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Equipment discussions, questions, answers.  Focus in on QRP and backcountry operation, but anything equipment related goes.


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ZL2OZ posted in Equipment on 2021-02-18 13:20

Hi Simon, I've tried to order some, but they don't like credit cards. Pity.

ZL1THH updated in Equipment on 2021-02-18 10:08

Great link to the DOC wire. thanks Stan, 

ZL1RKO just received some, and see how it is actually braided wire, not twisted. The yellow bits are plastic that sticks there when stripped (which Charles reports is a bit of a bugger)

----

I was wondering just how much stronger hard drawn wire is.....

"Hard drawn copper has significantly higher tensile strength than soft annealed copper and is used as overhead wire whereas the soft annealed copper is flexible and has somewhat improved conductivity over hard drawn copper conductor.  

Annealed copper - Tensile strength 300-400 ksi (kilopound per square inch). Conductivity 100.00 % IACS

Hard drawn copper - 500-700 ksi. Conductivity 97 % IACS"


6796cc9e c75c 4344 89ff b954cb49b1a5 original original

ZL1THH updated in Equipment on 2021-02-13 14:53

I used stranded cat5 network cable, with the pairs untwisted. The polyethylene is hard and slippery, as you would want, and you get a bunch of colours - I used one colour for the first 20m and another for the second 20m.

It's super cheap and available, which somewhat cancels out any issues of strength and uv resistance. 


OD=0.95mm, ID=0.5mm. 
Breaking strain 5.5kg
Stretching strain ~4.5kg.
Weight 40m=100g  (2.5g/m)

For centre-fed dipole users you could also use the twisted pair as feedline. It is 100ohm, low loss. 
Cat5 30m=7dB@100MHz  , 5g/m
RG174 8dB , 13g/m
RG178 14dB , 7g/m

-------
Method: 
Need 3 fishing swivels, 300mm wood, cardboard ~150mm sq, a helper to hold the end.
Put a drop of oil in the swivels. Cut a dual winder/s from a bit of cardboard before you start. Find a long enough space without sticks, and rubbish.
Strip the cat5 apart to get the pairs. It would probably be a good idea to use a swivel at the end of the cat5 while you do this, as the bundle is twisted.

Now unwind the pairs: 
At one end fix two swivels to a piece of wood some distance apart eg 300mm. Tie the individual strands to these. 
At the other end tie the twisted pair to the third swivel and tie it to a hook/nail. Don't just put it over a nail, it won't be as free.
Now from the two swivel end gently pull the strands apart, moving along. All 3 swivels will be turning while you do this.




20210213 110426 1  original original

20210213 104720 1 1  original original

20210213 110426 1 1  original original

20210213 144352 1 1  original original

ZL3TK updated in Equipment on 2021-02-11 18:23

Many years ago the ideal wire for portable HF operations could be found at CASA Modular Systems in Petone.  It was alleged to be NOS from the Department of Conservation and was used with DoC's HF portable stations.  Amazingly, it is still available as shown at http://casamodularsystems.com/index.php?main_page=product_info&cPath=1_216_257&products_id=209 ... and is described as "Aerial Wire - 8 strands of 0.25mm Braided Hard-Drawn-Copper with tough YELLOW PVC Jacket - 2mm OD (typically supplied in multiples of 10m or random lengths - while stock lasts)"   But the price has increased markedly;  guess it is now new stock rather than the original NOS.   It is very light-weight, multi-strand hard-drawn copper wire in a bright yellow, never-fade, flexible PVC sheath, therefore is highly visible in the bush and will never stretch in the wind  -  resonance, as cut, is guaranteed long term.   See also there is a spool available;  it used to be provided as a wire-and-spool package for about $25;  no longer unfortunately and despite being beautifully engineered, the spool may be considered too bulky to carry around in a pack anyway.  Take a look while stocks last.




Casa hdc wire yel 100m original original

ZL2STR posted in Equipment on 2021-02-06 17:26

HI All
Would be interested to know what others are using to make their wire antennas from, for portable Qrp. Is there a supplier in NZ that sells similar to sotabeams wire or is there something better. Look forward to your replies
Cheers and regards
Stewart ZL2STR

ZL2STR posted in Equipment on 2021-02-02 16:54

Hi Simon
I would be interested in one of your Perch Poles.
Address is
6 Willow Ave, Stoke, Nelson 7011
If you email me strobnz@gmail.com with costs including postage I can do a online banking for you
Cheers and regards
73
Stewart Robinson ZL2STR

ZL2STR posted in Equipment on 2021-01-29 14:23

Planning trip tomorrow 30th and hope to be on air 1200 from Lake Guyton hit and the Go WRP night at Pool Hut. Hope to hear from you
Stewart ZL2STR 

ZL2STR posted in Equipment on 2021-01-29 14:17

I’m keen. Will make contact when home Tuesday
Stewart ZL2STR

ZL1THH posted in Equipment on 2021-01-27 15:58

I just got some telescopic poles ("perch poles") from CN, and have a couple extra. 

