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First Dabble at HF Fails


#1

First the kit : inverted V doublet, radiator lengths 9.8 metres, fed via 4 metres of 300 ohm slotted twin feeder, centre height 5 metres. Rig FT817 via a antenna match (QRP ATU, RADCOM, May 2003). This set-up might eventually be useable on several bands by adjusting the matching unit.

Initial check with an MFJ antenna tester showed the antenna can be matched to 50 ohms at 80M and at 40M

Operated from Long Mountain - Beacon Ring (GQ/MW-026), and started calling CQ on 3.750 at 12:00 UTC as alerted. No replies after 15 minutes of calling, but did get one QSO with G3XJP (N Herefordshire)by tailending. This at least showed that my signals were getting out. Another fruitless 10 minutes of calling CQ on 3.750 before I went up to 40M. Able to get a QSO with GB2CAT (Scarborough) and found a space at 7.079, calling CQ to no effect for another 15 minutes. A call to Don, G0NES (Thanks, Don) indicated that Birmingham was far to close for a QSO, but Don ‘spotted’ me. Eventually a QSO with ON5WAB resulted, badly affected by QRM from an adjacent (French) station, but I was warned that ??5NEP (?) was also calling, but was unreadable due to QRM.

A few questions arise:

  1. Was everyone else at the rally?
  2. Did anyone think they heard my calls on 80M?
  3. Were HF conditions generally poor about 13:00 UTC?
  4. Is there any benefit in getting the far ends of the antenna a metre or so above the ground - mine were attached to plastic pegs in very dry ground.

Comments would be appreciated.

Regards, Dave, M0DFA


#2

In reply to M0DFA:

Dave

Various sources show that the ends of an antenna should never be less than 1/30 of a wavelength above the ground. Pegging them to the ground is a very bad idea indeed!

CW gives an advantage of roughly 13dB (equivalent to a x20 increase in power) but you knew that anyway.

D layer attenuation peaks around solar mid-day on 80m.

73

Richard
G3CWI


#3

In reply to G3CWI: Thanks for info on the optimum height of the ends of the antenna above the ground. I knew I’d find a use for a pair of walking poles eventually!

CW - Wasn’t aware of the numerical benefit of CW, but the reduced bandwidth (I’ve fitted the 300Hz filter to the FT817) must be of advantage in a busy band. I’ll get there one day.

73s, Dave, M0DFA


#4

In reply to M0DFA:

Thanks for info on the optimum height of the ends
of the antenna above the ground.

Dave

It’s MINIUMUM - NOT OPTIMUM!!

73

Richard


#5

In reply to M0DFA:

Personally I’d junk the feeder, tuner and antenna and replace them with a link dipole cut for the frequencies you want, fed with RG-174 or RG-316. Less to carry, less to go wrong, less loss for your signal. You don’t need to be able tune the whole of each band either. Just a few spot frequencies on each band will do.

Do keep the ends clear of the ground. I’ve done about 37 successful HF activations. My dipole ends are some lightweight plastic insulators with about 3m of 3mm nylon rope. Most of the time I can tie the fishing pole to a fence and the ends tied off on the fencewire. Typically the ends are then about 1m above ground. Of course you can’t rely on a fence and this is when the ends of the antenna end up about 30cms above ground. It’s noticeable from reviewing the log that reports are always down when the antenna ends are nearer the ground.
2S points lower springs to mind.

3mm rope is about the thinest I can manipulate with gloves on. Any thinner and you need to remove gloves. I’ve tried to design my setup so I can put it up/take it down with my gloves on. Taking gloves off on Scottish summits in the winter is counter-indicated :slight_smile:

It would be interesting to measure the loss across the tuner for the antenna you have. Could be an eye-opener! Maybe less of an issue if you plan on CW activations but the loss could be significant on SSB with only 5W.

And commiserations that you had a less successful activation than you expected. It’s really miserable when you put effort in and don’t get the reward you expect. I hope you have much better success next time.

Finally consider 60m. You can rely on a super enthusiastic bunch of chasers to be waiting. They’ll help you get get the summit activated with ease on 60m and then you can use them to make a noise on other bands with their QRO setups to clear up some space for your less potent signals to stand a chance. That way you can get the worry and hassle of getting the summit activated out of the way and spend the rest of the time having fun on the bands.

Andy
MM0FMF


#6

Hi David,

It was not ON5WAB you worked but ON3WAB. QRM was indeed terrible but I was glad to be able to exchange reports. I know that when the french station stopped transmitting you were 54 and perfectly readable. He was just too close to your frequency and whiped you out completely.

