Jointenna connector problem

#1
Today I installed a channel 9 Jointenna that I had purchased from Amazon.com. When I attempted to tighten the F connector, it turned on the circuit board and broke the connection to the capacitor. When taken out of the case, I found that the F connector was not properly soldered to the circuit board. The F connector is plated with a metal that solder does not adhere to. I had to scrape off some plating before the solder would properly wet the connector.

The F connector has a flat side and the circuit board is punched with a D shaped hole; but the bakelite is too weak to help much.

Next I looked inside my 20 year old channel 13 Jointenna. The F connectors have the same problem with solder.

In addition, I have found that a HLSJ has less loss than a low-band Jointenna.

Due to these problems and the uncertain availability, I am going to stop recommending Jointennas.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#2
Dont the JoinTennas have a steeper more targeted filter slope? So that you can presumably use another antenna within the VHF band? An HLSJ doesnt allow integrating VHF High with VHF High single channel yagis....or a single channel yagi to a VHF broadband yagi. And so on and so forth.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#3
re: Jointenna (made in Taiwan)

Tower Guy: THANK YOU FOR THE HEADS UP !!! :hail:


I just took an unused Jointenna-13 out of its case and I see what you are talking about -- in fact, TWO fittings on this one aren't even finger tight!

I checked two other Jointennas and I found four more loose fittings. Whoever assembled them did not tighten the nuts. Next, because of the design of the fittings, there isn't any way to hold the fittings from behind to tighten them.

There is a splash of solder on the copper "circuit board" and there was an attempt to solder the shield side of the connectors to the board, but they are cold joints and those two fittings rock back and forth in their holes.

* Tower Guy, are you sure the circuit boards are punched with 'D' shaped holes (as they should be)? None of the three Jointennas here have their fittings clocked in the same directions, so I suspect they are round holes.

I am going to put a short length of rubber hose over the threaded portion of the fittings, grab them with plier and then tighten the nuts. Next, I'll use my Dremel to grind away the plating on the board side, and try to solder them.

Another thing. They have two holes in the top of the plastic case to pass long mounting screws thru that would allow gallons of rain to enter. If I use one of them, I will seal those holes as well as the junction between the circuit board and the case with RTV.

I agree with you, I cannot recommend them. Photos below.
Jim
 

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EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#4
The problem, it seems to me, is that nothing else is available on the market. And since these are discontinued....when they are gone, people are just SOL, as far as that solution goes, without knowing a ham guru who can fashion a bandpass filter, or paying big bucks to Tin Lee.
 

Piggie

Super Moderator
#5
Speaking of which, I was thinking about buying one to join in a Ch9 antenna to point at Gainesville to my stack that points at Jax that has a 7,10, 13. The antennas would be 90 degrees to each other (one about north and one about west).

Of all the Jacksonville channels I could stand to loose it would ch10, though I would rather not as they have the only local weather.

What is possible with a join tenna, as far as my situation and what loss would I see on both antennas? I know what the device is but never dug in and here looks like a thread to ask the question.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#6
Jointenna update

I was able to tighten the nuts on the fittings by using an adjustable wrench on the flat side of the threaded portion of the fittings and an open-end 7/16" wrench on the nuts.

I used a small carbide cutter in my Dremel and ground away areas on the backsides of the fittings and successfully soldered them to the circuit board. I used a 25 watt iron, but the copper board carried away the heat very quickly, so I recommend a 40 watt iron. I wish I had one.
Jim
 

Tower Guy

DTVUSA Member
#7
Tower Guy, are you sure the circuit boards are punched with 'D' shaped holes (as they should be)? None of the three Jointennas here have their fittings clocked in the same directions, so I suspect they are round holes.
Well, I never completely removed the other F connectors, so the hole on the failed end could have been round even before I thought I rounded it. But the two remaining flat spots did line up on my channel 9 Jointenna.

The 20 year old channel 13 Jointenna had all three flats in the same direction, but I didn't remove actually them from the circuit board.
 

re_nelson

DTVUSA Member
#11
[...] I was thinking about buying one to join in a Ch9 antenna to point at Gainesville to my stack that points at Jax that has a 7,10, 13. The antennas would be 90 degrees to each other (one about north and one about west).

Of all the Jacksonville channels I could stand to loose it would ch10, though I would rather not as they have the only local weather.

What is possible with a join tenna, as far as my situation and what loss would I see on both antennas? I know what the device is but never dug in and here looks like a thread to ask the question.
First the requisite TV Fool info for background:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=c7232ac75b38a0

Let me jump into this thread since I now have experience with a ``Channel Master JoinTenna Model 0582 Channel 12 Combiner''. After reading Tower Guy's message upthread, I was *VERY* careful when attaching the RG-6 to the F-connectors realizing how fragile they were. So I'm sure I didn't break anything.

The Channel 12 side is connected to a YA-1713 armed properly at KXII/12 to the north. Excellent! It hits fullscale at 97% on a Toshiba ATSC tuner.

Aimed south is homebrew dipole with a reflector I built that works very well for WFAA/8, KFWD/52 (RF-9) and KTVT/11, all of which measure between 92-97% on that tuner. That antenna is connected to the All Channel input of the JoinTenna.

I am VERY disappointed by the JoinTenna and have since identified the problem beyond all doubt. KTVT/11 dropped from an invariant 97% to a constantly oscillating 37-52%. The other VHFs to the south, WFAA/8 and KFWD/52, were not adversely impacted.

You probably see what's happening. The strong KTVT/11 signal produces enough on the backend of the YA-1713 that it mixes with the frontside of the homebrew dipole. Note that KTVT/11 on RF-11 is not shown on TV Fool due to the CP for RF-19. Both facilities are active and transmit from the same Cedar Hill, TX site.

The Channel 12 JoinTenna does a fine job of filtering out channel 12 from channels 8 and 9 but FAILS utterly to deal with adjacent channel 11.

The proof came from disconnecting the Channel 12 side and watching KTVT/11 return back to iits steady 97% reading. And conversely, disconnecting the All Channel side, the Channel 12 side yielded the 97% reading for KXII/12 and 50-52% from the backend for KTVT/11. Both WFAA/8 and KFWD were 0 as expected. The hope was that Channel 12-specific JoinTenna would have also filtered out KTVT/11 as well. Instead of sharp notch filter, it behaves more like a gentle curve.

On the bright side, there was no loss evident (except where I WANTED there to be). :)
 
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#12
Bob,

Jointennas usually take out the channels adjacent to the inserted channel, so your observations would be considered normal.

It just isn't possible to have the filters sharp enough to not affect the adjacent channels
 

re_nelson

DTVUSA Member
#13
Jointennas usually take out the channels adjacent to the inserted channel, so your observations would be considered normal.

It just isn't possible to have the filters sharp enough to not affect the adjacent channels
Thanks for that information. At least I know now that I didn't botch it! :) Instead my expectations were incorrect.

My reception issue was ultimately resolved with a ClearStream C5. I'll explain all about it in the other thread devoted to that quite remarkable smallish antenna.
 
#14
Thanks for that information. At least I know now that I didn't botch it! :) Instead my expectations were incorrect.

My reception issue was ultimately resolved with a ClearStream C5. I'll explain all about it in the other thread devoted to that quite remarkable smallish antenna.
That's good news. Look forward to seeing your report!
 
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