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432MHz - an emerging band


#1

Having easily qualified SW-003 and SW-041 on 2m SSB last Saturday, I successfully repeated the exercise on 70cms SSB. As the interest in 432MHz appears to be on the increase with Frank G3RMD, Richard G4ERP and myself now active on a reasonably regular basis, it would be helpful to know just how many chasers have equipment and a reasonable antenna system. My list so far is G3RMD, G4ERP, G0LGS, M3SFN, 2E0IXC, G0RQL, G4BLH, G4OWG and G3CWI. G0UWK, G4UKP and G0RBD have also been logged. A crib sheet would be useful to ensure that the beam is pointed in the appropriate directions.

The advantage of 70cms is obvious - small antenna size. The downside is that in order to overcome the increased path loss the temptation is to increase the antenna size with the result that the beamwidth is reduced. Currently I run 25 watts to a 6 element DL6WU. It is an ideal add-on band, but I have plans to activate NW-001 and NW-008 using 70cms and 23cms only, so I hope there will be enough chasers for this. Please don’t make me use my 2m handheld.

73, Gerald


#2

In reply to G4OIG:

Hi Gerald, I have a 3ele logperiodic (DH3ZK) for 70cms, which when used with the ft857 (20w) seems a decent combination. If people know you are there, then they will hear you. Best so far was during a lift on Fair Snape Fell Christmas eve 2006 when I worked PA/ON lots of DL`s and in to SP. G4BLH worked in to DL on his handy on the same activation.

73 Steve.


#3

I intend doing some 70cm FM/SSB/CW activations once I get an antenna sorted out.

Tom


#4

No 70cm beam at present but with an 8x5/8 collinear and 50 watts on FM signals are often much better both ways on 70cms than they are on two metre FM so bring it on.

Only 20 watts on SSB but some more activity would give me an excuse to get a 70cms beam up.

Steve


#5

In reply to G4OIG:

I am all in favour of 70 cm activity, it was the first band I operated on (all hollow state, 1964, it seems a lifetime ago!) and I have retained an affection for it.

However. Make the most of it while you can.

Check the Ofcom website, “Spectrum Planning for the London 2012 Olympic Games” I think the title is. It will give you some nasty shocks!

73

Brian G8ADD


#6

70cms is a great band, however, I would be concerned that if it becomes popular for sota use, it might encourage more handheld/rubber duckers on the summits, with the accompanying poor signals.

73

Mike GW0DSP


#7

In reply to M1EYP:
Richard GW0VMW made a quadruple quad for 70cm a couple of years ago which is light and easy to pack in a rucksack. Performs very well too.

Details can be found here if anyone is interested

http://mw0idx.co.uk/quadruplequad.html

73
Roger MW0IDX


#8

In reply to MW0IDX:

Roger,

that looks interesting and I may give it a try.

Can you read the dimensions given in the table for the feed though - I can’t.

Keith.


#9

In reply to G8HXE:

Hi Keith,

Looks like -

      B       -       C      -      D

50MHz: 22.0 / 55.8 - 15 / 38.1 - 79 / 200.7

144MHz: 6.5 / 16.5 - 4.0 / 10.2 - 27 / 68.6

432MHz: 3.0 / 7.6 - 1.5 / 3.8 - 9.1 / 23.1

dims: inches / centimetres

Didn’t think you’d be interested in 220MHz!

73, Gerald


#10

In reply to G4OIG:
Another of the Cheltenham mafia has been QRV on 70cms for years… ;o)

73 Graham G4FUJ


#11

In reply to G4FUJ:

Another of the Cheltenham mafia has been QRV on 70cms for years…
;o)

I thought that was the case Graham, but I couldn’t find any QSOs in my logs, so I look forward to our first one in due course.

In reply to all:

Many thanks for your replies. I am actually considering running 70cms SSB before 2m SSB on a summit which may be a bit of a disappointment to some, but it would provide me with a gauge of how the band is shaping up activity wise. Is there a downside to this other than making the masses wait a few minutes?

73, Gerald


#12

In reply to G4OIG:

All this talk of 70cms activity fair makes my mouth water. I’m not sure how fruitful 70cms activity from GM would be although I’m sure those who covet 70cms contacts would love to have some more GM contacts in their logs. I do know that when we contest from DGL running 400W to a one or more big antennas we can call for a long time and work nobody. The fact that we often work distances in excess of 1000kms means that we have a potent signal. It can be most annoying to work into HB9 on 70cms and yet struggle to work 100 to 200kms into NW England.

I have some issues with my HF setup I want to resolve first (particularly 80m) but I’m interested in trying 70cms from my GM activations if I know that people in theoretical range are prepared to listen for me. Perhaps the key is ensuring that people will be pointing North at the right time?

