antenna hookup for spitfire AM transmitter

I'm not familiar with the Spitfire setup but if like some others it will have a built in antenna tuner which is adjusted by the DIP switches you referred too.

If that's the case putting the antenna whip at the end of a piece of coax will probably not work very well.  The tuner will be designed to match the 3 meter whip which is not a 50 or 75 ohm load.  Putting the 50 or 75 ohm cable between the tuner and the antenna whip would present a big mismatch.

I'm sure someone more familiar with the Spitfire will chime in...

Yes I second what mram said......it wouldn't work. the internal antenna tuner was designed to tune a 3 meter length of wire attached to the antenna jack. Same would go for other AM transmitters also. The Talking House seems to be the one that was designed for this type of install and on that there's a switch setting for indoor or outdoor with coax.

Mark

Some will put the transmitter in a weather proof box and mount it with its 3 meter antenna outside, running cable for power and audio back to the studio.

Talking House/I AM Radio has discontinued their ATU remote antenna, instead putting the transmitter in a weather proof box with whip antenna mounted to the box. This is their new idea for an extended range application.

One can "experiment" with an antenna tuning unit designed for amateur radio that is capable of operation in the 160 meter band. There are a few things to consider though. 1, the coax used with the Talking House is 75 ohms so there will be an inherent mis-match with the tuner as it is designed to see 50 ohm coaxial cable. 2, you will still need an effective ground. And 3, because your tuner was not certified as part of the final stage of the Talking House, you are not street legal.

Pictured in the example image below is the i.AM. Radio system in a box with the 102" whip mounted to the top of the box. I have seen this configuration in person and what I saw was a wire running from the inside antenna screw to the mounting bracket that is screwed into the outdoor case.  The owner imformed me it comes this way from Radio Systems and could not advise me as to whether or not there is another configuration or not, however the 75 ohm F connector is still included on the transmitters cabinet.

The i.AM. Radio transmitter (same as the Talking House) uses the internal tuner to tune up to the 102" whip. Also as some of our regulars will recall, my talking house is housed in a bucket with a conduit pipe attached to the side of the bucket, a short wire from the transmitter to the conduit completes the circuit and yes, the tuner tunes up nicely to the conduit. The conduit was cut to the same length as the factory wire that comes with the Talking House / i.AM. Radio transmitters.

The transmitter configuration I mentioned in the beginning of this post is for a tourist attraction in Kentucky and the unit comes with Cat 5 Cable that is pre-made with connectors on one end for audio and power for the transmitter, while the other end has a box for indoor use that supplies power and audio down the line to the transmitter. 

Announcements are updated using Ftp from a remote site, the files are all named in a manner that allows their staff to update audio files by mearly recording different announcements but using the same file names. Bobs-Message.mp3 would be recorded each time with the same file name but the old message is overwritten using FTP.

Kind of cool.

Barry of BBR 1620 AM

Hi Guys,

I too have a Spitfire and have a question with regards the antenna. This question may sound silly, so please bear with me. Here is the situation.

I have recently moved house and want to set the system up. As you know, the tx comes with a 3 mtr (9 foot) antenna wire. What is the best way to secure this wire to the ceiling (located in spare bedroom/study room). The instructions say keep the antenna wire away from metal objects, so I haven't used a staple/nail/screw hook/ screw eye loop etc to secure the end of the antenna to the celing. I have used sticky tape or Blue Tack instead. Thing is, the antenna keeps coming loose and fails to the floor.

May I use a staple/nail/screw hook/ screw eye loop etc to secure the antenna wire to the ceiling? How do you secure your antenna wire for your tx? (I suppose the same question can be asked in relation to the TH transmitters too)

Thank you

Pat

I have used a glue-stick to hold an antenna wire to the wall from baseboard to cieling and it worked fine.

If you're putting the antenna away from the wall I wouldn't hesitate to use a screw eye-loop. Such a tiny bit of metal won't harm the performance.

"Keep away from metal" is talking about pipes, AC wiring, conduit, large metal objects.

Thanks Carl.

Your answer has brought up another question.

Should the 9 foot supplied antenna wire hang freely from the ceiling or can it be tacked, in some way, to a wall? (You've done this haven't you, tacking it to skirting board and celing? - I'd much prefer your method) Does that solution have any negative impact on this resonance?

Thanks

Pat

You can figure out walls and parts of walls that have electric wiring and metal pipes, and keep your antenna away from those areas.

I chose a wall-space in-between two windows and there are no metalic objects inside that part of the wall.

I drew (very lightly) a straight line from the floor up to the ceiling and rolled a glue-stick aplicator up the whole length, then gently tapped the light-weight white wire up the wall to the top. The gllue held the wire in place all by itself.

The transmitter tuned to resonance in this setup.

There aren't too many places in a room where a verticle AM antenna can be placed without blocking human traffic.

There aren't too many places in a room where a verticle AM antenna can be placed without blocking human traffic.

You are so right there Carl. I used to have the transmitter in the attic, with the top tip of the antenna wedged between two roof joists, leaving it to hang freely...but that was in the previous house. This new house just has a crawl space, so I have to figure out the best work around in the study/spare bedroom.

This new house does however have a 70 foot rear garden, with an outhouse wired with electricity and CAT6 cable, and lots of tall trees. Placing the tx out there and stringing some wire from tree to tree is the long term goal. No doubt I'll be calling back here for some advise on that. 🙂

Thank you for your help Carl.

Pat.