Remote aerial for Kenwood TK-3310?

[trebor]

I do believe that the rubber antennas that come with the radios are GPI, can't see it any other way, even with the alloy chassis.

I read somewhere that the user of the handheld radio is the groundplane.

When people say that it's illegal (i.e. against OFCOM regs to use an external antenna) they aren't correct.

Correct, it is the contruction regs that don't allow the manufacturers to produce them with removable antennas. In the early days of the radios I believe the regs also didn't allow modification after construction but this was changed a few years ago.

Regrettably this is incorrect. Whip antennas radiate their power in an approximate doughnut shape. Not with a hole in the middle but certainly dimples... So with a radio on it's side under the seat and inline with the axis of the bike, you might get reasonable Tx to each side, fore and aft it would be poor. Similarly, across the axis fore and aft would be reasonable, side to side poor. Added to which you have lots of gubbins in the way and are iradiating you testies, prostate etc...

+1
Though increasing the power will increase the range in all directions, especially due to the signal being reflected, but the best solution is to get the antenna mounted vertically.

Regarding the parts you need to modify the radio, I think Bumpkin's link in an earlier message leads you to the parts, but just in case it doesn't look at this post.

What is important is to use as few connectors in the antenna set up as you can. Each connector has the potential to lose approx 0.5 dB of power. In your post above (post #18) you have 4 connections and, therefore, the potential to lose up to 2 dB in power (a 3dB power loss represents half the power). You will get more radiated power, and therefore more range if you can reduce the connectors, and this can mean a lot with the low power of PMR radios. On my set-up I have just one connector, at the radio, the coax is connected direct to the antenna.

The antenna I used is the 0058 on this page (or click here for full details). Renair will cut the antenna to the correct length to optimise it for the PMR band, they will fit the required length of coax you need, and whatever connector you need for the radio (SMA if you use the connections mentioned in the link above).

This arrangement increased the range of my radio broadcasts by more than a factor of 4.

Bob

 

[Bumpkin]

Useful info there Bob

 

[Bobbin-Man]

Thanks for the extra info Bob, very helpful.

I'm getting somewhere with the bits I need although the rubber seal that fits over the TK-2302 SMA socket is proving hard to source, if I can't get one I might need to make one. If I can source the correct cable (I'll try Renair) I plan to use an SMA flexi antenna that can be fitted both to the radio as a handheld, and also relocated to the rear of the bike. The cable would need to be an SMA male to female extension lead with the female end being able to be through-panel mounted at rack (male) end. Only 2 connections in the setup.

I think doing this should give me a good extended range and still be "within" the regulations.

 

[Bumpkin]

Post back here if you manage to source such a cable. I suppose the alternative is to use a regular SMA-M end and find some way of clamping it, or the base of the antenna, in the required position. Panel mount into a suitable bracket would be preferable though.

Sent from my GT-I9505 using Tapatalk

 

[Bobbin-Man]

All my searches have proved futile and sourcing a through-panel SMA male end seems impossible, fairly obvious really because the threads are on the inside! Currently I've ordered a patch cable which is cheap enough if it doesn't work out and I'll probably make a clamping bracket to secure the end to support the antenna.

 

[Bobbin-Man]

Another alternative might be to use an SMA connector I found on ebay which is actually intended to fit the Kenwood radio but could alternatively make a good antenna base. I assume that to be GPI I'd need to insulate this from any mounting bracket.

 

[AberdeenAngus]

Mounted mine on the screen bar. Gives me access to the controls and keeps the antenna vertical.
Unclip it when leaving the bike. Radio and satnav both through Autocom.

 

[Bobbin-Man]

An update ....

Still keen to retain the radio under the seat but with an external antenna, there's enough clobber to detach from the bike when I park up somewhere on a tour without adding a radio to the "must remove in case it gets nicked" list of jobs!

