Sound good to me Quentin. If its anything like ZL they will have spectrum guards bands and by nestling a couple of megs down we should be OK. We don't transmit that much and all narrow band emissions.
Cheers, Steve
The 3.4 GHz amateur band - it's future ?
Re: The 3.4 GHz amateur band - it's future ?
Greetings to all again!
I acknowledge that, on this 'Forum', several folk have recently 'voted' for a move to 3398 MHz. At the end of the day, I don't have a personal preference for one of 3395 MHz or 3398 MHz over the other.
Before I get onto my main point, and whilst I don't use a KUHNE transverter, a local amateur, Kevin VK4WA, has learned directly from the Kuhne Company that both of those frequencies can still be reached by an unmodified KUHNE 3400 MHz to 144 MHz transverter by way of lowering the IF frequency less than 144 MHz. But he was advised that lowering the IF by 5 MHz with 139 MHz representing 3395 MHz is about the limit of what's possible in this way. Just how many folk around Australia and New Zealand have these particular transverters is not known, but there are two that I know of in South East Queensland.
However, whilst 3398 MHz seems to be a convenient frequency to which to go (and that was what some Brisbane VHF Group fellows agreed on early in the piece), I must draw readers' attention to the postings last week by Rod VK4VU. He was describing the out-of-band emissions mandated by ACMA for base stations used for the provision of NBN 3.4 GHz wireless internet services. Whilst it’s possible that the out-of-band emissions may actually be better than those mandated, this can’t be guaranteed.
Also - we shouldn’t forget that the customer terminals (albeit lower power than the base stations) will also be operating in the same channel (TDD). Emission mask for these devices is also specified in the ACMA MS39 document.
Reconsidering Rod's argument/information, if a radio amateur (home or portable) was located near an area using the lowest available 'channel', it follows that we would do well to be operating as far away from 3400 MHz as possible. And Rod's private suggestion to me, based on some knowledge of the technologies involved, is that more than 5 MHz separation may be even better.....
To put this in perspective, at 2 MHz separation, the ACMA mask calls for an emission level of 7.2 dBm measured in 100 kHz, which converts to -7.4 dBm in a 3 kHz bandwidth (which we radio amateurs typically use). A reasonably good 3.4 GHz SSB receiver will have a noise floor of around -137 dBm (2 dB NF/3 kHz bandwidth), and let’s assume we are using a loop yagi or a small dish antenna with say 20 dBi gain. Let’s say the base station is 10 km away and is line of sight to the amateur station. Path loss is therefore around -123 dB. The worst case “interference” level will therefore be -7.4 -123 + 20 = -110.4 dBm, which going to be around 26 dB above the receiver noise floor.
Based on the ACMA mask, the mask level at 5 MHz offset will be -12.2 dBm/3 kHz, so the interference will be around 5 dB lower than it was at 2 MHz offset. Moving to a 10 MHz offset, the mask is now at -23 dBm/3 kHz, the interference is 10 dB lower again – so its 15 dB lower than it was at 2 MHz offset.
It’s really a bit of a lottery. What is the probability that you’ll have an NBN base station located near your location, and it’s operating on Channel 1, and just happens to be on bore-site towards your favourite DX station?
Any potential interference could be mitigated by:
a) relocating away from the base station site;
b) ensuring that you have narrow beamwidth antennas and low side –lobes; and/or
c) operating on a frequency further away from Channel 1 (Refer MS39 Figure 1).
I urge all folk reading this to seriously consider whether 2 MHz separation is enough. It would seem that there are advantages in establishing a guard band greater than the currently proposed value of 2 MHz. Whether moving to 3395 MHz or even lower in the band is adequate separation remains to be seen!
And back to the subject of the Kuhne transverters, Rod has commented to me: "It's clear that 3395 is at least 5 dB better than 3398. Then again 3390 is 15 dB better than 3398, but moving Kuhne transverters more than 5 MHz needs a factory re-tune. A better solution would be to use a ZLPLL as the LO source (in the 100 MHz region) and tweak the LO if needed. That would probably be cheaper than sending the transverter back to Germany for a reprogramming of the PLLVCXO.
"It all depends on how likely you'll have an NBN transmitter in the neighbourhood, and how likely it is that you beam directly at it. Hopefully they'll be a little less ubiquitous than the 2.4 GHz WLAN devices that are around."
Well, fellows, see what you think now.....and remember that we don't have to 'move' immediately - there seems to be enough time to consider what's best for all of us.
Very best wishes,
--Doug Friend, VK4OE.
