วีดีโอ

Guanella absolutely describes a balun that transforms impedance. With two transmission lines on isolated cores, the input and output are isolated for common mode. The output terminals are free to move around to whatever voltage the load dictates for current balance.

@@Jerrythenerdful True, if both windings are on cores. More typically, one winding is on a core and the other is just a delay line. This is commonly done, particularly at higher frequencies, as it separates the balun function from the transformer function. A separate balun can be added, if desired. The balun is then not constrained by the impedance and length limitations of the transformer windings.

​@@JPM1956 Not so in Amateur Radio. Many so called "good name" Balun OEMs (like the one in Texas) and a multitude of sellers on ebay are selling these single-core 4:1 baluns and ripping off the ham radio community! THIS MUST STOP! de DJ0IP

@@JPM1956 A phase compensated transformer with a core only on one winding is not much different than the error Sevick made. Neither one is a balun. But with an independent core or independent common mode chokes, one on every transmission line, a Guanella (current) balun is formed. The high common mode impedance adds isolation between each output port terminal and the input and ground. This lets the balanced side float from the unbalanced side. Actually either side could be balanced or unbalanced when each transmission line is also an independent common mode choke, or it could even be used as an unun or phase inverter. This is the nature of isolating the two sides for common mode. That all goes away if the common mode isolation is killed, which is what Sevick accidentally did. If you go to his book and read the few areas where he discusses balance it becomes clear he did not understand balance, unbalance, and common mode.....nor did he test for it. That is what got us all in trouble.

@@Jerrythenerdful True. My point was that separating the balun from the transformer allows for a more robust balun design. The impedance of common mode currents is generally unknown and can be very high. The design of an effective balun may be difficult or impossible. But back to the beginning... my reason for posting originally was that you seemed to be broadly criticizing the Guanella topology, but the Guanella topology is actually very good for transformers. Anyway, thanks for your video. I think you are doing a good service for the ham community.

Email me at work if I don't show up here. What is wrong with the grid meter?

​@@Jerrythenerdful when trying to tune grid want go up my tech is at a stop

Thank you!

www.ctrengineeringinc.com/tuning-pulser-tuning-pecker-pkr-1/

@ Thank you! This is exactly what I was looking for. Much appreciated 😊

I have not tested that power meter. Sorry

I just listed them at this link: www.ctrengineeringinc.com/tuning-pulser-tuning-pecker-pkr-1/ Be forewarned after the Holidays I am way behind, maybe about a week.

It's too bad they went out of business. They had some good stuff.

@@dheller777 I have the same setup and it works for me. Do you have Tom's tuning on the fly circuit built into your amp?

@bigfranksworld No

@dheller777 you might want to look into it, and some of the other upgrades Tom does

@@bigfranksworld Thank you

Could one use this with an FT 950 and an SB 220? I use a Birdwatt Meter and a LP 100A. Happy New Year, Tom

Thanks Frank. The Daiwa meters I looked at are ok for peaking an amplifier but I would not relay on them for reading the real peak power.

Thanks Dave, right back at you!

The voltage of the diode will not change diode life one bit. The diode is always forward biased into conduction during a fault or surge. The diode forward surge current rating determines the failure point, not the reverse voltage.

Your comment doesn't make sense. The mu makes very little difference in output power in a cathode driven amp. The output and input are out-of-phase and in series in a cathode driven amp. This gives it a high level of negative feedback. Because of that, the major determinant of gain in a cathode driven is the ratio of driving impedance at the cathode and load line at the anode. So much for mu and gain, if that was what you were trying to say. As for power limits, Collins uses much higher anode voltage than 811 tubes should be operated at. Because the voltage is so high the gain is up from normal voltages of 1500 volts. The 811 tubes would make a great deal of power at that voltage, but they are grossly dissipation limited. The anodes are so frail the 811s cannot be used anywhere near full emission without melting the anodes down. The 572s cure that.

@Jerrythenerdful Sorry. Two 572's are not going to produce 1000 watts of RF. If that were true, every Linear manufacturer would have done it. Ameritron had their AL-811 HD with four 572's and stated a maximum output of 1000 watts. No one has a two tube 572 with that much gain, unless you are driving it with over 100 watts in and exceeding plate voltage. IF Collins had higher plate voltage than the 811A's would allow, wouldn't that shorten their life? Yet, many are still in service with near original sets. Try presenting your entire test setup so everyone can see what you are doing. I have seen too many people make claims with black boxes.

@@Ferret488 The gain of a cathode driven amplifier is largely set by the ratio of anode operating loading impedance to the cathode drive impedance. You seem to either not understand that, or be unwilling to accept a common well-known engineering fact. I designed the 811 amplifier series in 1991. The AL811 uses 1500Vdc on the anode. The voltage and power determine the impedance of the loadline, the cathode drive impedance hovers around 220 ohms per tube regardless of high voltage. Thus gain is set by the high voltage and desired power level. This is why we have to re-tune an non-class A RF amplifier at increased drive, the increased power and fixed voltage moves the loadline lower. That also decreases gain. There were no tricks involved. The typical 30L1 I see is about 2000 volts or so operating voltage on a normal 120V or 240V main. That is 25% higher than an AL811 and far higher than the fragile 811 tube should be run. It makes the gain of the 30L1 too high for the anode dissipation in the 811 tubes. But one 572 is almost the dissipation of THREE 811 tubes. The 572 solves the severe anode dissipation problem and gives good safety at the Collins 2kV or so. The filament emission is more than enough in any of those tubes to not saturate. Emission limits are not a factor at these cathode current levels. Instead of wasting time and making up conspiracy theories in your head, run the test yourself and get some data.

Hello Jerry - there is always a keyboard warrior, TH-cam seems to attract them. I carried out the upgrades recommended by you on my AL-811HXCE and fitted 4x572B's, delighted with the results. As a matter of interest which of the 572B valves do you recommend, i.e.' from which manufacturer. 73 & Happy New Year.

​@EI6DPToo bad you didn't listen to what he said before you also made a comment. He specifically said that TWO 572's would output over 1000 watts, not four. It is hilarious that the person credited with helping to design the AL-811 amp is also criticizing the design.