe the International Space Station’s pass which was almost directly overhead.   I lost sight of it to the northeast when it was over New Caledonia according to the tracker.   It was brighter than most other things in the sky apart from the moon.

At the Field Day there was a good collection of second hand goods for sale in the flea market, some new items but it was strangely quiet in the corner where one of the larger traders usually is found.   At the VHF seminar, some discussion about the rules for VHF/UHF contests prompted me to make some unplanned comments about operating practices in these events, specifically about the practice of callinq CQ, making all contacts and listening all on 144.150, which many field and home stations appear to do.  A straw poll of those present revealed that while a number of people operated in that event, only a small number of them had made contacts into VK1, only 250km away from the Sydney area.  I suggested that this was due to being stuck on the calling frequency and it would help everyone to make more contacts, make more points in the contest and increase activity if they could move to other parts of the band during these events.  Let’s see whether a direct appeal to the operators has the desired effect.  I wish the contest rules did not specify a calling frequency.

We departed Wyong at about 12 noon and headed homeward. After a lunch break at Pheasants Nest we continued to the turnoff for Mt Wanganderry, VK2/IL-003.  Setting up there we were able to make contacts on 40m using SSB and CW, we did try 20m without any success.  This was a new summit for us both.

The antenna and shelter at Mt Wanganderry
The antenna and shelter at Mt Wanganderry
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Using the sun shelter at Mt Wanganderry

RD contest 2015

The exchange in the RD contest is a signal report in standard RS(T) format, followed by a 3 digit number indicating the number of years the operator has been licenced.  This year it was 50 for me so I thought that was a good excuse to operate in the RD.

I decided to use CW only and use the IC703 at 5 watts output.  This put me into the QRP/CW category.

The bands were ok for east coast contacts on 40m and 80m.  I didn’t hear any VK6 on CW which was unusual.  I did hear one on 20m but conditions were poor there and I was unable to make any contacts.

Total contact count was 100 on the RD logger screen but 99 in the summary – perhaps I confused it at some point when I backed out a contact that didn’t get completed.

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