I acknowledge that, on this 'Forum', several folk have recently 'voted' for a move to 3398 MHz. At the end of the day, I don't have a personal preference for one of 3395 MHz or 3398 MHz over the other.
Before I get onto my main point, and whilst I don't use a KUHNE transverter, a local amateur, Kevin VK4WA, has learned directly from the Kuhne Company that both of those frequencies can still be reached by an unmodified KUHNE 3400 MHz to 144 MHz transverter by way of lowering the IF frequency less than 144 MHz. But he was advised that lowering the IF by 5 MHz with 139 MHz representing 3395 MHz is about the limit of what's possible in this way. Just how many folk around Australia and New Zealand have these particular transverters is not known, but there are two that I know of in South East Queensland.
However, whilst 3398 MHz seems to be a convenient frequency to which to go (and that was what some Brisbane VHF Group fellows agreed on early in the piece), I must draw readers' attention to the postings last week by Rod VK4VU. He was describing the out-of-band emissions mandated by ACMA for base stations used for the provision of NBN 3.4 GHz wireless internet services. Whilst it’s possible that the out-of-band emissions may actually be better than those mandated, this can’t be guaranteed.
Also - we shouldn’t forget that the customer terminals (albeit lower power than the base stations) will also be operating in the same channel (TDD). Emission mask for these devices is also specified in the ACMA MS39 document.
Reconsidering Rod's argument/information, if a radio amateur (home or portable) was located near an area using the lowest available 'channel', it follows that we would do well to be operating as far away from 3400 MHz as possible. And Rod's private suggestion to me, based on some knowledge of the technologies involved, is that more than 5 MHz separation may be even better.....
To put this in perspective, at 2 MHz separation, the ACMA mask calls for an emission level of 7.2 dBm measured in 100 kHz, which converts to -7.4 dBm in a 3 kHz bandwidth (which we radio amateurs typically use). A reasonably good 3.4 GHz SSB receiver will have a noise floor of around -137 dBm (2 dB NF/3 kHz bandwidth), and let’s assume we are using a loop yagi or a small dish antenna with say 20 dBi gain. Let’s say the base station is 10 km away and is line of sight to the amateur station. Path loss is therefore around -123 dB. The worst case “interference” level will therefore be -7.4 -123 + 20 = -110.4 dBm, which going to be around 26 dB above the receiver noise floor.
Based on the ACMA mask, the mask level at 5 MHz offset will be -12.2 dBm/3 kHz, so the interference will be around 5 dB lower than it was at 2 MHz offset. Moving to a 10 MHz offset, the mask is now at -23 dBm/3 kHz, the interference is 10 dB lower again – so its 15 dB lower than it was at 2 MHz offset.
It’s really a bit of a lottery. What is the probability that you’ll have an NBN base station located near your location, and it’s operating on Channel 1, and just happens to be on bore-site towards your favourite DX station?
Any potential interference could be mitigated by:
a) relocating away from the base station site;
b) ensuring that you have narrow beamwidth antennas and low side –lobes; and/or
c) operating on a frequency further away from Channel 1 (Refer MS39 Figure 1).
I urge all folk reading this to seriously consider whether 2 MHz separation is enough. It would seem that there are advantages in establishing a guard band greater than the currently proposed value of 2 MHz. Whether moving to 3395 MHz or even lower in the band is adequate separation remains to be seen!
And back to the subject of the Kuhne transverters, Rod has commented to me: "It's clear that 3395 is at least 5 dB better than 3398. Then again 3390 is 15 dB better than 3398, but moving Kuhne transverters more than 5 MHz needs a factory re-tune. A better solution would be to use a ZLPLL as the LO source (in the 100 MHz region) and tweak the LO if needed. That would probably be cheaper than sending the transverter back to Germany for a reprogramming of the PLLVCXO.
"It all depends on how likely you'll have an NBN transmitter in the neighbourhood, and how likely it is that you beam directly at it. Hopefully they'll be a little less ubiquitous than the 2.4 GHz WLAN devices that are around."
Well, fellows, see what you think now.....and remember that we don't have to 'move' immediately - there seems to be enough time to consider what's best for all of us.
Very best wishes,
--Doug Friend, VK4OE.
Re: The 3.4 GHz amateur band - it's future ?
From the September edition of AR, it seems that (for now), the target is that operation will take place on 3398.xxx MHz.
It seems that people with the likes of the Kuhne transverters have a problem when used with FT817s as IF transceivers as they won’t go down to 142.xxx easily – in lieu of 144.xxx MHz.
