Flex 6300 ATU and shortwave bands

PB Shell - k7shl

I have a new 6300 with factory installed ATU.  I've notice that the ATU only works for the ham bands and is not active on the shortwave.  Is there any way around that?

Jim Gilliam

Think you need an external antenna tuner that uses continuously variable inductors and capacitors.

Jim, K6QE

k3Tim

Best I can offer is to set one slice to your SWL band and the other to the nearest ham band with it set to XMT active. That will engage the ATU to be tuned approximately to the SWL band. That is what I've been doing it here with good results.

k3Tim

Bob K8RC

An antenna tuner system like this has to transmit in order to be able to tune. Since transmit is inhibited outside a ham band: No Tune.

Jim Gilliam

The Flex is well-suited for using an external tuner for SWL'ing. When the tuner is matching the antenna to the receiver the noise floor will rise. It could be sharp or it could be broad, but when you get the highest noise floor you have a match to the antenna.

Jim, K6QE

Al K0VM

On receive, an antenna tunner will not change the signal to noise ratio unless you have a really punk antenna. The ATU in bypass should give you all of the signal to noise ratio that you will every likely to get.

AL, K0VM

PB Shell - k7shl

Well, if I were to tune in a regular commercial AM station, I  do well at the upper end (which is closer to 160M), but the signals are very weak on the lower end, even for local radio stations and not some DX in another state.   I think Tim's comment bears the best solution short of getting an external antenna tuner. But, thanks.

KF4HR

I got tired of hearing my Flex ATU relays being beat into submission.  Now I keep my Flex ATU in bypass and use a Palstar HF-Auto Tuner.  It has the capability to tune automatically or manually so on the shortwave bands it's just a matter of manually tuning for max noise floor.

Dan -- KC4GO

You might want to look at http://www.mfjenterprises.com/Product.php?productid=MFJ-1045C   about $90.00 
the issue is you have to be sure not to transmit with it in line. On my 6500 it's on the RX-A port and the antenna is well removed from the TX antenna so no problems so far. On you 6300 you will have to use one of the ports that can be transmitted into. 

HCampbell WB4IVF

I believe K0VM is correct.  If you have a halfway decent antenna, even a simple outside long wire, I don’t think an external antenna tuner, preamp, etc. will help much, if any.  Sure the signal level will increase, but so will the noise.  If QRM (such as interfering stations or local noise) is a problem, a directional Rx antenna may help.  I have 2 reversible beverage antennas at right angles which I can switch between.  On 80/160M (and commercial AM BCB), the Rx improvement over my Tx antennas is impressive.  There are many other directional Rx antennas (such as small loops) that require much less real estate than a beverage.  

Dan -- KC4GO

The pre-selector also acts as a band-pass filter which is not included in the 6300 and on the 6500/6700 only for ham bands. 
The band-pass activity can reduce the effect of strong off frequency signals  on your receiver. I find it useful.

PB Shell - k7shl

Well, I have a multiband vertical.  My ATU on my ICOM 7600 would always beef up shortwave and commercial AM with that antenna.  Guess I can set up a long wire on ANT 2 and see how that goes.

HCampbell WB4IVF

Phil, I have the ICOM 7410, which is a fine rig and am keeping it for backup (it has super NR/NB when I need it).  FYI, here are AB4OJ’s comments about the 7410 (which may apply to your 7600?) for out-of-band Rx use in his ICOM 7410 Yahoo group:

“The IC-7410's RF bandpass filters (preselection filters) are contiguous half-octave filters which cover the entire range 1.6 - 60 MHz without gaps. Thus, receiver performance is constant across the entire range. Many "ham bands only" receivers have preselection filters a little wider than each amateur band, so the receiver sensitivity is optimised for the ham bands and falls off "in between".   The IC-7410 is very well suited for SWL service.  One should not forget, though, that an HF receiver does not need (nor can it use) a low noise figure, as the band noise below 30 MHz is usually 10-12 dB above even an average receiver's noise floor. “
http://www.ab4oj.com/icom/nf.html

Al K0VM

The ATU in the 6xxx and many other tend to act a low pass filters ( series L / Shunt C ) and will provide some attenuation on frequecies above their tune frequencies and nearly no attenuation below..

AL, K0VM