572b tubes problems We found that early Cetron tubes through the early 1980's were very good tubes with high reliability. I would like to change to the 572b tubes but finding a good tube at a fair price seems to be difficult. Installed a brand new set of tubes I bought from RF parts and amp blows fuse. I have only used it for 2 months, and KAARAAACKKK!!!! ,. Examples are the KW1000 and Yaesu FL2100. This time long before the ARRL international test. 1800 volts is probably the minimum you would want to run them at, they run better at around 2500. The Chinese 572B long term life is unknown with mixed reports. The DC blocking capacitor has been replaced as well, the old one blew up. The few tubes that seem to recover from prolonged filament operation quickly revert back to original behavior after being cold for a few hours. Problem is, supplies of vintage tubes are drying up and finding quality new tubes has been a challenge. As far as I am concerned the 572b tube isn't really a good tube for RF with the length of leads inside tube to begin with. Reviews For: Taylor 572B triode transmitting tube Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. Reviews For: Ameritron AL-572 (all models) Category: Amplifiers: RF Power - HF & HF+6M A good 572B should take about 10,000 volts from anode, and show no signs of color streaming or arcing inside the tube. They work great! The table below shows tesults with the new tubes installed. That reduction in temperature screws up the chemistry critical to obtaining full Jul 30, 2012 · hi i have been using some 572b from china seems a bit hit and miss 2 tubes seem ok 1 tube have some internal arcing i burnt them in for 9 hours then very slowly drove them to make sure they would be ok "you can buy those tubes of the company in china driectly if you need such things [ solicitation to buy edited out by the moderator ] cheers Jan 16, 2020 · Not scientific, but good 572B tubes have crystal clear glass and high use 572B have a slight darkening on the glass. Reviews For: 572B Tubes- China Manu. The next attachment is a picture of my temporary test set up and a picture of some 572B's after a test. It seems as though this tube has a severe defect. After burn in 160 meters key down 1000w 45 watt input 80 meters key down 1000w 45 watt input 40 meters key down 1000w 45 Home Messages Hashtags ctrl + shift + ? for shortcuts About · Features · Pricing Updates · Terms · Help © 2025 Groups. Worse case RF cathode voltage for 811 and 572 tubes is around 100 volts. Reduced filament voltage equals reduced cathode temperature when the outlet voltage falls under load. Reviews For: Ameritron AL-572 (all models) Category: Amplifiers: RF Power - HF & HF+6M Apr 3, 2005 · With the AL-572, are you implying that the four 572b tubes would not last very long on am or would they last several years and then need replaced? Also, not sure if that KLV-200 would take my radios 35 watt swing? DXE-572B DX Engineering 572B Power Tubes are available for all-purpose Amateur Radio service. Apr 5, 2005 · The 572b tubes are a very durable transmitting tube. N7XCZ Rating: 2022-04-22 no problems so far Time Owned: 0 to 3 months. Free Shipping - DX Engineering 572B Power Tubes with qualifying orders of $99. RF Parts now has some Svetlana 572B tubes at a very expensive price. We were once again in this situation, so the tubes were replaced. A few comments about the Cetron 572B and another type of filament failure. PS Vane 572b tubes, shipping arrived early so a plus also they seem to be working very good I had Shuguangs before these they did not last over two years. For a period of time, most 811 and 572B tubes were defective from the factory or short lived. Oct 29, 2022 · I recently purchased a Heathkit SB-200. Now, DX Engineering is a source for the popular 572B model power tube, which means operators can finally repair or upgrade their 572B linear amplifiers and put them back into service. The 572B is a direct replacement for the 811A, but has a Graphite Anode for increased performance and reliability. On 14 Jul 2021 at 16:59, Mike Melnik wrote: I have had bad luck with all Svetlana tubes, the last 2 I bought, (EL34´S) new used in a EICO 730 Plate Modulator, I could hardly get any Idle current. Jul 18, 2025 · Ameritron Al572 Repair, Modification's, Vernier Fix, Penta Lab 572b Tubes Amp Repair Guy 4. Reviews For: CHINESE 572B TUBES Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. you