These Kuhne devices allow the use of a 10.00000 MHz external reference signal but what if it isn’t actually on-frequency ? The transverter is then shifted off 3400.xxx, correct ? We all know that LO frequency injection errors cause everyone’s interpretation of frequency to be in question – just take a sample during a VHF/UHF Field day.
Now what if we intentionally shift it off 10.000 down to say 9.98464373 or 9.99385749 MHz then it will, respectively, shift from 3400.xxx to 3395.xxx or 3398.xxx MHz.
The maths:
Tx/Rx band : 3400.000
IF band : 144.000
Therefore LO is at 3256.000
We now want the LO to be at 3254.000 for a 2MHz downshift or 3251.000 for a 5MHz downshift.
The divisor and reference frequencies within the Kuhne are preset but if we reduce the reference frequency by a percentage then that doesn’t matter….
So for a 2MHz shift, we have 3254/3256 * 10.0000 = 9.993857493857493857 MHz
It just so happens that this frequency can be generated in a PLL from a 10.000MHz reference using a N divider value of 1627 and a Ref divider of 1628.
So for a 5MHz shift, we have 3251/3256 * 10.0000 = 9.984643734643734643 MHz
It just so happens that this frequency can be generated in a PLL from a 10.000MHz reference using a N divider value of 2601 and a Ref divider of 2605.
I might add that these are the only divisor sets possible for an exact 10.000 reference signal eg GPSDO or other standard.
That means two possibilities : use a PLL at approx 10MHz to generate one or the other of these two reference frequencies (eg switchable); or generate them using DDS techniques.
How you create your “actual box’ is up to you but all you need do is unplug the reference 10MHz feed from your 3.4GHz sync port, place the new reference-generating box in line and, voila, you are now on 3395.xxx or 3398.xxx MHz.
Now you don’t really need to worry if the transition to 3398 is just temporary – if it isn’t then just "flick the switch".
Just a quick google produced this project - just need to set it up for an external 10MHz reference : http://alternatezone.com/electronics/dds.htm although it may need a buffer amp as the level required for the Kuhne devices is closer to +10dBm than 0dBm. The kit may no longer be available but the idea/schematic is there.
73 Doug
It seems that people with the likes of the Kuhne transverters have a problem when used with FT817s as IF transceivers as they won’t go down to 142.xxx easily – in lieu of 144.xxx MHz.
These Kuhne devices allow the use of a 10.00000 MHz external reference signal but what if it isn’t actually on-frequency ? The transverter is then shifted off 3400.xxx, correct ? We all know that LO frequency injection errors cause everyone’s interpretation of frequency to be in question – just take a sample during a VHF/UHF Field day.
Now what if we intentionally shift it off 10.000 down to say 9.98464373 or 9.99385749 MHz then it will, respectively, shift from 3400.xxx to 3395.xxx or 3398.xxx MHz.
The maths:
Tx/Rx band : 3400.000
IF band : 144.000
Therefore LO is at 3256.000
We now want the LO to be at 3254.000 for a 2MHz downshift or 3251.000 for a 5MHz downshift.
The divisor and reference frequencies within the Kuhne are preset but if we reduce the reference frequency by a percentage then that doesn’t matter….
So for a 2MHz shift, we have 3254/3256 * 10.0000 = 9.993857493857493857 MHz
It just so happens that this frequency can be generated in a PLL from a 10.000MHz reference using a N divider value of 1627 and a Ref divider of 1628.
So for a 5MHz shift, we have 3251/3256 * 10.0000 = 9.984643734643734643 MHz
It just so happens that this frequency can be generated in a PLL from a 10.000MHz reference using a N divider value of 2601 and a Ref divider of 2605.
I might add that these are the only divisor sets possible for an exact 10.000 reference signal eg GPSDO or other standard.
That means two possibilities : use a PLL at approx 10MHz to generate one or the other of these two reference frequencies (eg switchable); or generate them using DDS techniques.
How you create your “actual box’ is up to you but all you need do is unplug the reference 10MHz feed from your 3.4GHz sync port, place the new reference-generating box in line and, voila, you are now on 3395.xxx or 3398.xxx MHz.
Now you don’t really need to worry if the transition to 3398 is just temporary – if it isn’t then just "flick the switch".
Just a quick google produced this project - just need to set it up for an external 10MHz reference : http://alternatezone.com/electronics/dds.htm although it may need a buffer amp as the level required for the Kuhne devices is closer to +10dBm than 0dBm. The kit may no longer be available but the idea/schematic is there.
73 Doug
Doug VK4ADC, QG62lg51
http://www.vk4adc.com
http://www.vk4adc.com
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Re: The 3.4 GHz amateur band - it's future ?
