A Nearly Universal Whip Adapter for the FT-817
Why is this man smiling? Because he's finished his project, and it works.
This FT-817 antenna bracket will accept 3/8-24 stud mount antennas, as well as BNC mount antennas and UHF connector antennas with a quick change of hardware. This lets you use just about any type of whip antennas you have on your handheld FT-817.
As will be discussed below, the ability to double your whip length can add as much as 6 dB to your signal, not bad for a few bucks of metal and an hour's work. And it doesn't require batteries!!😎😎
Executive Summary
This blog entry will describe in the most annoying detail:
1) the origin of the FT-817 whip project;
2) some build hints for an improved Rev. 1 antenna mounting bracket, including how to use it with 3/8-24 stud mount, BNC mount and UHF mount antennas;
3) why (antenna) size matters; and
4) a brief review of the MFJ-1898, which I've settled on as the current best whip for me.
Why a Whip Bracket?
Because sometimes, it's the best you can do.
I started using the FT-817 with a whip from the very beginning.
As a business traveler, the FT-817 held a lot of appeal. Soon after its introduction, Waters and Staton introduced the ATX all-band whip. I was working for BP at the time, and the next trip to London I had an ATX delivered to my hotel.
Two days later, laid up in London over the weekend, I was in the parking lot at Duxford working all manner of Europeans with the ATX plugged into the front BNC socket of the FT-817. I was hooked.
But a few months later, I was replacing the front BNC socket on the FT-817.
I knew at the time that with frequent field use, the ATX was really too much of a load for the FT-817, but nevertheless had to prove it to myself. After that, I began using vice grip mounts and mobile mounts on rental cars to hold up the ATX. As the mounts got bigger, so did the antennas, and the ERP.
Fast forward to 2015. Retired, we began river cruising. Many boats didn't want you to have radios on board, and definitely not out on the deck. Many resorts feel the same way. And I'd moved on from the ATX to a Buddistick by that time.
A couple beers later, 2 days before the next river cruise, I decided that if I could mount a bracket on the 817 that would support some version of the Buddistick, I could smuggle the radio and antenna on and off the boat in daypack at every stop, set up on a bench or a beach with a drag wire, and operate almost anywhere.
Also, because I'm cheap, building the adapter meant not trying to procure yet another portable antenna, but simply using what I already had on hand. You could use a Hamstick for example, if you didn't have to fit it into something small to smuggle it on and off a boat.
This was the result.
Radio operations on that cruise were amazing. Resting the bottom of the 817 on your thigh and holding the radio in your left hand leaves your right hand free for operating a paddle or mic. You can stand and hold it up if you like - but it's a bit more work than I prefer on vacation.
That blurry picture is the only remaining documentation of the Buddistick and FT-817 combo that let me operate from benches, the quay or in parks pretty much whenever I wanted. No throwing wires (except a 13 foot drag wire), setting up, tearing down, or constantly looking over my shoulder for the local gendarmes. Again, I was hooked.
There wasn't much imagination or craftsmanship involved in that Rev.0 configuration. I took a piece of an old aluminum panel, cut a strip the width of the 817, drilled 4 tiny holes where the cabinet mount screws fit on the side and a half inch hole near the end, struggled to bend the thick bracket to a 90 degree angle, scoured the junk box for longer but not too much longer screws to fit the thick bracket to the radio (harder than you think, see below), and it was good to go.
The antenna was a 12 inch Buddistick bottom section, a standard coil, and a standard whip. This worked well on 10 -30 meters - but didn't quite resonate on 40 - and saw service until 2019, when operating on Guernsey in 35 knot winds convinced me I needed an antenna configuration with less wind resistance.
Should have seen that coming. But by going to the smaller Buddipole 10-20 meter coil, and switching from a standard whip to a much narrower Buddipole Featherweight whip, the wind resistance is substantially less.
This is important at all those exotic locations like GU and ZF, where wind at the shore is a fact of life.....so went to this configuration.