So, the SMA mount arrived .... fairly straightforward to replace the fixed antenna with the new mount, took about an hour

Radio dismantled down to the circuit board, all the PCB retaining screws removed but I left the PCB in situ because I didn't want to disturb the connection to the rotary controls. At this stage the only thing retaining the PCB was the fixed antenna ... I discovered that by applying a gentle lifting force to the board (small screwdriver inserted at the side near the antenna and gently rotated), as the antenna connection was de-soldered the board nicely popped off the antenna tab. It's not possible to de-solder and remove the antenna, but rather the PCB needs to be de-soldered and lifted away from the antenna, approx 5-6mm. Once free the antenna can be removed by pushing in one of the locating tabs in its plastic mount.

With the PCB in the raised position, the new SMA connector can be screwed into place (I tinned the connection before fitting). I then simply reheated the solder joint and the board dropped back over the new connection tab, some more heat and little extra solder should ensure I don't have a dry joint.

I've had no success sourcing a Kenwood dust cover for the SWA connector, there's a supplier in Spain who possibly has some but hasn't responded to my enquires! So, found a suitable panel grommet that's a nice tight fit and cut it in half! It fills the space between the SWA base and the radio case just fine so it should keep dust out satisfactorily.

So far so good. Just waiting for a couple of antennas I've ordered to be able to test the work I've done, and a patch lead to start the mods at the bike end

 

[Bobbin-Man]

Re-assembled ready to go back on the bike ...

 

[Bumpkin]

Neat job

 

[newboy]

can I buy yours off you now you've done it

 

[Bobbin-Man]

You can ..... but you really don't want to know the price

 

[newboy]

lol

doh

 

[Bobbin-Man]

Update ....

I've finally received a couple of antennas ... the stubby is to enable the Kenwood to be used in it's original form as a handheld, the longer one is for permanently fitting to the bike. Both are "UHF 400-470 MHz", the stubby is actually a Kenwood antenna ...

 

[Bobbin-Man]

And .....

Also received an SMA male/female 1m patch lead. Trebor's comments about losses at connections has led me source a cable that gives the minimum connections, although it will result in some difficulty in mounting the antenna without an available through-panel connection at the antenna end ....

 

[Bobbin-Man]

And ...

Routed the cable from the tool tray, under the rear seat section and out via the back of the rear light. I've not decided how to finally mount the antenna yet but the location is fine for use with or without the panniers fitted and temporarily I've held it in place with a couple of cable ties ... it's actually quite secure! Not yet tested and not really sure how far to get the antenna away from the hard bits of the bike when I do fabricate a suitable method to mount it.

Have I sourced the correct bits? Will the antenna location be satisfactory? Anything I've missed?

Stu

 

[Kritou]

It is my experience that RF energy likes to take the easiest path. If your bike frame provides just that the effective radiated signal will suffer. Raising the antenna up a foot or so will possibly give you a significant improvement

You may be able to beg borrow or steal an SWR (standing wave ratio) meter with suitable connections to measure any improvement in transmitted "power" in different positions

If your cable is long enough perhaps a length of hard plastic pipe with a suitable id could be permanently fixed to the frame somewhere at the back and the antenna drawn up through it and taped in place where it emerges?

 

[Bobbin-Man]

Yes I understand, I'll investigate getting it higher ... might need to step it to the side a little to avoid the top box though. I've started low because the "Bikers Oracle" antenna plate was dropping the mounting point down to the bottom edge of the numberplate which seems to have satisfied most people's needs. Thanks

 

[Bumpkin]

I've started low because the "Bikers Oracle" antenna plate was dropping the mounting point down to the bottom edge of the numberplate which seems to have satisfied most people's needs. Thanks

As Kritou says getting the whip out into some clear air can only help the output. Though what you've done so far will be a distinct improvement on having the thing lying down under the seat. I've done away with the BO numberplate bracket and mounted my antenna higher. No real chance for any significant test yet and on this years tour we're going Bluetooth (albeit against my wishes/advice...).

In part this move was down to the BO numberplate bracket putting the antenna directly in line with the exhaust gasses which finally melted the whip in the South of France last year.

 

[Bobbin-Man]

Only catch with the GS is the (Vario) top box is pretty wide and positioning the antenna higher it will need to be a long way out to avoid the side of the case ... example on ADVrider: