Відео

In vintage vacuum tube amplifiers, the secondary connections of the output transformer were often color-coded, and while there could be variations depending on the manufacturer, a common standard was: Black: Common (ground) Yellow: 4 ohms Green: 8 ohms Brown: 16 ohmss You could verify this by making some low voltage ratio measurements between these connections and the primary. Be sure to use a low voltage signal generator so as to not develop any high voltages across the high impedance primary (the wires that go to the vacuum tube plates and B+) remembering that voltage ratios are the square root of the impedance ratios. Hope this helps. There are other ways if this doesn't make sense or help.

hi my out put transformer is a hammond threre is little plate with a number 1664 thanks i will try @@ElPasoTubeAmps

Hi Ben, The one I have that I like is TrueRTA. Here is the link. trueaudio.com/rta_down.htm I think it is worth the price for the license beyond the free version because it prints beautiful images with your name exactly as you put it in when you install it. Another one is SpectraPlus but it is very expensive. Here is a video where I use it and show the very nice printouts. ua-cam.com/video/eU62EfGWNHg/v-deo.html There is another one called ARTA as seen in this link below but they just went out of business as of March 2024. ua-cam.com/video/BBQyoHsmwL8/v-deo.html Hope I got these right... Thank you so much for your kind words. It makes all this effort worthwhile. The 8903A and Pete's software was a challenge.... but it still works. I had a leak in my shop a few years back and it leaked water on one of my PCs and I lost one of my most important PCs but fortunately was able to move the hard drive into another PC. Now I get constant - this is not authorized software - or something like that - from Microsoft but it does work. I just keep that PC off the Internet. I still have my 3580A also as it is such an icon of a SA. As you know, it is brutally slow on low frequency signals. As I searched for FFT software, it seems like much of it is going away. What is our world coming to? 🙂 In another 20 years, it seems there won't be many of us that like to do this stuff, still around. Lastly, I forgot to mention about the first software I listed - you need and external USB sound device but I am sure I show it in some of my video. Again, thanks for contacting me. I don't do many videos anymore. Time is sneaking up on me and it is hard to get the energy to do them. Best wishes to you, always. David Beard

@@ElPasoTubeAmps David Thanks for the quick reply. Please don't quit making videos. I've learned so much from your material and many others refer to your work. Blueglow electronics mentioned your HP 3580 and I've had several conversations with other hobbiests who also have pointed to your work.

In my quest for Spectrum analyzers I could use some insight from you. Currently I have an HP 8590a which I received first very cheap and supprisingly it work great. Then I got an HP 8560a (not so cheap) which goes down to 50hz and up to 2.9 ghz. I was thinking that these might cover both some audio work and RF work which I'd like to do soon as I get the courage to start aligning am and fm receivers. But I'm not sure either of these will really work properly. The 8590a only has an RBW of 3k which I learned does not allow me to zoom in enough. The 8560a is a much better spec going down to 50 hz and an RBW of 10 hz but to get the span down to see that resolution it is almost a crawl. Do have the opportunity to return the 8560a for a full refund so I need to make a decision. (the 8560 does not perform as nice as the 8590a, the image is a little choppy and blurred but its good enough for the RF work not sure of the audio work. The HP 8560a came to $470 with shipping. I'm wondering if my money would be better spend on another better solution. I know you have a similar device I can't remember the model but I remember you trying to calibrate it. What do you use your for? Any insight on if I should keep or return this HP8560a 50hz to 2.9 ghz and pursue another solution I'd appreciate it. I might sell the 8590a too but it is so damn nice...

@@bendec2969 I went that path also trying to get an RF SA to work at audio and it is not a good choice. The old style analyzers like the HP 3580A, utilize a technology based on swept-tuned heterodyne receivers rather than the Fast Fourier Transform (FFT) approach used in modern digital spectrum analyzers. I love my HP RF analyzer, works great up into the GHz range, but for audio the PC based FFT analyzers are far better - in my opinion - although the 3580A is an icon of a swept-tuned SA. With that said, I have to thank you for reinitializing my interest in my PC analyzers. After your comments from last night, I got my TrueRTA program going again - had to look back for a few years in my email to find the code to make it work properly and then "reinvent" how to make the USB sound cards work again - I have always disliked PC's but know I need them nowadays. I am planning on making an audio video using a stereo amplifier - a Williamson design - and making measurements with one channel using 6L6 beam power tubes and the other channel using EL34 (pentodes) and try to document the harmonic profile of the so-called, British sound, of the EL34. Supposedly, the EL34 has more pronounced high order harmonics and gives it that bit of a "rougher" sound of the amplifiers like the Marshalls vs the smoother Fender. I figure it is time I give some attention to my audio fans. I will break out my 3580A and hope it still works. Thanks again. Stay safe.

