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5MHz NOV changes consultation


#1

For UK readers…

There will be a chance for 5MHz users in the UK to comment on proposals made by OFCOM on behalf on the primary user (MOD).

To precis this, what is on offer is more bandwidth in several disjoint chunks in exchange for a different power limit and a maximum antenna height of 5m AGL.

The changes to power and antennas is unlikely to affect any activators in the UK using 5MHz but may impact on the chasers, especially those with good antennas.

See http://www.rsgb.org/consultations/new-five-mhz-nov-proposals.php

Andy
MM0FMF


#2

In reply to MM0FMF:

Crikey! What a hodge-podge of channels and bands - it would be difficult putting that into memories, and using the VFO makes an accidental slip into one of the gaps quite possible…but its better than what we have so I hope it is grabbed with both hands!

73

Brian G8ADD


#3

In reply to G8ADD:

Crikey! What a hodge-podge of channels and bands - it would be
difficult putting that into memories, and using the VFO makes an
accidental slip into one of the gaps quite possible…but its better
than what we have so I hope it is grabbed with both hands!

Indeed! I had been hoping for one single continuous chunk of spectrum, even if it was only 100 kHz. However, I agree that any increase in the allocation is better than nothing at all - and we are at the mercy of the primary user. I do not see the need for AM at 5 MHz. This is an obsolete mode, very uneconomical in its use of spectrum space.

Also, I do not favour the proposed 5m height restriction for antennas, and I see no need to change the already generous power limit! (How do you calculate the ERP when using a random wire draped over tree branches?)

73,
Walt (G3NYY)


#4

In reply to G3NYY:

Also, I do not favour the proposed 5m height restriction for antennas,

Yes, I can see that one being a problem. I’m pretty sure my SOTA inverted-V has its apex a couple of metres higher than the proposed maximum.

73, Rick M0LEP


#5

I do not want these Antenna Height restrictions either (but something a little less restrictive would perhaps be fine).

My existing Antenna feed point at Chimney height is almost certainly above 5m and I really do not have room to fit something else for 60m into my postage stamp garden.

Stewart G0LGS


#6

In reply to MM0FMF:

Looking more closely, I find myself wondering which genius came up with the idea of sharing FE with AM? FE is the de facto calling frequency and in practice the preferred frequency for SOTA and its various spin-offs. An incursion of AM there is bound to cause conflict - I have no axe to grind against AM, it deserves a place, but not there!

Whilst it is unlikely to affect me, I am concerned that the idea of EIRP has raised its head - surely it is an unmeasurable fiction?

73

Brian G8ADD


#7

In reply to G8ADD:

It is one of the points raised elsewhere. The argument being if you wish people to comply then it should be something that is straightforward and easy for them to comply with. The thinking in the same place is that the MOD want to ensure we don’t use the band for DXing hence the antenna height limits.

So what comes next is “if you want the antennas up higher you will need to use less power”. Perhaps we should ask “how high can we have it with a 100W power limit?”

AM? I agree Brian. it deserves a place. How does “in the history books” sound? :wink:

Andy
MM0FMF


#8

In reply to MM0FMF:

AM? I agree Brian. it deserves a place. How does “in the history
books” sound? :wink:

Unkind! I’m not a fan of AM today, but it is the mode I started with nearly 50 years ago, I remember it with affection, and those who wish to conserve the mode and the old rigs that used it have my sympathy…though I think that drifty, chirpy rigs like the 19 set or the T1154 should be tamed before being let loose on modern bands!

73

Brian G8ADD


#9

In reply to G8ADD:

My thoughts also Brian. It’s also a lot easier to build an AM/DSB rig than one of these new fangled SSB ones.

Rick.


#10

In reply to MM0FMF:

The thinking in the same place is that the MOD want to ensure we don’t use the band for DXing hence the antenna height limits.

So why the bit about harmonising with other administrations? Basically it adds up to “you can have the same frequency as amateur operators in other countries, but we don’t want you to work them”

Strikes me the same team are working on this as on the Government’s health bill - there is a lack of joined-up thinking. Why have we adopted a culture of change for the sake of change? Is the band really broken and not working? I’d rather have a few more 3kHz channels if we can’t have a decent continuous allocation. At least that way we wouldn’t be likely to stray into an unauthorised part of the frequency spectrum.

Overall I am thoroughly disappointed.

Gerald G4OIG


#11

I see that the Forum is now (just) live.

(I have already posted a response).


#12

In reply to M0RCP:

My thoughts also Brian. It’s also a lot easier to build an AM/DSB rig
than one of these new fangled SSB ones.

It’s even easier to build a spark transmitter, but there are not many of them around these days!

