SWR question on Temporary set up

Hi there.

I'm trying to get a more permanent set up in this new house but having a few difficulties in the loft, so I thought I'd pop up the old T2LT on a 10 meter fibre glass flag pole (my CTX kit) outside the back of the new house just to get going - however.... I've worked the SWR and lengthened and shortened (in the correct manner) but can only get the SWR's on muppet 1+40 to equal out at about 3.0 - AT5555 rig.

I've never had this before, I've always been able to bring them to <1.5 by lengthen/shortening the top of the dielectric, (albeit out in the open on a hill top somewhere) but the best I'm getting here is both at 3.0

The antenna is in the corner of two joined houses on a 90 degree bend and is only a few feet from the wall, but the air choke is just above the guttering.  I can't put it anywhere else yet. The gutters are plastic but the mounts for the gutters are metal.

Is there any way to bring the SWR down as obviously i won't be transmitting at SWR 3.0?
Is it the building being so close thats possibly causing it?
Also, the SWR reading on the AT5555 is not the same as the Moonraker SWR meter.  The Rig is giving much lower readings - could it be a dodgy SWR meter, are the internal Rig meters quite accurate?

Any help appreciated - Thanks.

I'll try to post a photo - hope it works...

Matt - CT/X6657

Never used that rig so can't comment on the SWR meter but does it look like there is a dip in the SWR anywhere on the bands? The T2LT is up in the clear enough by the look of it that it shouldn't skew the match all that much.

Hi Matt, one thing to consider looking at the photo have you shut the window on the coax as that could have damaged it
73s
Steve.

StevieG wrote:

Hi Matt, one thing to consider looking at the photo have you shut the window on the coax as that could have damaged it
73s
Steve.

Thanks Steve. The COAX was loose through the window at all times.

Cheers,

Matt

26TC62 wrote:

Never used that rig so can't comment on the SWR meter but does it look like there is a dip in the SWR anywhere on the bands? The T2LT is up in the clear enough by the look of it that it shouldn't skew the match all that much.

Thanks,

I'll have a look around the bands as I've been away for a week.  I'm pretty sure it was at its lowest on the UKCB and higher on the others either side.

I have since put up a UKCB 27Mhz tuned Horizontal Dipole in the loft and I have exactly the same problem - The SWR's are both high (around 3) on all the UKCB frequencies ...  I'm just not sure what to do, I have never had this situation before where they are equal but to high to transmit.

Any help or advice would be appreciated.

Thank you.

Matt

hawk657 wrote:

26TC62 wrote:

Never used that rig so can't comment on the SWR meter but does it look like there is a dip in the SWR anywhere on the bands? The T2LT is up in the clear enough by the look of it that it shouldn't skew the match all that much.

Thanks,

I'll have a look around the bands as I've been away for a week.  I'm pretty sure it was at its lowest on the UKCB and higher on the others either side.

I have since put up a UKCB 27Mhz tuned Horizontal Dipole in the loft and I have exactly the same problem - The SWR's are both high (around 3) on all the UKCB frequencies ...  I'm just not sure what to do, I have never had this situation before where they are equal but to high to transmit.

Any help or advice would be appreciated.

Thank you.

Matt

Matt can you confirm you're using an external SWR meter and not the one on the radio?

73's Gary.

Hi Gary.

Yes, I have an external SWR/PWR meter (only a basic model). The SWR meter is showing pretty much equal SWR 3 on ch1 and ch40. The strange thing is the AT5555 rig internal SWR meter is showing a lot lower SWR's.

Cheers.

Matt

Are both these antennas in free space well clear of any metal objects that could be affecting your readings?

If you follow the measurements for a dipole it's almost always spot on. If you mount it in an inverted V configuration they will require shortening a little.

I would also have a 1:1 balun on your dipole or an air choke like the T2LT

I have heard of people having trouble getting the SWR on T2LT's to a useable level. Mine tuned first time.

I guess you should go back to the start. Check all connections cable and plugs and remake the antennas if need be.

One last thought is that pole fiberglass? If it's carbon fibre it's not suitable to mount the antenna on?

73's Gary.

C.T. Admin

GaryWilson wrote:

Are both these antennas in free space well clear of any metal objects that could be affecting your readings?