I'd tried to make the adjustments easier using the coil slider developed by Linus, LY2H. Bing Videos
A very slick bit of innovation, but I had problems with sometime intermittent coil contact that I couldn't solve after a bit of struggle, so I continued to look for a better antenna.
My minimum antenna requirements were reliable coil contacts, operation from 10 thru at least 30 meters with easy frequency adjustment, and commercial availability for people that don't like to build. This led me to try the relatively new MFJ-1898.
And I thought the bracket could be better. The old bracket had thick metal that was hard to work, was odd-sized, protruded above the top of the FT-817, and just generally was a PITA to build.
This led to the Bracket, Rev.1.
Building An Improved Rev.1 Bracket
The original bracket is on the left, and the current Rev.1 bracket is on the right. While I'm as fond of overbuilding any field accessory as the next guy, I decided that Rev.1, is, as they say about the horsepower of a Rolls Royce, simply "adequate."
Rev. 1 differs from the original in several ways.
1) Rev.1 is shorter, with the stud adapter located down the side of the radio about an inch to keep the adapter top even with the protrusions on the face of the radio.
2) Rev. 1 is thinner metal, allowing the use of the original cabinet screws for securing the bracket. While the original bracket was 0.12 inches thick, Rev.1 is only about 0.06 inches thick. The aggravation of finding longer M2.6 screws is not to be underestimated.
3) Rev. 1 is narrower. Rather than using a custom-cut piece of metal the width of the 817, Rev. 1 is built from narrower 1 inch wide strap of aluminum bar stock, a common size available at local hardware stores.
4) The UHF to 3/8-24 stud mount adapter - originally borrowed from a CB mirror mount - has been replaced with a 3/8-24 bolt and a 3/8-24 female to female coupler to simplify the mount;
5) While it didn't require a structural change, the bracket is now usable with BNC, UHF, or 3/8-24 hardware antennas by swapping the connectors mounted to the bracket; and
6) If you look at the RG-8X jumper, you'll see that a blue bullet connector was added to make it easy to attach the 13 foot drag wire I usually use with the pedestrian mobile handheld whip configurations.
Building the bracket is much quicker than talking about it.
Step 1
Cut off the length of the bar stock you want to use - I used about 10 inches.
Step 2
i) Mark your bracket stock with the locations of the 4 cabinet screws on the left side of the radio;
ii) mark the line where you want to bend the bracket into the horizontal whip mounting portion and the vertical radio mounting portion;
iii) mark the point of the horizonal portion where the 1/2 inch hole will be drilled for the insulators; and
iv) mark the end of the horizontal portion that will be trimmed AFTER the bracket is drilled and bent.
A nice trick for marking small holes before drilling is to remove the cabinet screws, cut a piece of painters tape to the size of the aluminum bar (see below), then
Step 3
Bend the bracket. Because the bar stock is relatively thin, you can do this in a small sheet metal brake, or between a couple pieces of wood in a vice. Check with YouTube if you need direction on easy metal bending.
You waited to cut the bracket to length after the hole is drilled and the bracket bent, as this lets you have a longer length of stock beyond the large hole when bending - trying to bend a 1 inch piece is much harder than a 3 inch piece, especially if you don't have a sheet metal brake.
When you've bent the bracket, trim off the excess. I use a cutting wheel on a Dreml tool.
Step 4
Mount the bolt, insulators and coupler to the bracket.
Note that there is an insulator on the bottom of the bracket and one on the top. If both insulators have a smaller thicker section for mounting through the hole, only one will fit in the hole because of the thinness of the metal.
No problem, just flip the other insulator so that the smaller diameter end part is not trying to fit into the hole. Once the two insulators are fitted over the bolt and the bracket, add the ring terminal of the feedline over the bolt, and secure the bolt with the coupler.
Step 5 - Mount the bracket to the radio using the existing screws.
Some people have expressed skepticism as to the ability of the cabinet screws to hold the bracket. I can only say several years of operation suggests otherwise.
