HFU HF Underground
Technical Topics => Equipment => Topic started by: NJQA on December 27, 2019, 1443 UTC
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KA7OEI has a good article on the use of consumer antenna splitters for ham/swl purposes. I wasn’t aware of the problem with using “satellite only” splitters at lower frequencies.
http://ka7oei.blogspot.com/2019/12/using-tv-type-75-ohm-splitters-and-taps.html
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Nice, thanks for the link.
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eBay often has lab grade Mini Circuits brand power combiner/splitters for pennies on the dollar compared to new. https://www.ebay.com/itm/Mini-Circuits-ZSC-2-2-Power-Splitter-2-way-0-002-60-MHz-50-BNC/143482793729?hash=item21683daf01:g:azsAAOSwwJ5eA8Iy
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Finally got off my arse to do some testing of the various splitters on hand. The need for sharing one hf antennae with several rx at the same time has been apparent for ages, but I find it hard to get out of bed some days.
Anyway, I have 3 or more 2 port splits laying about, and one 6 porter. I need 3 ports, but if I employ the 6 porter to get 3 outputs it incurs 6dB loss per port where a 2 porter is down 3dB. With a compromise antennae, one wants to save all the deebees one can. I also learned I don't have enough f connector to X adapters.
speaking of bees
https://www.youtube.com/watch?v=xAhuSDRIDHE
In the case of a 2 port split beiong chosen due the loss, the need to switch between 2 table top sets yet give the sdr access full time arises. So what I did was first test the splits on hand for loss on the ambc band, one was marked v/uhf so I discarded that, the other two were similar in construction but differing in make. On testing, the *Holland Electronics GHS-2 was 3 to 10dB or so less loss than a **GE 2-Way Splitter 5-2500MHz.
Regarding the incurred loss, can't really tell the diff and neither do the rigs, and that is exactly what I wanted from this exercise.
I fed one output of the splitter to a ***AD 4 port antenna switch and that to two hf rigs. So far so good, can run the sdr any time in conjunction with any table top rig desired.
Shoulda done this years ago.
All said, must remember to never tx thru the setup as that will blow away an sdr and prolly a pc too. Another switch with at least 2 ports will allow the hf tx rigs to have the antennae all to themselves when desired.
* http://www.hollandelectronics.com/catalog/catalog.php?product_id=GHS-Series-Digital-CATV-Splitters
** https://www.ebay.com/itm/GE-33526-Pro-Digital-2-way-Coax-Splitter-FREE-SHIPPING-/274115565467?_trksid=p2349526.m4383.l4275.c1#viTabs_0
*** https://www.alphadeltaradio.com/delta-4b.html
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Use an inexpensive wideband LNA in front of the splitter/combiner to offset the port loss. Low noise 15-20dB LNAs go for under $20 on Amazon and eBay. Resist the urge to go bonkers and put in a super high gain one on HF. It'll just increase your noise.