If you follow the measurements for a dipole it's almost always spot on. If you mount it in an inverted V configuration they will require shortening a little.

I would also have a 1:1 balun on your dipole or an air choke like the T2LT

I have heard of people having trouble getting the SWR on T2LT's to a useable level. Mine tuned first time.

I guess you should go back to the start. Check all connections cable and plugs and remake the antennas if need be.

One last thought is that pole fiberglass? If it's carbon fibre it's not suitable to mount the antenna on?

73's Gary.

C.T. Admin

Thanks Gary.

Yes my T2LT and the DiPole both have standard size air chokes.  

The T2LT on that fibreglass pole has worked perfectly in the past on CTX set ups.  

The company I purchased the Dipole from states it does not require a balun.

I've checked all connections today on all connections including the patch lead and all are good.

I also checked SWR from 26.065 all the way unto 28.305 checking the equivalent channels 1 and 40 all the way up.  The strange thing is that the SWR meter on the rig is varying quite wildly from the independent SWR meter - results below.

I have now also lowered the Horizontal Dipole height in the loft down to take it away from the metal beam joints in the apex.  It now hangs equidistant from the apex to the floor of the loft - but with no change in SWR at all.  Its hanging in free space with ceramic insulators on each end tied with garden string to plastic coated bungees at either end to keep the tension.  The only other metalwork up there is the cables that run along the loft floor for the roof lights and extractor fans in the upper floor.

SWR meter reads 1 to 1.5 then 1.5 to 2, then 2 to 3, where it turns red and has no more indications except the red band all the way to the top of scale.

                          INDEPENDENT SWR METER READS              ++++++                       RIG's SWR READS

26.065 -               Top of Red bar (all the way right scale)       ++++++                       2.4
26.505 -               Top of Red bar (all the way right scale)       ++++++                       1.9

26.515 -               Top of Red bar (all the way right scale)       ++++++                       1.9
26.955 -               Half way up the red scale  approx 4            ++++++                       2.0

26.965 -               Half way up the red scale  approx 4            ++++++                       2.0
27.405 -               3.2                                                          ++++++                       2.3

27.415 -               3.2                                                           ++++++                      2.3
27.855 -               3.0                                                           ++++++                      3.0

27.60 125 -          3.1                                                            ++++++                     2.6
27.99125 -           3.0                                                            ++++++                     3.2

27.865 -              3.0                                                             ++++++                     3.0
28.305 -              3.0                                                             ++++++                     4.0 (approx half way up red scale bar)

Could it be a faulty SWR meter?  It is a few years old and has been in storage for 4 years.  

I'm stumped.

Cheers.

Matt

Further to this today I have swapped rigs to a Midland Portapack (just incase it was my AT5555 causing issues)- with the same results.

Also the using 26.065 and 28.305 readings of off the scale and 3 (bottom of the red scale), I lengthened the antenna by 0.5 inch and then again by 1 inch per side there is no difference at all in any of the numbers throughout the 26-28.  I have also swapped patch leads to no avail.

The figures just keep coming in around the 3.0 on the UK40

Double stumped.

Matt

Hello Matt.

Firstly yes the SWR meter could be faulty if its been in storage and particularly if it's a cheapo one. Is there anyway you can check an antenna you know is tuned or borrow a working meter of a friend?

On your rig it looks like there's a dip at the top of 26mhz to the bottom of 27Mhz which is a fair bit lower than the UK40. If you add length to the dipole it will take that resonance even lower and further away from the UK40.

I would buy another SWR meter and see what results you get. You need by the looks of it to shorten the antenna to take it's resonant frequency up the the UK40. There doesn't seem to be a spot where it drops to 1-1.5 so I still think you may have another problem.

My 11 meter dipole doesn't really change SWR very much wherever I put it so it might be worth trying outside in the garden to see if that makes any difference.

73's Gary.

Thanks Gary - I will try all of the above and report back.

Unfortunately I have just moved here literally in the last month, so I will order a new SWR meter from Knights ASAP as that is the only thing I can think of.

I only have a very small garden but will look at trying it out somehow outside. I may just attach it to the top of the wooden fence separating me and my neighbour as that is long enough to hold it. Its only 2 meters above ground and surrounded on two sides by the brickwork of the house ... but at least if the SWR changes.... thats a start.

