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Author Topic: DOSY A-SW-4  (Read 1122 times)
KG4RBS
Member

Posts: 8




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« on: January 20, 2018, 05:33:09 PM »

Has any body used a Dosy A-SW-4 antenna switch for ham radio use ?
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W4KVW
Member

Posts: 185




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« Reply #1 on: January 23, 2018, 02:27:54 PM »

If it says DOSY on it I would NOT use it for any band.Cheap garbage & not worth burning up anything I own or use.MFJ is 10 times better quality & that should be a big clue.

Clayton
W4KVW
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K0UA
Member

Posts: 2803




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« Reply #2 on: January 23, 2018, 03:00:28 PM »

The technical answer to your question is no I haven't used one.  But I have a couple of similar quality cheap antenna switches designed for the CB trade.  They are all junk. They have very poor isolation between ports, and poor quality contacts.  I wouldn't trust it. It would be OK for just receivers and antennas, but I would hate to switch even 100 watts with it and not expect a lot of leakage into the other ports and probably a pretty big impedance bump. 
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N7EKU
Member

Posts: 999




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« Reply #3 on: January 23, 2018, 05:12:05 PM »

Hi,

I've seen the inside of one of those and it looked to me like they use the same type wafer switch that is used in MFJ antenna tuners (for selecting the antenna port on the back.)  So I would expect they would be OK for use without an amplifier.  But I would certainly keep an eye on the SWR meter to make sure things don't jump around in use which would indicate poor switch contacts/burning/poor coax connections.

One thing I would check for is riveted coax connectors (some MFJ unit do this too).  These are not reliable and are often done over painted cabinets.  Whenever I saw this type of connection I would drill out the rivets, clean the paint off, and re-attach using star washers and nuts and bolts.

If it's a used unit, you may also want to check the switch positions with an ohmeter on the coax connectors to make sure none of the contacts has been burned up by use with a CB amp and a lousy antenna system.

73,


Mark.
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Mark -- N7EKU/VE3
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