I have questions...

Les White

Less is more
2A Bourbon Hound 2024
2A Bourbon Hound OG
Charter Member
Life Member
Multi-Factor Enabled
Joined
Dec 17, 2016
Messages
8,733
Location
DavieCo
Rating - 100%
23   0   0
First. I'm considering an IC706mkIIg to use as a base rig. I understand what an antenna tuner does and it seems like a necessity for such a radio. How do you select an antenna for an all mode radio?

Second. I've put the FT-8900 in the car. There was an existing hole in the center of the trunk that I used to mount a dual band antenna with a NMO mount. The question is when planning to add a second antenna for a second radio, do I need take into consideration any spacing needs? Do they need to be a certain distance apart or the further apart the better? Any concerns about harming one radio while TXing 50w on another with the antennas in such close proximity?

On a side note, I put a Tram 1480 on the house, maybe 40ft total elevation, and with a 5w "bo-bo brand" (baofeng) HT was able to hit a Ashville 2m repeater @ 128 miles. Pretty impressed with that.
 
Last edited:
The tuner is used only on the HF side of the 706. Get an automatic tuner with 706 interface cable. Then you'll use the Tune button on the 706 to start the automatic tune. No tuner is used on the V/UHF side of the 706. I have a IC706MkIIG in my truck and it's great. I had a second 706 on base many years ago. It was a good base, too.

If you'd like to use one antenna on the FT-8900, consider the Comet UHV-6. It is a 6m/2m/70cm/HF antenna that works very well. Install it in your existing mounting hole with the 10M coil (included) and the one antenna will service all 4 bands of your FT-8900. https://www.gigaparts.com/comet-antennas-uhv-6.html?gclid=COjQzayB-dICFU42gQodMq8KUg
 
Hi Brian,
I've got a 706 as well (Mk II, I think). I use it mobile and it works well. It needs an antenna tuner no more or less than any other solid state transmitter....so if you cut some dipoles for the bands you want to operate on , you'll not need one. I have a very heavy duty Heathkit tuner (1KW easy ) in my shack and rarely use it.

Antennas on HF are really not defined by "mode" as much as by band. The antenna (and the rig) won't care what form of RF is coming out of the business end into the antenna , but they ARE defined by the frequency of operation . So , an antenna that's good on 10m CW will be fine on 10M SSB and 10M RTTY, and 10M WISPR, etc... it's only when you deviate widely from the resonant point of an antenna is cut for, that you MIGHT need a tuner. On the higher bands (Say 40-10) you'll likely be fine with a single resonant dipole (element) for each band. On 75-80 and from CW on 160 to the top end, you'll likely need a tuner to handle the frequency excursions. I guarantee you, the station on the other end will never know if you have a 1:1 SWR or a 2:1...

So... for HF, it all depends . Resonant antennas do away with the need to worry about effective RF grounding, additional knobs to turn, etc. They also cost little more than the cost of the wire to make them.

Keep asking questions and keep it simple!

That's my 0.02. The fun part of ham radio is there's a lot of ways to skin the cat.

Welcome!
John
 
One comment on the tuner power rating versus mode. Be sure you read the specs on the tuner because some that are rated for X watts mean that is for a mode like SSB which doesn't output full power continuously like some of the digital modes do.

I bought the LDG AT-100ProII and this is what it says:
A: No. The power ratings are for PEP SSB or CW. For 100% duty cycle modes (digital, RTTY, AM) the power limit is about one-third of the power specified. If you wanted to run 100 watts digital, the AT-200ProII would be the better choice.

Note, though, from what I've come to understand a lot of these digital modes work better on lower power levels, so this isn't necessarily a big issue.
 
I think it is important to consider that an antenna impedance matching unit (tuner) is more than just an impedance matching device. Tuners generally cost a fraction of the radio. In addition to providing impedance matching, a tuner is also a protective device should unknown antenna system changes occur over time or suddenly. A tuner between the radio and antenna system can act as a guardian that may be sacrificed during antenna or coax adversity. Tuners are cheap, radios generally not.

I read his question to be how to choose and connect a tuner for the all-band IC-706 radio. BTW, I use a LDG-7000 tuner on my 706 in the truck.
 
One comment on the tuner power rating versus mode. Be sure you read the specs on the tuner because some that are rated for X watts mean that is for a mode like SSB which doesn't output full power continuously like some of the digital modes do.

I bought the LDG AT-100ProII and this is what it says:

Note, though, from what I've come to understand a lot of these digital modes work better on lower power levels, so this isn't necessarily a big issue.

You bring up a good point . The lower-end tuners are limited because of the duty cycle of the mode . I suspect the less than awesome rotary switches or relays involved can't handle 100% duty cycle modes like some of the digital modes and rtty.
 
Last edited:
Thanks for all the input. It's helped but has raised even more questions.

When using an all mode radio as a base, how do you select an antenna? Or is it best to select antennaS on a switch? Maybe a vertical for 6m-70cm, and a dipole for 80m-10m?

I've got a cheap Tram 1480 on the house now which really improved range. For HF I'm considering a vertically hung end fed dipole in one of my huge pines, paired with a MFJ993.....but I've got time, still need to take the general exam.
 
There are two antenna connections on the 706. One is HF+6M and the other is 2m+70cm. You only need an antenna switch if you are using more than one antenna for each of these connections.
 
Thanks for all the input. It's helped but has raised even more questions.

When using an all mode radio as a base, how do you select an antenna? Or is it best to select antennaS on a switch? Maybe a vertical for 6m-70cm, and a dipole for 80m-10m?

I've got a cheap Tram 1480 on the house now which really improved range. For HF I'm considering a vertically hung end fed dipole in one of my huge pines, paired with a MFJ993.....
That will certainly work....and likely well. ...and you can't beat the installation cost.

Give that vertical dipole a try and see how it goes. You want to make sure that the inner side of the coax goes to the higher part of the wire naturally . Get that on the air and let us know how it works . You can worry about things like antenna switches later. In the meanwhile get on the air and have fun


:)

John
 
Back
Top Bottom