David, I'm glad I got you going again. Looking forward to seeing that. I recently acquired two EICO HF-22 Monoblocks for a song!! But they are in rough shape right now but have everything. The original tubes test marginal but they'll do for now. Currently they use the 6L6 and I was wondering if I could upgrade to EL34 since there is a similar model that uses the EL34. I didn't consider the performance details just the fact that I have EL34's seem more available and I have several since I use them in an old Traynor Bass amp. Get that video out!!! I think I'm going to watch some of your videos on my 75" TV right now!

I never noticed the knobs were different from other MX-113. I just looked both models up on Ebay. I have had it for years and bought it used and it came that way. I also have the MX-112 and see they originally had the same style knobs. Oh well... I might mention that I had a very intermittent issue with this MX-113 where the FM audio would randomly go in and out and it turned out to be a dirty MUTING control on the top of the unit. Apparently, a dirty wiper on the pot. I mention this as it was so random and intermittent it took me quite a while to find the issue. Thanks for your comments.

I think I would put a lot of insulation between my headphones and my ears if something with 5000 volts was driving my headphones. 🙂 Thanks for your reply...

@@ElPasoTubeAmps YOLO

I understand what you say. I have a Williamson amplifier that I put 7591 in and now they are $52 each - just too much - I will probably change them out (have to make some socket wiring changes) to 5881 that I have lots of. Of all the solid state amplifiers I have, I like the McIntosh 2100 the best. 105W per channel and for some reason like it better than the huge 2205 at 210W per channel. I doubt I will get rid of any of my tube amps but tubes, along with everything else, and taxes, is just going thru the room.

Totally agree - the comment at the top, transcribed from the Mullard document agrees with us also. Thanks for your comments and confirmation.

You have a good point. I like to spice up the equipment some time. I joke that most of my equipment looks like surplus equipment from a cold war underground bunker with the grey chassis. When I get really fancy, I paint my chassis blue like the headphone amplifier I built for my grandson. 🙂 I do like symmetry try to dress the under-chassis wires along the sides of the chassis rather than direct - although sometimes short, direct connections can be the best. I do hope to build some more audio amplifiers soon. Thanks for your comments.

One thing I would like to say about this amplifier is, in the ARRL schematic, they directly wire all the screens together. I found that separating the screen connections from one another is a much better way to go. Everything works better when each screen has a little wiggle-room. I don't see it in this video but I believe I added 470 ohm 5W resistors in each screen lead right at the socket. It did wonders for stabilizing it and improving the output.

My most serious interest does always come down to amateur radio and RF but my YT channel was initially intended to be primarily for audio equipment so I thought it would be more appropriate to have a name not specifically for ham radio.

This amplifier does have screen taps and are used. It evolved into a much more powerful 6550/KT88 amplifier. Not sure but I think I made a video of that version using the 5U4 rectifier and then a solid state rectifier. A good bit more power with the higher voltage from the SS rectifiers. Being very conservative with vacuum tube rectifiers, a 5U4 is really only good for an amplifier of about 30 watts output. I do still have this amplifier.

This was my first modulator to modulate a pair of push-pull 812A tubes in a 1947 James Millen amplifier. It was too small and I ended up with, and still use in my AM transmitter, a modulator using Eimac 4-125A and a BC-610 modulation transformer. This one does a great job of modulating the Millen amplifier. I mostly keep it at 7293 KHz so maybe we will meet on the air some time for a QSO.

🙂 Absolutely... that solder resin keeps the mustache under control and comb the cats with it too ... 🙂

@ElPasoTubeAmps Well played, my friend. Make it a great day . Til next time. 73. DESPERADO 56 north of Tampa FL. When conditions are right.

I use an external USB sound card like, in this case the Behringer or maybe a Focusrite or whatever you might have that the ARTA software can connect to thru the USB port. I am confident it can find any USB unit. If the external sound unit has mic input you can use that for high gain, if you need it, or use the line level mode for higher voltage levels from the device you are measuring plus some attenuation network, etc. to get the input signal to a level the sound unit can handle.