The french station that called you was Lionel, F5NEP

Hope to catch you again

de Peter

ON3WAB


#7

In reply to M0DFA:

I tried HF today from SP-015 around teatime & it was hopeless. 4 contacts on 40m ssb, nothing at all on 60m after 10 min calling on FE, 10m sounded great as I checked it, but when I eventually qsy`d there it had died - just 1 Lancs station & an OH. Had to resort to 2m FM to get the tally up to 19 contacts. I agree with Andy - go for a linked dipole, no tuner so less weight & less to go wrong. GW4BVE put some pics of his dipole on flikr the other day.
73 Steve G1INK.


#8

In reply to G1INK:

Does anyone use a balun with their dipole? if so what type? Or just connect the coax direct like it tells you not to in all the books and learned articles?

de Paul G4MD


#9

In reply to G4MD:

I sometimes use a feedline choke on my portable dipoles but it is not really necessary unless you want the radiation pattern to be (more) exactly as predicted. I can never recall anyone coming back to a CQ and complimenting me on the great job my feedline choke is doing…

Feel free to omit them for portable operation. No-one will notice and we wont tell!

73

Richard


#10

In reply to M0DFA:

Dave

Your signals were strong into Scarborough when we logged you as MW0DFA at 1240 UTC. Conditions on HF were not good today, we operated on 80m from 0800 until the band died early at about 0900. A move to 40m produced good sigs around the UK until 1200 then the skip became long and it was mainly EU stations for the remainder of the day. Thunderstorms around Europe made for a noisy band with QRP stations struggling to make contact.

Not a good day for reliable antenna tests.

73
Roy G4SSH
Station manager
GB2CAT


#11

In reply to MM0FMF:
Personally I’d junk the feeder, tuner and antenna and replace them with a link dipole.

I just went for the doublet to use all the wire I had in the air.

Do keep the ends clear of the ground.

Point also made be G3CWI

Taking gloves off on Scottish summits in the winter is counter-indicated
Not much better in GW - land, or G/SE on the bad day which is the only
chance you’ve got. I’ve ofter wondered how the artic/antarctic guys manage
to keep records outdoors. My XYL can usually find something urgent for me to
do when it’s really cold (HI)

It would be interesting to measure the loss across the tuner for the antenna you have.

Good point - I’ll try it.

And commiserations that you had a less successful activation than you expected
Thank you. The main reason for going out onto a very easy hill was to check
the set-up. Not really enough room away from my main doublet antenna at the
home QTH. If I’d really wanted the summit I’d have put up the 2M J-pole. As
it is, I can do it all on 2M one Tuesday evening, not that it’s a very good
summit for 2M. GW/MW-027, a couple of miles north across the valley is much
better.

Finally consider 60m.

A bit like jumping on the bandwagon, and can’t think of an original reason
for wanting the. NOV Also means getting my recent FT817ND openned up - a
solder job which I’m not competent to do, and the nearest place to me is
Castle Electronics who quoted £40 to do it. Wish I could get £40 for 5
minutes work!!

Many thanks for your reply

73 Dave, M0DFA


#12

In reply to ON3WAB:
Thanks Peter - I’ll correct my log and the database entry. Now I’m home, I realise I should have looked for a better frequency and QSYd.

73, Dave, M0DFA


#13

In reply to G1INK:

Thanks, Steve. Glad to hear I’m not the only one. Mind you, it was very pleasant on the top, which is why I stayed as long as I did. I’ll have a look at John’s pictures, but I would like to use something different from everyone else.

73, Dave, M0DFA


#14

In reply to G4MD: So far as I can see (and I’m sure the experts will correct me) the only reason for using a balun to connect to a dipole is to force the return current into the inside of the coax shield, making the dipole behave as a balanced radiator by preventing radiation from the outside of the coax screen. As I understand it, a couple of turns of the coax round a suitable ferrite ring works by putting a high inductance in the outside of the coax shield, alternatively, threading some small ferrite rings over the coax does the same thing.

I’m sure someone will now disagree

73, Dave, M0DFA


#15

In reply to G4SSH: Thanks you. You’ve got the point for the SOTA chase, even though I didn’t complete that activation. Perhaps I should have stayed at home and fought the weeds in the garden!

Best 73s, Dave, M0DFA


#16

In reply to M0DFA:
Hi Dave

I certainly wouldn’t disagree with anything you say! Just wondered if anyone bothered - to my mind the last thing you want is an extra lump of something heavy swinging around at the top of one’s Sotapole.