have to be very mean to them to make them go south. The Penta Laboratories 572B is a power triode designed for use as a RF Oscillator, Amateur Radio RF Power Amplifiers and Audio Frequency Modulator. The Svetlana 572B also features a low loss ceramic base and a bonded- ceramic plate cap thermal insulator for high power RF transmitting tube capability. eHam. This works quite well and can be used on different tube types once you know what a good tube produces so you can compare results. This eliminates hundreds of watts wasted as heat to give you cooler operations and longer component life. Making use of expensive 572B tubes from China and left over 572B Svetlana stocks are reliable with the 811A amplifier applied high voltage. Tube Replacement 2 June 2023 As discussed above, a clue that tubes are going flat is when maximum output power is achieved with minimum loading. The valve is a hi μ power triode, used in many RF linear amplifiers. These 572Bs are a modern version of the venerable vacuum tube that has been around for a long, long time. Manager Reviews Home Reviews For: Cetron 572B Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. I just recently purchased a new Svetlana 572B tube for my Heathkit SB-200 amplifier. This parrt of the Yaesu FL-2100 repair covers some unexpected bang and the fix for it. Aug 31, 2004 · The 572B is a much higher power triode than the 811A. Radio tubes are valves. net is a Web site dedicated to ham radio (amateur radio). The tube has developed an intermittant short from the grid to filament . A good design would NEVER do something like this. May 23, 2022 · The lower tube closest to fan and variable capacitor, is always difficult to install, so, I have always used a dremel tool and cut a small amount of aluminum chassis out, then sanded down the brass pin sticking out of either the 811A or 572B base, then a tube change can be accomplished, well, at least by me. Typical operating conditions in amateur service are a Va of 2,400 V and an output power from a pair of 400 W. Vacuum Tubes, arcing, vacuum tube failures, advantages and disadvantages of each type of power-grid vacuum tube, vacuum tube grid failures, vacuum tube anode failures, maximizing vacuum tube life, and quite a bit about how power grid vacuum tubes actually function 572B arcing and failures Manager Reviews Home Reviews For: DX Engineering 572B Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. The 572B is a replacement valve for the 811 transmitting tube. I was told that there was a device that would shut it Hello all. Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. Four PSVANE 572B tubes were ordered from Ali Express. Jan 1, 2021 · Collins 30L1 tuningAMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. The tubes have been replaced with new. Come to find out there is a crack in glass next to anode on one and the other tube has a jingle. Reviews For: Ameritron AL-572 (all models) Category: Amplifiers: RF Power - HF & HF+6M Apr 6, 2005 · With adequate filament voltage on that tube, a 572B should last more or less forever in that box. They are more like audio tubes in design. Aug 30, 2017 · I have a FL-2100B amp paired up with a Yaesu Ft101EE and it works well even with the original Cetron 572b tubes. People blame this on higher tube mu or transconductance, but the problem really centers around cutoff bias characteristics. The seller assured me that 572B tubes were new (Cetron) and that he got from 400w to 600w out with 100w drive. io HeathKit-HFAmps Topics Date Date 1 - 2 of 2 eHam. Over a 150 watt DK into it. Click this 572B link and go to stability. Manager Reviews Home Reviews For: Svetlana 572B Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. Jun 7, 2021 · Hello all, I have Ameritron AL-811h amplifier (Quad tube) that I picked up. I think there was something wrong with the wire or assembly, as we were seeing in excess of 10% filament breakage before installation in equipment, and another 5% premature failure within about Jul 19, 2024 · I know I should have never mentioned the amplifier, I realize they are plagued with problems, and looking back I want to know more about 572b tubes parameters. to do this key the amplifier with no carrier or RF input. Sometime after Richardson bought Cetron, we experienced great filament failure with new production. I think there was something wrong with the wire or assembly, as we were seeing in excess of 10% filament breakage