@@ElPasoTubeAmps ok, can i use such thing for measure the gain of smps ? I develop resonant converter whixh need to explore the mag gain

@@endremurti Sure, if you can measure the input accurately and then the same for the output or you can do 10*log of the power ratios with a volt meter. I am not sure the dynamic range of this FFT device is adequate to measure input accurately but I may be wrong. You will just have to try. I can give you an example. Suppose your driving voltage is 1.5 volts across an input load of 500K (you convert this to input power and get 4.5 microwatts) and your power output is 50 watts, the gain would be 10*log (50/4.5E-6) = 70.46 dB. Hope this helps.

Tom, per all the specs on Hg rectifiers, only a choke input filter is recommended but I have used these rectifiers with capacitor input filters and in voltage doubler circuits which by design has capacitors at the output to the rectifier - running them at 4KV output - and never had any issue. I would keep the size of the input capacitors relative small, as you mention, at 40 uF or below. You are right, these Hg rectifiers are tough. I like to call them the solid-state rectifiers of 1930... voltage drop is constant at about 15 volts regardless of the load. As for the 3B22, it is a full-wave rectifier so you need only one. Thank you for your kind comments. I learn something from you all every time I post a video and have met many very nice people over the years on UA-cam. Stay safe...

@@ElPasoTubeAmps Thanks again for such a thorough response. Regarding the xenon gas 3B22 would you say it also could tolerate a 40uf first capacitor in the power supply? Since it only is rated for 725V PIV have you run it past that? I suppose a 1N4007 in series with it would help.

I was inspired by this video to run a test. I ran two tests, one with dual 649/5834 mercury vapor rectifier tubes and then dual 3B22 xenon rectifier tubes in a full wave CT arrangement on a Hammond 278cx power transformer. I coupled them to both a 2000 ohm load and then a 1000 ohm load, representing approx 250ma and 500 ma loads as might be expected in higher power amplifiers. The filter network I used was a 100uf capacitor, then a .5mh choke then a 120uf capacitor. I certainly exceeded the piv rating as I had over 1000V piv. Neither the relatively large first cap nor the piv spec busting did I notice any problems. They even withstood switching (after warmup) into completely discharged caps without arcing. They also, as you show in your video, have much less voltage drop than vacuum rectifiers. The 3B22 xenon tubes had less voltage drop than the mercury tubes. I intend to use these tubes in my next tube amp.

@@tomlang6480 I have experienced similar performance. The PIV rating is very conservative and so is the current rating. I used 866A rectifiers in a voltage doubler circuit raising 1800 VAC from a 700 mA transformer to 4KV for an 833A RF amplifier and never had an issue. The ratings of Hg rectifiers are always into a choke input filter and the voltage doubler by design is capacitor input to the filter. I turn the HV on during transmission of off during receive so there are many cycles of on/off and I never had an issue with the Hg rectifiers charging a 40 uF capacitor at the input of the Pi filter network. I don't have as much experience with the 3B22 but I figure it is just as tough. Thanks for your information and comments. Stay safe. Here is a link for vintage components you might like. n4trb.com/AmateurRadio/RCA_Ham_Tips/rca_ham_tips.htm

@@ElPasoTubeAmps No kidding about staying safe! I notice after all these years (decades) I automatically put my left hand in my pocket around this stuff.

Thank you for your comments. Been a while since I have used this device but still have it in good condition. I don't know if I mentioned it in the video, the cables from the amplifier socket to the test jig may introduce instabilities in some amplifiers if the amplifier is swept with a sine wave. I bought ferrite cores to put around the grid an plate wires but never got around to it. Also some small bypass capacitors in the 100 pF range might help quell any parasitic events but for static measurements it is really handy for matching tubes. Stay safe...

I think you need another base and switch assembly that you can take parts off of to save your heirloom microphone. They are not too expensive on Ebay. I have one similar that was bought for me in 1963 when I got my general class license - 61 years old - and is special to me. I keep them going and have acquired several heads to experiment with different mic elements. I have also found that the inexpensive condenser mics sold on Ebay and Amazon have a QC problem. Some work much better than others so a simple method of evaluating them would be good. I just ordered some more... 🙂 and will work on a method to sort the good ones from the weak ones and plan on making a video. Thanks for your comments. I hope you can save your 70 yo microphone for another 100 years. 73 WA4QGA

Thank you. You are very kind. Here are a couple of additional videos when I got more serious about it. Yes, the antennas are very directional and need a good size tripod to mount them on. ua-cam.com/video/KLhxggZbsVc/v-deo.html ua-cam.com/video/SDLm1N10fTI/v-deo.html