They are fibreglass not carbon. 350g. 65cm collapsed length is easier for packs/bush than the ones I got locally.
7.2m spec: means 6m (possible as a vertical), 5.5m holding a light dipole.

$32 if anyone here wants one before I put them on Trademe.

ZL1THH posted in Equipment on 2020-12-29 10:33

For anyone interested, I broke down the 817 and weighed it all, looking for savings to make it light enough to take on a long trip.  Hoping to get it to ~700g with batteries.

- Covers are 300g: replace with carbon
- Energizer Li AA's lightest choice that I can get in time.
- Microphone is 170g
- misc parts: speaker bracket, spkr, so-239
- lighten chassis


ZL1THH posted in Equipment on 2020-12-09 15:52

You just put a high value R across the line for static. Just has to have breakdown voltage greater than max for your transmitter at VSWR=N

You don't use a spark gap to discharge static, as it is making RX noise.

ZL4NVW updated in Equipment on 2020-12-06 16:40

I've just fitted an inductive 133uH discharge coil from feedline core to ground at the base of the mast for my 80m dipole - 100 turns of antenna wire on a length of 40mm plastic pipe. Which will hopefully work to discharge static from the non-grounded half of the dipole without passing RF (comments on the value welcome, just went off a comment that '100 turns on a beer can should be enough (then remove the can)') .  Unfortunately my antenna <1.5:1 SWR band seems to have dropped from 140kHz to 100kHz either side of centre - though at the low point is still 1:1 at the usual tuned centre freq of 3.650. Not sure if that's the result of the coil, or due to something else, but is annoying.  Solves the static, but not the lightning risk.  Will build another for the (40m/15m)-20m-17m fan dipole.

Separate conversations here (https://forums.qrz.com/index.php?threads/lightning-static-buildup-protection-for-efhw-on-house-gable.737891/) have convinced me that the EFHW coax run needs re-routing down to ground outside the house rather than through the loft-space so that it can get effectively grounded at the choke.  As I should have realised the UNUN (matching transformer) on the EFHW provides a low-resistance DC path between core and shield so the discharge device connected to the feedline core is not required for an EFHW so long as the shield is grounded at the choke.

All of which is about static buildup, and none of which deals with lightning strike. The spark plug sounds like a good cheap option.   I was getting a good 15mm spark gap between centre-pin and casing yesterday. The gas-discharge lightning protection devices cost more each than my Kenwood cost me by the time they're converted to NS$ and landed in NZ.
 

ZL2OZ posted in Equipment on 2020-12-06 11:17

 We don't get lightning often here in Dannevegas, but it can be a doozy when it arrives. I too just remove the antenna from equipment. but would like to install some form of lightning protection. I don't like seeing sparks jumping from the antenna plug to any metal object within 10 to 15mm! A bit scary! Oh, and painful if your handling it at the time of a strike!! Suggestions? (Apart from 'Don't handle it!'

ZL1LC posted in Equipment on 2020-12-06 09:31

You don't have to be in a thunderstorm to have a shocking experience with an antenna.  


When I was an apprentice in a desolate place called Waiouru, we had a dipole strung up outside the workshop.  It had the braid of the coax grounded and tapped onto the center wire of the coax was a spark plug with a 0.030" inch gap.  (No metrics for me, so I'll let someone figure it out.)  In the winter, when the snow clouds were down low, that spark plug was zapping away all day as it discharged the static electricity that had built up on the antenna.


We don't normally get the huge lightning strikes that they get in the USA, because our humidity is higher, so I suggest as a good starting point, you need to start reading some of the ARRL handbooks.  Having a high wattage 100k ohm bleed resistor across the antenna to ground is a good start, but you need a fast DC (low resistance ) path to ground if there's any close lightning.  


The best solution is not to have your radio connected to the antenna during a thunderstorm.  That keeps the expensive item safe.  Fixing an antenna or coax is a lot cheaper and simpler.


73

Jim  ZL1LC

ZL4NVW updated in Equipment on 2020-12-06 09:31

Not specifically QRP related but ... 

Last night in a particularly heave rainstorm I was sitting at the computer listening to what sounded like an arc-ing electric fence inside of my antenna switch. 

