Harvest BC200U - GMRS antenna

[Thorndike113]

I figured I would post this for anyone who decides to spend $100 on a GMRS base antenna. DO NOT GET THIS ANTENNA!!!!

They are sold on Ebay and a few other sites. They claim that they have a low SWR on GMRS (460-470MHz) right out of the box. They do NOT! They are NOT tunable! I was at a loss because the SWR was hardly where I wanted it. I ended up putting a coax RF choke that I made for UHF on the antenna and the best I could do for an SWR was about 1.6:1 on the 462MHz portion of the band and 1.9:1 on the 467MHz portion of the band. There was a significant dip in the SWR giving it a 1:1 match on around 464MHz. I mounted it on the roof and sealed it up tight with the black sealing tape and electrical tape used on commercial setups. 1 week later my SWR shot up to 3:1 across the whole GMRS part of the band and anywhere else on UHF was through the roof. I am running a 45 watt radio on GMRS. The antenna is allegedly rated for 200 watts. I don't know what happened but I double checked and it is nothing on my end. I am running brand new coax and brand new connectors.

I know I should have gone with a Comet antenna but everywhere I checked says there is a GMRS base antenna shortage. No manufacturing of GMRS antennas? I can however find a wealth of Dual Band Ham antennas. I do not want dual band and I certainly DO NOT want HAM radio antennas. I guess I can see where most people are flocking to when it comes to radio. Its GMRS not HAM. I tried to get in contact with the person I purchased this antenna from with no response. At this point, I am seriously thinking of gutting the antenna I have and rebuilding its insides with a proper working GMRS antenna. I fortunately caught the SWR problem early and hopefully didn't fry my $200 radio. Be Aware of these garbage antennas. Very poor design.

I have now mounted my 1/4 wave ground plane antenna, that I built, in its place and it has a good SWR so I know its the Harvest antenna that was the issue.

 

[mmckenna]

There's nothing magical about a "GMRS" antenna, it's just a UHF antenna that will cover that part of the UHF band.

These Chinese antennas that get sold on Amazon and E-Bay are usually cheap junk.

Get a name brand antenna, like a Laird base antenna that will cover that section of the UHF band and you won't have QC issues.

 

[Thorndike113]

I was thinking of going with a Laird but I already had one here that was meant for the GMRS area of the band(460-470) and it was very narrow in its bandwidth. I decided to go with a Comet but no one I could get in contact with had any. They were all out of stock and wouldn't be replenished until late August. I can find plenty of Ham Dual band antennas which really irritates me. I have to scroll through pages of dual band ham and only find 1 or 2 GMRS or something remotely in the GMRS area of an antenna in between all of that. I am going to keep looking but I have enough parts collectively to construct another UHF antenna and really tune it down the way I want it. The only reason I didn't was because I didn't want to shred this new antenna apart. It looks like I will be doing that anyhow haha. I am alright for now. I have the little antenna up there.

 

[mmckenna]

Sounds like you are not looking in the right places.

www.theantennafarm.com Go to their commercial antenna section and find something that covers 460-470MHz. Some of them are really expensive, but there are some reasonably priced antennas there.

www.Tessco.com Again, mostly high end commercial stuff, but you can find similar deals to antenna farm.

www.talleycom.com

There's more, but you need to get away from the ham/hobby/scanner sites. They'll have a very narrow selection of GMRS antennas, as you've discovered.

 

[Thorndike113]

Thank you for the sites. I am finding more of what I need.

 

[mmckenna]

Thank you for the sites. I am finding more of what I need.

Hams are a cheap lot, and many will buy an expensive radio and then cut corners on the antenna system. Many of the ham radio oriented vendors know this and carry very little in the way of quality VHF/UHF antennas. Most of what they do carry are going to be very specific to the ham radio bands, and while they do have a few nice high end antennas, most of their stuff will be the lower tier hobby grade stuff.
Ham radio shops are starting to carry more and more GMRS related gear, since it's gaining some popularity amongst some hobby groups, but unfortunately they still aim towards the lower tier.

