Thursday, 20 April 2017

More portable tests

Had one evening to do final tests. I think all the radio gear is still too heavy. I use 8 Mtr Aircell7 coax and a small piece of 3 Mtr RG58 with a home made window "throughput". The Aircell is heavier then RG58 but has considerable less loss, it is a choice. I still think the VOX modem can be build smaller and another heavy weight is the SWR meter. I don't put the antennas in the backpack as it will travel in a corner of the cars trunk.





Anyway, had a few hours to test the superantenna MP-1 for the upcoming portable event. This antenna is small and doesn't weight much. It is not too tall so it will not be visible by others when standing on a side of a house. Didn't change much on the antenna but last year it felt on the ground and I had to repair the telescopic part again which is in my opinion the weakest part of the whole antenna. I decided to make a spare telescope antenna and take it with me...however I didn't have the time to actually test this "new" homemade part.



I chose the 40m band and build the antenna in the garden just beneath my shack. Complete setup takes about 5 minutes. It includes the tripod, antenna and the 4 wire radials. The tripod is held firmly on the ground by extra guylines and tent pegs. This tripod is not suitable for use on concrete or rocky soil as it is just too light and the antenna and tripod will be blown over by the wind.




After some tweaking the SWR was almost perfect. Unfortenately on 40m bandwidth with SWR beneath 1:2 is only 100 KHz. Doesn't matter for me, tweaking is not difficult.

Great, ready to go.....forgot something....





Had to do some tests of course...some PSK31/63 tests didn't work. Don't know if it is the modulation on FLdigi or just the QRM on the receiving stations site. However JTDX did a great job! It does surprisingly well on my old Windows XP laptop.


First station received was JF3VAX from Japan. Both antenna and software still are amazing!
Made only one QSO with RN3ZRD from european russia and got a -21dB report. I was TXing with 5W.


8 comments:

  1. Hi Bas, using about 10 meter coax the loss is marginal, could be something like 0,4 Db between the RG-58 and Aircell 7. And loss is a length multiplier, so 3 db loss at 100 meter is 1,5 db loss at 50 meter and 0,75 db loss at 25 meter. So using 10 meter never could be a really high loss. A cheap connector converter might give you more loss than the difference between any coax at 10 meter length. 73 de Kees PE2KM

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    1. Not agree with you Kees. In theory it doesn't matter but I Remember long time ago I Used 10m rg58. when changed to rg213 it was a huge difference. 73, Bas

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    2. I guess there was another issue going on like bad coax or bad plugs. Also factors like SWR is huge as the capacity of the used cable can be to high or to low for that given frequency and SWR. Assuming a antenna is in resonance the use of 10 meter coax, be it RG58 or RG213 is at max 0,8 dB difference at 30 Mhz and almost nil at 4 MHz. So, with a compromise antenna like the MP1 there could be different results on different bands with 2 pieces of coax and it might happen that the RG58 is better on some bands and the RG213 on others... 73, Kees

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  2. Hoi Bas, goed dat je je uitrusting test. Bijna iedere week ben ik Pedestrian Mobile actief in de natuurgebieden langs de Rijn. Hond mee, rugzak met apparatuur etc. En toch veranderde in het begin steeds wat aan de inhoud. Maar aldoende leerde ik. Tegenwoordig heb ik lijstjes met wat ik moet nemen voor vakantie, mini velddag, portable in de natuur en pedestrian mobile wandelend door de bossen met de hond. Zo'n lijstje is ideaal want er is niets erger dan wat vergeten te hebben. Succes met de voorbereidingen en testen. 7 3 Hans, PE1BVQ

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  3. Nog een tip om omvallen van je fotostatief/MP-1 te voorkomen. Maak een lus van ti-rips onder bij de antenne voet. Buig een haak, hang hem in de lus en hang hier je rugzak aan. Door het gewicht blijft de driepoot stevig staan. Zeker als je nog een fles drank in je rugzak heb zitten hi. Succes!

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    1. Goede tip hans. Bedankt. Ik schrijf geen lange replies want tikken op telefoon gaat erg lastig. 73, Bas

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    2. Goede tip hans. Bedankt. Ik schrijf geen lange replies want tikken op telefoon gaat erg lastig. 73, Bas

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    3. Ja, maar als je dan 2 dezelfde korte mailtjes tikt had je ook wel 1 wat langere kunnen doen... HI...

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Thanks for your comment. Bedankt voor je reactie. 73, Bas