Andy
MM0FMF


#13

In reply to MM0FMF:

Hi Andy,

Alerting the activation in advance is certainly important. Another key factor is to consider the ability of the summit to produce results and choose accordingly. I would hope that a number of GM chasers would have equipment for the band.

I managed QSOs with Frank G3RMD and Don G0RQL from SS-245 in Galloway last October and regretted not having taken the antenna up SS-170 in the morning. I will certainly have it on board for my next GM trip - currently considering where to go. I will email you so we can meet up again, in the pub if not on an actual summit.

73, Gerald

P.S. I have managed to work GM4HAM/P from single point summits in Mid and South Wales. It is worth having the band on board if activations coincide with 70cms contests.


#14

“Perhaps the key is ensuring that people will be pointing North at the right time?”

Where do I get one of these highly magnetic CW paddles?

Tom


#15

In reply to G4OIG:

I managed QSOs with Frank G3RMD and Don G0RQL from SS-245 in Galloway
last October

Interesting. I certainly agree that in the case of GM, some summits will be more favourable than others and activating when there is a 70cms contest on will help immeasurably. In addition to that, I’m sure it’ll be possible to arrange 70cms activity weekends when we can try to get a number of stations QRV for S2S contacts at the same time.

Now all that’s needed at this end is a lightweight and effective antenna and something to boost the 5W from the 817. The quadruple quad mentioned earlier looks worthy of further investigation as I dont fancy carrying either my 19ele or 21 ele Tonnas with me. And what’s this here on the shelf, why it’s a MM 70cms TV TX with, if I read the PCB label correctly a linear PA producing 20W for 1W of drive. Dump the TV modulator and add some relays and I could be in business!

Andy
MM0FMF

Edit:
A quick check shows at least 12W out without any modulation. Looks like the basis of a nice cheap PA. Does anyone have a circuit diagram? Model number is Microwave Modules TVT432.


#16

In reply to MM0FMF:

Hi Andy,

I think you’ll be surprised what 5W can do with a moderate amount of gain from the antenna. I used that amount of power from SW-032, SW-028 and SW-036 and worked Frank and Don using the 6 element yagi. I also managed to contact Frank from SW-039 at that power (Don was busy elsewhere). On SW-031 I worked them both and also Richard G3CWI on LD-026 for an S2S, but I was using 25W out on that summit. I run the higher power purely in the hope of offering the summit to more chasers - that’s my philosophy for 2m as well. The 70cms linear is now a permanent part of my SOTA kit.

I like the idea of a 70cms activity weekend. There are also the 70cms activity contest evenings later in the year when it becomes a pleasure to sit out on a summit.

73, Gerald


#17

In reply to G4OIG:

Well now we’re cooking with gas.

I disconnected the TV modulator from the PA and connected a short length of RG316 to the PA input and terminated that in a BNC socket. Then I connected the 817 to this and put it on 432.200 USB and connected a power meter and dummy load. Apply power, press PTT on mike and hope. No smoke, no oscillations. A few shouts of waaaaaalo waaaaaaaaalo into the mike and there’s a good 15W with the PA fed at 12V and the 817 on its internal cells. Up the voltage to 13.8 and the power is nearer 17/18W. Result!

Andy
MM0FMF


#18

In reply to MM0FMF:

Excellent news! Guess I had better have an attenuator to hand when I come up to GM!

73, Gerald


#19

In reply to G4OIG:

Hi Gerald,

‘There are also the 70cms activity contest evenings later in the year when it becomes a pleasure to sit out on a summit.’

I have a go at these during the year from a non-SOTA site but try to operate from NW-051 during the lighter evenings. Last year on the 12th June I had 20 contacts between 20:00 and 21:30BST using 5W and a 7ele ZL Special. Best dx was G5LK at 281km and also worked EI3GE. Went again on the 10th July and had 15 contacts. As you know these activity contests are on the second Tuesday of the month throughout the year between 8pm and 10:30pm local time.

There is also a low power contest (<25W) held on the morning of the first Sunday in August and this always generates a lot of activity. In last year’s event I ran 20W to a 19ele Yagi and had 35 contacts.

Look forward to working you on this band!

73, Ron


#20

In reply to GW4EVX:

Hi Ron,

I am looking at activating some summits on Tuesday evenings if we have SOTA activity periods again this year. I might well make one or two of those the second Tuesday and run in the 70cms contest. The problem is that to do this I would need to take the afternoon off work and be prepared to get home well after midnight as there are more rocking horse droppings around here than SOTA summits.

My best performance from a SOTA summit in contest hours is 12 in 50 minutes using 25 watts to my little 6 element - best distance 316km. Not as far as the QSO with Don G0RQL from GM last October, but that was partly sea path.

As you say, looking forward to having a QSO. I’ll add you to the growing list! I seem to recall John M0JDK is QRV from his home QTH as well.

73, Gerald