On the flip side, you can spend some hideous amounts of money on antennas. I've got repeater sites where the antennas are in the $2000+ each range. You don't need that for GMRS.

Somewhere in the middle is what you need. And there are good options. Laird is a good place to start. Back when I was active on GMRS, I had a Laird UHF commercial antenna that ran around $125.00. It wasn't a super high gain monster antenna, just one good enough to hit the mountain top repeaters in my area, and a realistic simplex range. Fed with good coax, it all worked just fine.

I'm not slamming hams or ham radio shops. I've been a ham longer than I've worked in the industry, and it's a great hobby. Problem is, the 'cheap ham' issue. Makes it difficult to find quality antennas at most ham oriented suppliers. Unfortunately there is way too much Chinese junk out there, and they really don't care what people think of the quality. Enough people will buy it and without reference to a good antenna, they'll assume they have the best antenna in the world. Often you can blow the socks off hams/GMRS users when you set them up with good antennas/feedline.

 

[Thorndike113]

I just actually pulled this antenna apart and when you say cheap, yeah, its pretty cheap. The main radiating element is not bad but its connections to the coil sections are just pinched together, not soldered. I found the problem though. About 3/4 of the way up there is a gap in the radiating element and 2 capacitors in series soldered between the two. They took a piece of foam and glued it around the capacitors as a cheap way to keep them in place. When I looked at it, the foam had gotten kicked around enough to where it wiggled the leads right off of the capacitors. I am seriously thinking of fixing this antenna up to have as a back up. The issue is what is the value of the capacitors used on that? The only thing I could get off of one of the capacitors is '0.5c and under that 1K'. I would assume the other one was the same? Either way, I probably am going to look at maybe getting a directional for the repeaters near me. I am on the fringe of 5 repeaters and they are all in the same direction for the most part.

 

[mmckenna]

That's along the lines of what I've discovered with most of the low tier antennas. it's produced quick and cheap with very little quality control.

You could probably solder the crimped joint and improve reliability.

The capacitors, I think may be a 5pf with 0.25% tolerance, 1000v rated, if the stuff my brain is telling me is correct. Likely both the same.

The directional antenna would probably allow you to run less power, but ruin a lot of simplex coverage.

 

[Thorndike113]

That's what I was thinking. I have a glue gun that will work on the caps and then just solder the joints and get some better foam to place on the radiator and I will be good to go. I had another antenna similar to this one and it used the same quality metal for the element. the difference was that it was soldered on the joints, not pinched together.

As for the directional antenna, I will have to run it with an omni. The bad part is where I live. I live in a hole and repeaters 13 miles away dont come in reliably. There is one repeater 66 miles from me that I get into beautifully. Doing it that will allow me to tune both antennas down with a good match. For some reason I cant get any antenna I used to have a wide bandwidth to where it will cover from 462-468 with 1.5:1 or less. Right now, the 1/4 wave I built does, but with around a 1.6:1 match. I am sure I will get it squared away eventually. As long as I do before winter comes. Maine winters are usually long.

 

[mmckenna]

I found Tram/Browning pre-terminated NMO mounts to have a similar "smash it with a pair of pliers" approach to making good electrical contacts.

A 1/4 wave naturally is a very broad banded antenna, and should give you a pretty flat SWR curve across a big slice of spectrum. You high SWR may be due to the vertical element length, or it could be due to the slope of the ground radials.

As for the higher gain antennas, they get narrower in bandwidth, but they should still give you decent performance across the 462-468MHz range.

 

[Thorndike113]

I fixed the Harvest antenna

Soldered up all the joints where all the coils come together, Removed all 3 capacitors, and trimmed the whole radiating part down, put the antenna up with a coax choke on it and the SWR is below 1.4:1. It still operates the way it did before with a slight bit more coverage but the SWR's are down. I still would NOT recommend this antenna. I am going to be getting something better but this works for now. I live in a hole with 3 hills all around me, so I think its doing pretty good despite the circumstances.

 

[mmckenna]

Nice job, always rewarding to fix something rather than replace it. Old Skool…..