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SWR Meters and built in ATU’s (3 replies)

(unknown)
9 months ago
(unknown) 9 months ago

Hello

I see there are some transceivers that have an ATU built in…

For example the Kenwood TS590 has a built in ATU, does this mean it also has a built in SWR Meter? or do I still need a separate one of those regardless. If so I see there are different models for different frequencies and as I am having to wait a while before I transmit on HF…

I will need a 70cm/2m SWR Meter for my handhelds now, which are Baofeng UV-5R’s, so has anyone got any recommendations, is it a waste getting one that does HF too because I’m definitely getting a HF unit with a built in ATU or do these generally not have SWR Meters built in as well. Logic tells me that if it’s got an ATU it must have a SWR or does it, it’s all a bit confusing. 

Anyway I know I need a SWR meter for now though as I might build a flower pot antenna as shown in this forum somewhere.

Also are these VNA’s any good I see you can get them cheap from China and it says they can do SWR and they are around £30 or less.

ok thanks in advance

Shane

 

 

 

 

G1BED
6 months ago
G1BED 6 months ago
  1. VNAs: recommended as they're great for aerial checking and a million and one other things! I use an SAA2N with the larger screen and N-type connectors which is a lot easier than the normal SMA jobs. Don't go for the cheapest chinese clone though.
  2. SWR meter: if you're using a radio with built-in ATU then you'd have to rely on what the radio shows but I'm always wary about the accuracy of those indicators. My preference is for a separate external meter and ATU (I've got one ATU which will tune anything into a piece of wet string! Most built-in ATUs will only handle a limited mismatch). Again, a decent cross needle meter is best (mine has inputs for HF and V/UHF).
Peter M0PWX (2E0PWX)
6 months ago

yep, VNA's are great, but if you get one remember to calibrate it each time you use it (takes 1-2 minutes) and look at getting the book "nano VNA's explained" its an RSGB book about £12-£15 but shows you how to set them up and use them for filter alignment, tuning stubs, checking crystals and much more

if the radio has an ATU it has an SWR bridge in there to allow the ATU to work, but weather you can see the SWR on the radio depends on the model, my FT991a the ATU can only cope with a 3:1 mismatch or lower so you have to get the antenna rough tuned before the radio ATU will work, my Xiegu G90 and X6100's will tune virtually anything, but then over 3:1 you are dumping a fair bit of the signal into the ATU inductors as heat so the closer you can get the antenna to resonance the less heat the ATU has to dump

my 2 Xiegu transceivers also have a reasonable SWR sweep display so you can see where the antenna is tuned so it makes tuning antenna a lot easier, if the lowest SWR is below where you want it you shorten the antenna, if its above you lengthen the antenna

as to SWR meters 

cross needle models don't need calibrating

single needle meters you have to calibrate by setting full scale  then do the reading

73

Peter

M0PWX

(Not Pete M0PSX who runs the site)

M7FFI
4 months ago
M7FFI 4 months ago

I do have a external atu and swr meter for my ftdx1200 but I prefer to tune my antennas with a RigExpert antenna analyser to get it the right length for the frequency you intend working done correctly you should be able to get most antennas down to under 2:1 swr even before you connect it to the radio then the internal tuner will happily work to the best efficiency to give a real good match, I believe that is best for me others may disagree everyone has there own way of doing it most modern transceivers have a decent enough built in unit to handle this, however older ones may not but the same thing still apply that if you tune the antenna properly first its not always a big deal I've got antennas down to almost a perfect match on the desired frequency prior to connecting to the radio imo a good antenna analyser is the best piece of equipment you will buy and you can also test the feed line etc, I would also recommend if you are going to buy a HF rig in the future go either Yaesu, Kenwood, or Icom they are among some of the best value for money rigs out there imo again others may say different maybe! also I found the less connections in your line up the better as joints can be week points, if you do really find the need for a external tuner it may be even better going for a remote tuner connected to the antenna feed point just a thought they can be a excellent option I would spend some time doing plenty of research as its a mine field for sure and different for everyones situations.

Atb hope I have been at least a bit helpful and good luck with your radio comms Alf.

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