Disconnecting the antenna cable proved to me quite emphatically (shockingly, even) that this was electric discharge happening from the core or the coax / connector coming from the antenna to the case & thus earth.

Dipoles:

The shield of the feedline is grounded at both mast and shack - but the core obviously not.  I had been disconnecting at the mast when away and when lightning was forecast - but clearly that's not good enough. 

  • Putting static discharge coils between mast-ground and the cores of the 2 dipole feedlines is a no-brainer.  
  • These presumably really should have some arc-gap or similar lightening protection too ...

End-fed half wave:

  • Feedline shield is grounded at the shack only (there is no mast) 
  • Feedline core is not currently protected at all
  • The unun is on the house gable with no ready access to ground and whilst I can run a static discharge ground cable down the outside of the house, I suspect that running something sufficient to ground a lightning strike is less simple and aesthetically acceptable

So 2 questions:
1) What would you you do to safely discharge & protect an EFHW?  
2) What arc-gap or similar lightening protection devices do you use and is any of it available in NZ?


Matt

ZL2BH posted in Equipment on 2020-10-20 06:21

Jim, What a cool device you have made and thanks for the tips re the wire etc
John
ZL2BH
I inquired to the guys at QRPver to see if their single-band QRPver1.3 radio can be extended out to receive the mountain radio service frequencies.  The default radio covers only the the 80m amateur band on both tx and rx - but for my backcountry use the ability to receive the nightly mountain and long-range weather forecast on 3.261 / 3.345 USB is a necessity.

The response was that yes - this can be done so long as you let them know before you order.  I hope the info is of use to someone.

Note that I did not inquire about transmission on the mountain radio service frequencies.

Email trail is below


Matt - ZL4NVW

===



Hi dear Matt
Yes, it can be done during the manufacture of the device. You just need
to contact us before ordering.

Regards, _____

73!

21.07.2020 23:41, Matt Briggs - ZL4NVW пишет:
> Hi,
>
> I'm interested in your 80m qrpver1.3 which seems to work very well on 80m.
>
> However in addition to the 80m amateur band, I also need to be able to receive the 'mountain radio service' weather forecast broadcasts on 3.261MHz and 3.345 MHz, USB.  Is it possible to open up the receive on the 80m radio to receive these?
>
> If you are able to do this, I am sure that you will receive many more orders from New Zealand - as being able to receive weather forecasts is a requirement for most field users.
>
> Regards,
>
> Matt Briggs
>

ZL1LC updated in Equipment on 2020-10-05 14:48

I can 3D print Wire Winders which are ideal for lightweight QRP portable operation.  I have attached a photos of the type that I recommend.  The standard size is 250mm overall but I can make them smaller if required.  The 250mm version weighs approx 30g.  
The best wire to use is the really thin stuff, ( #534) from thewireman.com    He is used to posting to NZ.
Steal a bit of knicker elastic to hold the wire on and you are away.

https://www.youtube.com/watch?v=o8RoYrmr8o8 shows them (about the 8 minute mark,) and a 1:1 balun, which can also be made. 

These are printed in PLA which is fine for portable operation, but probably won't last forever if used in a permanent role.  Some things that I have printed and left outside are still looking great more than a year down the track.  Any random colour except brown or green, so that you can find them at a field deployment site.

Provided you wind on your wire in a figure 8 pattern, the great thing with these winders is that when you come to deploy the wire, you simply secure the loose end to the balun/unun or dipole centre piece, hold the winder through the round hole, and walk away letting the wire wobble off cleanly.

The biggest cost is the postage, which is $6 for an NZ Post bag.  I can get six winders in the bag easily.  These winders are priced at NZ$2.50 each which is basically covering costs.

Also, if you find something else on thingiverse.com that you'd like printed, email me. 

My email is jimreednz@gmail.com

Img 1085 original original

ZL2TUD AKA ZL2XRF posted in Equipment on 2020-06-18 20:41

here in nz it depends on what you require there are many options some of the most expensive are Spectra braid and Vectran braid these have no stretch and a very small cord will be rated somewhere near a ton breaking strain
however uv stabilised polyester offers a very cheap long lasting (usually white with a blue fleck in it). Donaghys use to make rope here but now seem to be in Aus
any yacht chandellry will have a good range. Cookes wire services also carry some ropes

ZL4NVW posted in Equipment on 2020-06-01 09:51

Does anyone know an NZ source for black antenna support rope (2.5 - 4mm, UV stable, dacron or equivalent)?  Maybe dacron is called something else in NZ, but I can't find anyone in NZ selling it.

ZL2TUD posted in Equipment on 2020-06-29 13:11

I bought some of this stuff last week to use as draw cords through a120m length of conduit
`