Swr meter for UHF/VFH?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by DOCD, Feb 22, 2015.

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  1. DOCD

    DOCD QRZ Member

    I just passed my exam and my first order of business is to set up a 2m/70cm mobile and external antenna in my house. I've been searching for a SWR meter and the reviews are terrible for them. Many say there is just no such thing as an accurate VHF/UHF SWR meter. Are there any accurate VHF / UHF SWR meters or do we just trust the antenna makers?

    Any antenna or coax recommendations? The coax run I'd probably going to be 40 - 60 feet. One of the questions on the tech exam says you need to use n-type connectors. That's my plan but I thought I'd check it out with the experts and verify that's what I need. I'm looking to order everything (radio, antenna, coax, connectors, etc) tomorrow.

    Thanks!
    Doc
     
  2. K4ETN

    K4ETN Ham Member QRZ Page

    Many of the available swr meters are highly inaccurate at VHF and UHF frequencies. For that reason you should think about investing in a Bird Model 43.

    The 43 is the industry standard and uses frequency based "Slugs" of different power levels and freq range. Although not cheap, it is a lifetime investment.

    On antennas, the higher the gain factor the narrower the acceptable bandwidth of operation. And where your swr will be acceptable is in the middle of the band range. A quarter wave antenna is by its very design, wide banded. And your swr will stay within acceptable limits over a broader range of frequencies.

    One of the best dual band quarter wave base antennas out there is made by Arrow Antenna. They are extremely well made, require no tuning and last for years under adverse conditions. Either direct from the manufacturer or through Ham Radio Outlet. Here is the direct link:
    http://www.arrowantennas.com/gp/gp146.html

    On the subject of N type connectors, yes they are by far the best at higher freqs. But most dual band radios use the standard PL-259 female (SO-239). At the power levels you will be running it is a non issue. They will loosen up over time, so make sure they are seated properly and just snug them down a little with a pair of slip joint pliers.

    Use good quality connectors. Amphenol or silver plated connectors are easier to solder unlike the cheap nickel plated ones. For a couple of bucks more, you'll be happy you did. On your outdoor connections, use quality electrical tape, such as 3M 33 and coax seal then followed by another couple of wraps of tape. Learning to properly weatherproof your connections is very important.

    I will now put on my flame proof suit for this one.
    Coax- There are many choices out there. The longer your run the more loss in decibels you will have. 3db of loss over 100 feet is half your power to the antenna.

    I stay away from RG-8, RG8X, 9913 and RG-58 of any type unless it's a jumper of 2 ft or less. For general 2m and 440 home antenna systems the TImes Microwave LMR-400 is by far the best choice with lower loss and better shielding than any of the others. There are some companies that make a comparable type coax, such as RFS, Shireen. Buy the best coax you can afford.

    The bottom line is to do this once and walk away, being able to enjoy your new radio and it's performance.

    Hope this has helped.
     
  3. KD4UPL

    KD4UPL Ham Member QRZ Page

    You can't go wrong with a Bird for sure.
    I use a Yaesu VHF/UHF meter. I don't know how accurate it is but it gets the job done. If you just tunning up a mobile antenna you just going for minimum SWR anyway. Who cares if it's 1.6 and the meter reads 1.3? If you were doing lab experiments or tweaking a home built antenna design then maybe super accuracy would matter.
     
  4. K8ERV

    K8ERV Ham Member QRZ Page

    Micronta SWR_crop.jpg This works well for me. The object is to go for the lowest reading. The exact higher value may not be too important.

    TOM K8ERV Montrose Colo
     
  5. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    Actually, for weatherproofing, the very cheap black electrical tape works very well. After a few weeks, in the sun, it congeals into a weatherproof "mass" that has to be cut from the connector to remove. Decibel Products, which was, for years, a very major manufacturer of commercial two-way antennas, used to put a roll of this tape in with every base station antenna.

    I have removed this "mass" from feed lines that have been "up" for decades and, when the mass is cut from the connectors, they look like the day they were installed.

    There are a few wattmeters that are as good as the Bird 43, even better, like the Bird 4304 and the Telewave 44A. However, those meters are more expensive than the Bird 43. The Bird 43 has been around for decades and they are the standard wattmeter of commercial two-way radio.

    As for feed lines: Used 50-ohm cable, like Heliax and similar products, with corrugated shields, can be found for very good prices. These types of cable hold up very well for decades. Also, "hard line", which generally is 75-ohm, that is used by cable television companies, is often available for low prices, and even for free, brand new. Cable companies often basically "throw away" lengths under around 200-feet.

    One can also build their own SWR bridge for VHF/UHF. They are not that hard to construct. There are suitable projects available.

    I have included a scan of 1 easy to construct VHF SWR bridge. The housing can be of considerably different sizes including aluminum mini-boxes.

    vhf swr-1.jpeg vhf swr-2.jpeg

    Glen, K9STH
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Birds and their equivalents are pretty accurate when the detector elements are new or recently calibrated. But the main advantage of that type meter isn't so much 'accuracy' as it is having zero insertion loss and great versatility. The Bird 43 system, which is an old design that's been around about six or seven decades and still works fine, allows you to measure forward and reflected power from below 1 MHz to above 3000 MHz, at power levels from less than 1W to about 5000W, all using the same meter and just changing plug-in detector elements. That's the primary reason to own something like this.

    By design, it also has virtually zero insertion loss even at UHF and SHF, which only similar construction bridges can have.

    However, the Bird 43 system does not actually indicate SWR at all. It indicates forward power, and reflected power, and you have to calculate SWR based on those readings. If SWR is low, you generally need at least two detector elements to accurately measure the reflected power, since using the forward power element the reflected reading can be so far downscale you cannot accurately resolve what it is.

    For occasional use like tuning an antenna and then leaving it alone, many less expensive meters, whether they're really accurate or not, should be fine. It doesn't really matter if SWR is 1.1 or 1.3, as long as you tune it for 'minimum.'

    I don't leave a meter in line all the time unless I'm using equipment that requires tuning, so the meter assists with the tuning. If you're putting together a 2m/70cm FM setup, you really only need to measure SWR once, when you set up the antenna. After that, there's no real reason to keep looking at it. As such, you might be able to borrow a good meter just for one day, use it, and then return it.
     
  7. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    If you can afford it, you can get a BIRD directional wattmeter. These are very accurate...but you pay the price.
     
  8. KB0MNM

    KB0MNM Ham Member QRZ Page

    Hey Doc ( That is one of my nicknames, too, on account of my last name )-
    Consider the Telewave wattmeter if money is not a big deal. It is made by the same Bird company and has a minor correction graph for the business of covering such a large range ( to approx. 900 Mhz., I believe ). Also, you mentioned type N connectors- good idea- so how about Times Microwave LMR line of coax ( better for UHF needs ). Another suggestion- GP3 base station antenna ( Comet or Diamond if memory serves )- has the type "N" if ordered that way and is very sturdy. If you want to use a rotor, then a 3/6 element ( 3 on VHF ) yagi from Antenna Specialists would be an economical option at under $200. For remote repeater contacts, the Yagi and rotor would be better.
    73 de KB0MNM jkliv01@comcast.net ( not just jkliv@ any more- moved QTH )
     
  9. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Is Telewave made by Bird?? I had no idea! Well, even an OF can learn sumpin' occasionally. "_
     
  10. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

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