Palstar AT1KM 1:4 ruthroff balun - a wrong choice?

 I own a discontinued Palstar AT1KM. I consider Palstar as one of the best antennatuner builders. The tuners are expensive but quality is very good. It works fine, actually I never had troubles with it and tuning is very easy. However, in the past even antennatuner builders had it wrong. 

A while ago a began to read about baluns and what they do. I read several tests with baluns at the output of a unbalanced tuner since I was unshure if I should use a 1:4 or a 1:1 balun behind my CG3000 autotuner to feed my vertical. I did some experiments myself and continued to read all about it. Now finally I read a article in a Dutch amateurradio magazine called Razzies about baluns that was a real eye opener. It contained a test with a voltage, current and no balun with both coax and open line. The winner was clearly the current balun in all cases. 

Now, I was thinking....

On the back of a Palstar tuner the balun instructions

Inside the AT1KM is a 1:4 ruthroff voltage balun for balanced output, I guess it was kind of a standard about 10-15 years ago. My MFJ948 also had a 1:4 voltage balun inside. But with the knowledge of today it seems it is not the right choice to make. I was curious if Palstar is still using a ruthroff balun inside their tuner. If I look at the AT-500 the specs tell me they are using a 1:4 current balun, though if I look on the photo it looks like the ruthroff balun in my AT1KM. Two other tuners they make don't have baluns inside anymore. Baluns are now available in a non conductive housing which should be connected with the shortest possible coax to the tuner. the reason: baluns mounted against a metal chassis are subjected to mutual capacitance, which may also disturb the balance.  It is simply better to mount them externally in a plastic box (Owen Duffy, VK1OD). The Palstar engineers listened well...

Actually the same Owen Duffy came to a conclusion: "A unbalanced T match followed by a 1:1 Guanella (current) balun in an external non conductive enclosure and having high choking impedance, very short coax connection to the ATU, and high voltage withstand is capable of excellent performance in a ‘balanced ATU’ role for general purpose HF application."

...Exceptions are the heavier Palstar AT4K and AT5K manual tuners which have a 1:1 balun at the input and mounted inside the tuner housing but not against the housing. At first I though, why not? What difference would it make. This is what W8JI tells about it: "Any article that claims placing a current balun at an unbalanced tuner input helps balance, or generally helps the balun work better, unfortunately is mistaken. Moving the current or choke balun to the input of an unbalanced network makes balance much worse on higher bands, and does not help lower bands".

It is unclear to me why Palstar engineers did choose such a configuration with high power manual tuners anyway? The risk of destroying a 1:1 balun with high power is very high anyway.

So, how to make your T-match tuner work better? Is it that simple? Yes it is....don't replace those 1:4 ruthroff baluns in your old tuner. Let them be. Just make the best current balun you can, place them in a plastic box and connect them with a short as possible coax to your tuner to feed a open line to your antenna. Does it really help? Well, it depends how you antenna is configured I guess. But if you want to feed a open line to you antenna it is just as easy as connecting a good quality 1:1 current balun between the tuner and the open line. You don't have to buy a expensive balanced tuner or a tuner that has a balun inside.

Will we have different thoughts about this subject in the future? 20 years ago it was common to place a 1:4 balun inside the housing of a antenna tuner, most of us didn't have the equipment to verify if this was working right. With the decreasing prices of specialized measuring equipment confirming that your gear is working well is in everyones reach.