Thus far I have used computer ribbon antennas using the ribbon as an open wire feeder (a la Norcal) and an ATU for HF activations, but will definitely have a go with an RG174 fed dipole in the near future.

Better luck on your next HF activation!

73 de Paul G4MD


#17

I had a go at 7MHz SSB today from my second summit. Clear frequency, maximum power, self-spotted on the clear frequency and an antenna that I knew was working. Result? Absolutely zilch.

This was immediately after QSYing from the CW part of the band where I was working EU stations every 2 minutes (only 12wpm) with 599 reports both ways in most cases. Richard quotes the 13dB advantage - are there any other reasons why SSB is soooo difficult compared to CW? Any tips on how I can improve my HF SSB performance running 5 watts? (No, I’m not going to buy an 857).

I had to resort to 2m FM in order for Jimmy to qualify the summit! He still has Kisdon G/NP-026 at the forefront of his mind, and is now becoming more open to the idea of learning some (very) basic CW to finally qualify this elusive summit!


#18

Richard quotes the 13dB advantage…

With apologies to all those who havent seen the light… CW really does make a huge difference when power is low and/or signals are weak.

My home station is low powered, usually 10W with the following experiences since it was set up at this QTH last November:

SSB - Always tough and never relaxing
RTTY - Does OK (ish)
PSK/Other digimodes - Does OK
CW - If I can hear them, I can generally work them with 10W! (unless it’s a huge pile up populated by many Europeans who only run 1KW+)

Actually there are US stations I used to work during CW contests when I lived in the US who I know use their 1.5KW legal limit. I’m still working them here with my 10W CW… OK I know they have their stacked 4 ele beams on 40M but hey it’s still 10W!

So I would endorse the 10-13db advantage… and I was dragged kicking and screaming to CW… took me ages to start using it after my test. But now I would always try it first… and it’s fun.

73 Marc G0AZS


#19

In reply to G4MD:

Just wondered if anyone
bothered - to my mind the last thing you want is an extra lump of something
heavy swinging around at the top of one’s Sotapole.

Well I wasn’t sure if it would be good or bad to do without a choke. So I made one out of 5 turns of feeder. You have to wind the coil like a solenoid for it to work properly, higgledy-piggledy doesn’t work aswell. So there are few plastic stays and tie wraps to hold the solenoid together. I just weighed it… the feeder (approx 10m), the solenoid, BNC and the centre piece were the two dipole legs attach weighs 200gms. I could probably save a bit of weight in the centre piece, but the system seems durable so far.

There’s a picture at http://www.flickr.com/photos/51647830@N00/539481157/
The red tape is double sided Velcro which is great for lashing things to SOTA poles. The centre piece has 2x 4mm connectors that each dipole leg connects to. The feeder is RG-174 and the termination at the BNC plug was tricky as it was designed for RG-58 thickness cable. I used some heatshrink tubing over the cable and BNC plug and filled up the inside of the plug with hotmelt glue. It formed a rigid lump that holds the thin coax in place. As it was hot the heatshrink shrunk forming a solid and watertight seal. I used yellow so I can see it easier.

The antenna is thin PVC wire and it doesn’t have much bandwidth. So 40m best SWR is on 7.090MHz and starts to get ugly near 7.05. OK on 7.115MHz. On 60m best SWR is on 5.3985MHz and is getting noticeably high on the bottom channels. The antenna does the job for SSB working and will need attention when I have got my Morse upto something presentable and I give operation on 7.032MHz a bash. Some Palm Paddles are on the shopping list for Friedrichshafen :wink:

John GW4BVE used a ferrite core for his choke. I’m not sure which is lighter or works better. An inverted V is meant to be omni directional and mine seems to give the same results no matter how I have oriented it on the hills. Today I had a contact with Jack GM4COX at about 20miles distance on 60m. He said there was heavy QSB on the signal which suggests significant skywave component so I think it works as an NVIS antenna. I can normally work all the SOTA ‘DX’ (G0RQL, G4GKE, G8BKE all on the South coast) at 300+ miles. So it works as an inter-UK SOTA antenna. I haven’t done enough on 40m to comment, 5W SSB on such a noisy busy band is hard work hence my interest in getting my Morse back to speed.

There’s no right solution to selecting an antenna for SOTA. This one happens to work well for me.

Andy
MM0FMF


#20

In reply to M1EYP:

Any tips on how I can improve my HF SSB performance running 5 watts?

  1. Speech processor: use a SSM2165 mic processor.
  2. More antenna gain: use more wire
  3. Get someone with a big signal to act as net control on 40m to keep the neighbouring frequencies clear and to stir up interest.

Andy
MM0FMF