Cheers.

Matt

Hi Matt, yes I think that's a good start. For ages I had a dipole in exactly that position it worked surprisingly well! Much better than in the loft which whatever people say is about the worst place you could put your antenna.

Do let us know how it goes.

73's Gary.

Thank Gary.

I've ordered a better quality meter from Knights, and I've returned the length to exactly 'from the factory' where the report sheet issued with it showed it to be 1.1

I'll stick it on the fence tomorrow evening and see what happens there first.

Cheers  

Matt

GaryWilson wrote:

Hi Matt, yes I think that's a good start. For ages I had a dipole in exactly that position it worked surprisingly well! Much better than in the loft which whatever people say is about the worst place you could put your antenna.

Do let us know how it goes.

73's Gary.  

Hi there Gary.

Well, what a week.  Banging my head off every wall in the loft with this SWR problem!

I bought a new SWR meter and there was a slight change, but SWR still up in the RED.
I tried the dipole on the fence outside with - no change in SWR, still RED.
I tested again all the patch leads and the coax - no change in SWR, still RED.
I tried changing rigs - no change in SWR.
The only thing i didn't test/check ....was the brand new professionally built Dipole ...

So, i took it down and opened it up to find this ... PHOTO A



Straight away I could see braiding touching across both internal sides of the pin, so clipped the loose wire.  I then looked carefully and buried in their glue on the top of the dielectric, I could see another tiny piece of wire, once again joining the braiding from right to left .  If you look carefully (zoom in) just under where it says 'HERE' on photo B... you'll see the stray wire buried in the glue.



So, took the glue off to find two small pieces of the outer braiding connected to each other across the split braid.  So clipped both of them and got rid of the glue so it now looked like this - Photo C.



I then tried the SWR tests ranging from 26.065 right up-to 28.305 just to see if it helped ... AND BINGO!  It was ALL OUT of the RED!  (SEE COLUMN 1 IN THE NEXT PHOTO FOR THE FIGURES)

So, last night I plotted out the SWR's starting with the length the antenna came set at.  Not ideal, all ranging between 2 and 3, but out of the red and not banging off the scale of the SWR meter as previous.

I purchased the antenna as a 27Mhz DXer... and when i measured the length of the antenna it was set at 96" per side.  After a little research and using two different Di Pole calculators, I notice that the length of each side of the dipole should be approx 103" for the 27Mhz area.  This dipole was at 96" per side.

So I lengthened it toward 101 inches (the maximum I could extend it to) and tried again. But the SWR's were slightly higher. (SEE COLUMN 2 IN THE NEXT PHOTO FOR THE FIGURES)

After plotting out these figures, I could see where the SWR was lowest and then started re adjusting it 5 more times to eventually settle on a length of 92 inches. (SEE COLUMN 8 IN THE NEXT PHOTO FOR THE FIGURES).  

I re did the 5 turn RF choke and it dropped further - Column 7.  Not ideal but workable and certainly not banging off the scale !





My conclusion is that the workmanship (of this brand new antenna) on the inner junction box was terrible and was basically shorting which caused the initial 'Needle Banger!'.  As for the size ... i'm not sure, maybe they sent me the wrong length for the wrong band?  I don't know.  I do know that I will be making my next one and will never trust a brand new, hand built bit of kit again!

I now have workable (I can actually transmit safely!) SWR's all below 2 in the areas that I need them most, and straight away found a QSO with a great signal report from about 10 miles away.

If nothing else, it has taught me quite a lot about SWR and also seeing the power that is lost due to high SWR (from my new meter) was also quite an eye opener.

I'm back on the air !!

Cheers Gary, and to all that replied.

Matt
CT/X 6657

Well done Matt, a well executed breakdown glad you got to the bottom of it. Great statement "Never trust new kit" especially in radio use as it's very easy to do a lot of expensive damage instantly, a lesson and reminder to us all.
Great work enjoy the fruits of your labour's,
73s
Steve.

Nice one Matt and happy days




Craig

hawk657 wrote:

GaryWilson wrote:

Hi Matt, yes I think that's a good start. For ages I had a dipole in exactly that position it worked surprisingly well! Much better than in the loft which whatever people say is about the worst place you could put your antenna.

Do let us know how it goes.