It's simply a matter of resoldering some links on the front panel PCB as described in a link in my posting a bit earlier in this thread.VK4ADC wrote:... FT817s ... won’t go down to 142.xxx easily.
For some who might think doing this is a no-no, please refer to the WIA web site: http://www.wia.org.au/newsevents/news/2 ... /index.php
Having a radio that is capable of out-of-band operation is NOT illegal, but using it on-air and out-of-band certainly IS illegal. Here it is being used as an IF, so no problem.
As I'm sure you're aware, a DDS most likely won't give an exact frequency. I haven't done the maths, but it will probably be quite close - a couple of Hz at 3.4 GHz.VK4ADC wrote:... or generate them using DDS techniques.
I've done a similar thing. A commercial radio being used for a beacon used a 12 MHz reference. It could be programmed in 5 kHz steps, but the beacon frequency ended with a 4. So, to move it down that little bit, I generated an 11.999... MHz reference from a 10 MHz reference using a DDS.
eBay has cheap DDS boards. I used a AD9851 board because that chip has an onboard x6 clock multiplier e.g. http://www.ebay.com.au/itm/381248883052
The clock needs to be more than twice the output frequency so with the multiplier and a 10 MHz, clock, it could generate up to 25 MHz.
The onboard filters may need to be fiddled as they are designed for a 180 MHz clock.
It also needs a microprocessor of some sort to program it up. A little Arduino board fits the bill nicely. e.g. http://www.ebay.com.au/itm/271966090648
Regards,
Dave
VK3HZ
Re: The 3.4 GHz amateur band - it's future ?
My DB6NT Kuhne based system with a 144 MHz IF might only require using 142MHz as the IF or modifications the Kuhne unit itself.
Has anyone tried driving these transverters at 142 MHz?
In the field I use an FT817 as the IF radio. There is a good chance that this rig will be capable, with a little help to make the QSY down to 142.00 MHz. There are lots of postings and descriptions on the web for extended transmit with this radio. Has anyone actually done this?
There also appears to be different suggestions for the FT817 and the FT817NDmodels.
So again = has anyone successfully actually done this mod?
Kevin VK4UH
Brisbane
Kevin (KJ) VK4UH
Brisbane
Brisbane
Re: The 3.4 GHz amateur band - it's future ?
Kevin.
I have not tried working the Kuhne module at 2Mhz down myself but I did contact Kuhne directly via email about this and they did the experiment in the factory and said there is no problems with the 144 IF module working at 142Mhz IF and there are no losses in signal or any problems with Freq accuracy so this should be a winner for all those who have Kuhne products on 3.4Ghz. I did pass this info onto Doug VK4OE so not sure why he has not passed this on to other people yet.
Cheers
Robert
VK4LHD
I have not tried working the Kuhne module at 2Mhz down myself but I did contact Kuhne directly via email about this and they did the experiment in the factory and said there is no problems with the 144 IF module working at 142Mhz IF and there are no losses in signal or any problems with Freq accuracy so this should be a winner for all those who have Kuhne products on 3.4Ghz. I did pass this info onto Doug VK4OE so not sure why he has not passed this on to other people yet.
Cheers
Robert
VK4LHD
Re: The 3.4 GHz amateur band - it's future ?
Hi Kevin
re the FT817 mod - it does work. I have my units modified to use 420Mhz which I use as my IF for the transverters. I also recently suggested this mod to Alan VK3XPD to help solve an issue he had and it also worked for him. A bit of care is required and you can quite easily damage the front panel electronics if your smd soldering techniques aren't that great.
Rex
re the FT817 mod - it does work. I have my units modified to use 420Mhz which I use as my IF for the transverters. I also recently suggested this mod to Alan VK3XPD to help solve an issue he had and it also worked for him. A bit of care is required and you can quite easily damage the front panel electronics if your smd soldering techniques aren't that great.
Rex
Re: The 3.4 GHz amateur band - it's future ?
Thanks for all the responses to my earlier enquiry about extending 2m TX of the FT817 IF transceiver.
The mod' has been completed successfully here to allow 142MHz drive of the Kuhn 3.4GHz transverter and allow operation on the new 3398GHz activity frequencies
My thanks to Rex VK4REX for his skill and bench to achieve that.
Kevin VK4UH
The mod' has been completed successfully here to allow 142MHz drive of the Kuhn 3.4GHz transverter and allow operation on the new 3398GHz activity frequencies
My thanks to Rex VK4REX for his skill and bench to achieve that.