73,
Walt (G3NYY)


#13

In reply to G3NYY:
At a rough guess I would say that there are far more AM and DSB rigs about than there are spark transmitters! AM and DSB may be more complex but they are also legal.

73

Brian G8ADD


#14

In reply to G8ADD:

In reply to G3NYY:
At a rough guess I would say that there are far more AM and DSB rigs
about than there are spark transmitters! AM and DSB may be more
complex but they are also legal.

Come on now Brian, think of the nostalgia (and interference)
it would generate if you were to drag that rotary spark set
and coherer up Walton Hill on Friday.

73 Dave


#15

In reply to G0ELJ:

Come on now Brian, think of the nostalgia (and interference)
it would generate if you were to drag that rotary spark set
and coherer up Walton Hill on Friday.

I’m sure Brian is quite accustomed to packing a couple of Leyden jars in his rucksack!

:wink:

73,
Walt (G3NYY)


#16

In reply to G3NYY:


Like this Walt.
73 Geoff


#17

In reply to G6MZX:

In reply to G3NYY:
http://www.youtube.com/watch?v=Zilvl9tS0Og
Like this Walt.

Tee hee! We had a working Wimshurst machine at school. Also a Van de Graaff generator.
You could get nice shocks off both of them! (Probably outlawed by Elfin Safety nowadays.)

:slight_smile:

73,
Walt (G3NYY)


#18

In reply to G3NYY:

In reply to G6MZX:

In reply to G3NYY:
http://www.youtube.com/watch?v=Zilvl9tS0Og
Like this Walt.

Tee hee! We had a working Wimshurst machine at school. Also a Van de
Graaff generator.

LOL, we had one at skool too, Walt. It was housed in a dark wood and glass case.

You could get nice shocks off both of them! (Probably outlawed by
Elfin Safety nowadays.)

Kids are not allowed to play conkers at skool without wearing a suit of armour, goggles and of course, an ambulance and RAYNET in attendance :wink:

73 Mike
2E0YYY


#19

In reply to MM0FMF:

In reply to a few posters, I am sure a spark transmitter couldn’t be worse than living next door to someone with a PLT/PLA device, or numerous other things that cause horrendous QRM for users of shortwave. The only difference is that a spark transmitter is (Very) wideband.

Back to the original subject, I have looked at the proposal from the MOD & like many others am concerned by the 5m max antenna height requirement.

I have always given the height of my 80m wire loop as 6m AGL, but today for an unrelated reason I decided to actually measure it. While what could be described as it’s feedpoint in the attic above my head, is indeed around 6m AGL, the antenna wire leaves the building at gutter level which is only 5.4m / 6m AGL depending on which side of the house I measure. From this, it appears that the majority of my antenna is only about 4.5m AGL, which is much lower than I would have thought.

Overall, still over the 5m height limit though.

The 200 Watts EIRP limit would not seriously affect most UK amateurs as most of us only run 100 Watts maximum into nothing more than a dipole. As the gain of a dipole (according to Wikipedia as my memory is a bit slow)is given as 2.15dBi,you would still be fine running your 100 Watt radio into a simple dipole.

I am sure the MOD do not want the band to be used for DX working, which I tend to agree with, as the band is far too useful to become another 40m, which at present exhibits similar NVIS properties. However, as some respondents to the
Litmus test have already said, the 5m height limit would automatically prevent use by stations with antennas located on tall buildings, or even over the ridge of a normal house. This would be a problem when assisting the relevant services during any emergency / disaster situation.

The offer of additional spectrum is to be welcomed, & the widening of FE to allow AM use suggests that the MOD themselves are becoming more flexible with other services using their portions of the MF/HF spectrum, but of course this does mean that there is more pressure on the UHF/SHF amateur allocations.

I have yet to respond to the Litmus test myself, but I will certainly be putting my views forward as I feel this is a very important part of the spectrum that we as amateurs can, and are, making very good use of.

Any changes should take into account that most of us live in houses, with neighbours, & limited space for multiple antennas. In some cases not even room for one!

The above views are my own, & do not represent SOTA in any way.

Apologies for any errors,

Best 73,

Mark G0VOF


#20

In reply to G0VOF:

The 200 Watts EIRP limit would not seriously affect most UK amateurs

The main complaint seems to be that it’s trickier to measure half-way accurately…

the 5m height limit would automatically prevent use by stations with antennas
located on tall buildings, or even over the ridge of a normal house.

…and rules out the use of a vertical (unless it’s pretty severely loaded) such as might be found being used by someone with severely restricted antenna space.

My current SOTA inverted-V has its apex at about 7 metres, so it’d be out of the running if the 5 metre height restriction gets through. Stringing an inverted-V with its apex at 5 metres would, I guess, require a bit more sideways tension, or some extra supports part-way along. Interesting to try, perhaps…

73, Rick M0LEP