73's Gary.  

Hi there Gary.

Well, what a week.  Banging my head off every wall in the loft with this SWR problem!

I bought a new SWR meter and there was a slight change, but SWR still up in the RED.
I tried the dipole on the fence outside with - no change in SWR, still RED.
I tested again all the patch leads and the coax - no change in SWR, still RED.
I tried changing rigs - no change in SWR.
The only thing i didn't test/check ....was the brand new professionally built Dipole ...

So, i took it down and opened it up to find this ... PHOTO A



Straight away I could see braiding touching across both internal sides of the pin, so clipped the loose wire.  I then looked carefully and buried in their glue on the top of the dielectric, I could see another tiny piece of wire, once again joining the braiding from right to left .  If you look carefully (zoom in) just under where it says 'HERE' on photo B... you'll see the stray wire buried in the glue.



So, took the glue off to find two small pieces of the outer braiding connected to each other across the split braid.  So clipped both of them and got rid of the glue so it now looked like this - Photo C.



I then tried the SWR tests ranging from 26.065 right up-to 28.305 just to see if it helped ... AND BINGO!  It was ALL OUT of the RED!  (SEE COLUMN 1 IN THE NEXT PHOTO FOR THE FIGURES)

So, last night I plotted out the SWR's starting with the length the antenna came set at.  Not ideal, all ranging between 2 and 3, but out of the red and not banging off the scale of the SWR meter as previous.

I purchased the antenna as a 27Mhz DXer... and when i measured the length of the antenna it was set at 96" per side.  After a little research and using two different Di Pole calculators, I notice that the length of each side of the dipole should be approx 103" for the 27Mhz area.  This dipole was at 96" per side.

So I lengthened it toward 101 inches (the maximum I could extend it to) and tried again. But the SWR's were slightly higher. (SEE COLUMN 2 IN THE NEXT PHOTO FOR THE FIGURES)

After plotting out these figures, I could see where the SWR was lowest and then started re adjusting it 5 more times to eventually settle on a length of 92 inches. (SEE COLUMN 8 IN THE NEXT PHOTO FOR THE FIGURES).  

I re did the 5 turn RF choke and it dropped further - Column 7.  Not ideal but workable and certainly not banging off the scale !





My conclusion is that the workmanship (of this brand new antenna) on the inner junction box was terrible and was basically shorting which caused the initial 'Needle Banger!'.  As for the size ... i'm not sure, maybe they sent me the wrong length for the wrong band?  I don't know.  I do know that I will be making my next one and will never trust a brand new, hand built bit of kit again!

I now have workable (I can actually transmit safely!) SWR's all below 2 in the areas that I need them most, and straight away found a QSO with a great signal report from about 10 miles away.

If nothing else, it has taught me quite a lot about SWR and also seeing the power that is lost due to high SWR (from my new meter) was also quite an eye opener.

I'm back on the air !!

Cheers Gary, and to all that replied.

Matt
CT/X 6657

Hello Matt,

Well done mate you did a fine job in solving that one! Radio is always a process of learning and like you said you know know more than you did before.

The construction of that dipole was disgusting and lets be honest they're not exactly difficult to make!!! The best thing to do is make them a little longer than needed and bend the ends back on themselves for tuning purposes. Remember in a inverted V configuration they will always need to be shorter anyway and the height off the ground will make a difference as well. An SWR of about 1.5 should be easily achievable anything under 2 is workable.

First contact 10 miles not bad at all radio really is marvelous isn't it. There's been some good E-skip openings this week so get ready to make some contacts in to Europe!! Best of luck.

73's Gary.

Nicely done Matt!

Brilliant sharing your experiences and the learning along the way, could do well to help others too. (Can't believe the appalling construction in a so called saleable item....not even the basic checks performed on that!!)

Keep at it mate, you will be rewarded

If it helps any for future DX hope - I have a homemade wire inverted V dipole inside my loft and very recently made a contact to Germany! Far more pleased with that effort than if I'd purchased an antenna

All the best,
Victor

Cheers all !!

I'm going to make one myself this month and compare them in a test against each other ... :-)

If anyone is interested.. here's more detail on my YT channel.

https://youtu.be/bmy_6hYotGs

Thanks again all :-)

Cheers.

Matt