Kevin VK4UH
Kevin (KJ) VK4UH
Brisbane
Brisbane
Re: The 3.4 GHz amateur band - it's future ?
Greetings to all readers.
Yesterday, prompted by the on-going conversation regarding the apparently imminent need to move from 3400 MHz to 3398 MHz, at least in areas around our major cities, I got out my two (home brew) transverters for the band and did comparative tests of power out and minimum discernable signal at the two frequencies. For both transverters the IF radio is on the 70 cm. band somewhere away from the calling frequency so, in each case, all I had to do was move the IF radio down by 2 MHz, a very easy thing to do.
I'm pleased to report, and as one would anticipate with such a relatively small shift in operating frequency, that for each transverter there was hardly any noticeable difference between the two frequencies. And for one of them the same signal that was minimally discernable at 3400 MHz was just a little easier to copy 2 MHz down the band as shown on the IF radio! I've also changed the labels on my two transverters to make them look like 3398 MHz units!
So, the short story is that for most other folk as well, moving two megahertz is unlikely to be a problem for the TX and RX electronics operating at 3398 MHz. Now I can confidently come up on 3398 MHz, whilst I can still operate on 3400 MHz as well, should the need arise.
--Doug, VK4OE.
Yesterday, prompted by the on-going conversation regarding the apparently imminent need to move from 3400 MHz to 3398 MHz, at least in areas around our major cities, I got out my two (home brew) transverters for the band and did comparative tests of power out and minimum discernable signal at the two frequencies. For both transverters the IF radio is on the 70 cm. band somewhere away from the calling frequency so, in each case, all I had to do was move the IF radio down by 2 MHz, a very easy thing to do.
I'm pleased to report, and as one would anticipate with such a relatively small shift in operating frequency, that for each transverter there was hardly any noticeable difference between the two frequencies. And for one of them the same signal that was minimally discernable at 3400 MHz was just a little easier to copy 2 MHz down the band as shown on the IF radio! I've also changed the labels on my two transverters to make them look like 3398 MHz units!
So, the short story is that for most other folk as well, moving two megahertz is unlikely to be a problem for the TX and RX electronics operating at 3398 MHz. Now I can confidently come up on 3398 MHz, whilst I can still operate on 3400 MHz as well, should the need arise.
--Doug, VK4OE.
Re: The 3.4 GHz amateur band - it's future ?
Time to get out of Dodge...
A whole lot of PTS - PMTS Class B Licences were issued on 29th April and our club has received a letter from NBN Co. advising that we need to turn off the VK5RLZ beacon on 3400.452MHz (we'll actually move it to 3398.452MHz).
A whole lot of PTS - PMTS Class B Licences were issued on 29th April and our club has received a letter from NBN Co. advising that we need to turn off the VK5RLZ beacon on 3400.452MHz (we'll actually move it to 3398.452MHz).
73
Iain Crawford - VK5ZD
Munno Para West, SA - PF95ih
Iain Crawford - VK5ZD
Munno Para West, SA - PF95ih
Re: The 3.4 GHz amateur band - it's future ?
New NBN Co licenses are being issued on an almost daily basis now.VK5ZD wrote:Time to get out of Dodge...
A whole lot of PTS - PMTS Class B Licences were issued on 29th April and our club has received a letter from NBN Co. advising that we need to turn off the VK5RLZ beacon on 3400.452MHz (we'll actually move it to 3398.452MHz).
Even licenses granted today - May 5 - are showing up on the database.
Adam, Brisbane
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Re: The 3.4 GHz amateur band - it's future ?
It's going to be interesting in the Sunshine Coast Hinterland. Just did a search and virtually no licenses have been issued.
The local council (Sunshine Coast Regional council) has rejected most of the NBN's site proposals for this area based on amenity issues. 18 sites that I am aware of so far and there is massive community rejection of the proposals.
NBN Co have been found to be sparse with the truth when dealing the local communities which has further angered the community.
I found Ian's (VK5ZD) comment interesting that NBN Co were telling them to turn off the beacon, I would have thought that was the responsibility of ACMA, the licensing authority - NBN is just another customer.
Rex
The local council (Sunshine Coast Regional council) has rejected most of the NBN's site proposals for this area based on amenity issues. 18 sites that I am aware of so far and there is massive community rejection of the proposals.
NBN Co have been found to be sparse with the truth when dealing the local communities which has further angered the community.
I found Ian's (VK5ZD) comment interesting that NBN Co were telling them to turn off the beacon, I would have thought that was the responsibility of ACMA, the licensing authority - NBN is just another customer.
Rex