If you want, you can use longer screws, but you MUST MAKE SURE THE LONGER SCREWS DON'T EXTEND TOO FAR INTO THE INNARDS OF THE RADIO. For this reason, my rule of thumb for brackets like this is don't use a screw that's longer than the original by more than the thickness of the bracket. Should be obvious, but in the heat of battle, mistakes are possible, don't ask me how I know this.
But What About BNC and UHF Connector Antennas?
No problem.
Accommodating a BNC antenna like an AX-1, MFJ single bander, or the old ATX was almost an afterthought but a happy one.
Same goes for UHF-base connector antennas. Admittedly these are less common, but my Outbacker Joey is one, as are some Yaesu and Icom antennas.
The picture below shows hardware configurations for BNC and UHF connector antennas.
On the left, the UHF set up requires inverting a UHF to 3/8-24 stud connector as used in mirror mounts. By turning the connector upside down, the 3/8-24 stud sticks out the bottom and can be secured with a 3/8-24 nut. You can mount the coax ring connector top or bottom so long as it stays insulated. The UHF connector sticks up to receive the antenna.
The BNC set-up is easier yet, as no insulation is required. That is just a BNC bulkhead connector of sufficient diameter to allow mounting through the existing 1/2 inch hole. Then just use a BNC to BNC jumper.
Why a bracket for a BNC antenna? Remember when I mentioned reworking the FT-817 front BNC socket? Taking the stress off the radio's antenna connector is well worth the trouble if you never use the bracket for anything other than BNC-based antennas.
I was asked for more detail about the stud hardware used for these different mounting configurations. This should do it.
Finally, why size matters
It's axiomatic that longer short verticals are more efficient than shorter short verticals, but does having a strong whip mounting bracket really make that much difference?
I'll let you decide. What we know about this, at the most basic level, is that the equation that determines antenna radiation resistance tells us that radiation resistance changes with the square of antenna length.
Simply put, all other things being equal, and with a lossy ground that we're sure to have, doubling the antenna length quadruples efficiency.
In practice, suppose you have a 16 foot tall 20 meter antenna. If you go to a half size 8 foot antenna, your efficiency will likely decrease by 2 squared, or 4. Cut that in half to 4 feet and the efficiency decreases again by a factor of four.
We know a change in power level of four times is 6 dBs. So you can expect that an 8 foot 20 meter antenna will be 6 dB down from a 16 footer. But it will be 6 dB louder than the four footer.
All this is just theory, and there will be practical differences in construction that will figure into the loss equation, but among comparable, well-constructed antennas, this is the expected result. And I can confirm anecdotally that an 8 foot antenna works much better than a 4 footer.
So if I go from a BNC-supported 4 foot antenna to a bracket supported 8 foot antenna, I'm probably looking at 6 dB of difference.
For me that's a lot. Having a bracket means I can use my 7 foot Buddistick (or longer with a longer whip) or an 8-9 foot MFJ-1898, again maybe 6 dBs better.
I'll take it, it's little work for the gain (no pun intended....).
The set up is a little heavier than I'd like, especially with the MFJ-1898. Yet I've comfortably used it in hand-held mode.
It's easy to rest the radio case on a tabletop or fence rail to make operating easier. Whether you find it comfortable to use will depend on the size of your hand, and arm and grip strength. The shape of the FT-817 isn't a great ergonomic match for hand-holding, and this gets worse with progressively larger and heavier antennas. A decent glove, with a grippy surface, can go a long way toward making handheld operation more fun.
The MFJ-1898
Having shored up the antenna bracket situation, I now can consider using something relatively heavy like the MFJ-1898. This is a quick adjust multi-band slider coil antenna that just cries out for use on a no antenna tuner radio like the FT-817.
More on that in a few days.
The Fine Print
As author Jean Shephard W9QWN once wrote, "You'll shoot your eye out!!!"
Probably not, but be careful.
This is a description of what I've done. You need to make your own decisions about suitability and safety. Observe RF exposure guidelines, stay a safe distance from other people and pets, and objects, especially electrified ones. And watch out for yourself whether building or operating, Keep ham radio fun.
72 Scott ka9p/zf2sc
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