Apr 3, 2005 · Running the amplifier from 120 Volts will weaken the Cetron tubes. Does the same thing to the newer ones. This is a serious situation for the thousands of owners of amateur radio amplifiers incorporating these tubes already in service. Also the new Golden Dragon 572B tubes arrived, so we give them a thorough test with some rather mixed results Reviews For: Ameritron AL-572 (all models) Category: Amplifiers: RF Power - HF & HF+6M Apr 8, 2005 · I just received a 2 tube 572B amp. Large inventory of hard-to-find products for the repair and manufacture of Amateur, Commercial & Broadcast radio equipment. Tube 572B or Röhre 572B ID6385, Transmitting Triode, air cooled, and shown. These devices are we believe still available from Svetlana. I am using them in an Ameritron Al-572 on 120V. . Oct 24, 2016 · Heath used American made tubes but today in 2013 the 572B is only being manufactured in China and the quality of the tubes is considered to be not as good as those originally sold with this amplifier (see my note on this below) but if you get a good pair you should still be able to achieve a solid 600-700 watts of output. If you're running it on 120 Volts, and the outlet circuit isn't stout enough, you'll see the color of the filaments inside, dim noticeably with full drive. We can reasonably assume 572B tubes, since they use the same grid assembly and filament, also have this tube manufacturing consistency problem. Instead of a 5 second tune up time and 600-watt PEP output limit, the 572B can stand much longer tune up time and higher output as well, Collins rated the 30L-1 at 1KW input that at 60% efficiency is 600 watts out. It does not appear to me to be designed as a AM power house; more of an SSB amp I would say. You should see around 90 milliamps of Feb 20, 2022 · As most of you already know, 572B and 811A tubes are no longer being manufactured. A pi-network transforms phase along with load impedance. It's like running a box meant for the 572B on "low" side all the time. Slight florescence in tube glass in operation is common and not harmful, but any glow in cold tube internals with application of high voltage is not acceptable. According to what I found on the web, there are at least two problems with them: 1) the Svetlana 572Bs have We found that early Cetron tubes through the early 1980's were very good tubes with high reliability. It is better to add something, even if less-than-ideal, to load the RF path at the filament in all 811 amps and 572B amps. Ameritron's exclusive Instantaneous RF Bias completely turns off the 572B amplifier tubes between words and dots and dashes. Most major Ham supply shops seem to It is perfectly acceptable to replace the 811 tubes with three or four 572B tubes in the AL811 or AL811H respectively to increase duty cycle and tube reliability. Check your idling current on the plates. The Svetlana 572B has a superior getter system based on titanium adhered to the external surface of the graphite anode. Seems murphy has struck yet AGAIN. exploded grid resistor city. New Current This is similar to the Svetlana 572B behavior differences known to cause problems in Yaesu amplifiers, where tubes oscillate on standby. The availability of new 572B tubes from modern Chinese suppliers has been dramatically improved by RF PARTS. These tubes will serve as replacements in any 572B amplifier. The tubes installed are 811a which are down on power, well used for many years. Tests here have shown very little difference, if any difference, between running 572B's for several hours before full-voltage operation and the initial voltage breakdown. Oct 30, 2021 · A more powerful tube to use in the Collins 30L-1 are the heavy duty 572B. I won't edit initial post for clarity. All Penta Laboratories tubes are burned in before testing and matching at their Testing Facility in Ventura, California. A good 572B should take about 10,000 volts from anode, and show no signs of color streaming or arcing inside the tube. Jun 30, 2012 · I directly grounded the grid of tube. 83K subscribers Subscribe Feb 27, 2020 · Good 572b tubes (the original ones with the plate cap terminal) are pretty much gone, except for remaining stocks which are getting thin and rising fast in price. It has… It states a known good tube will draw 250 ma as +44 volts is impressed upon it from the variable B+ supply. I, also, have had bad luck with Svetlana tubes. AL-572 Tubes (or other) issue1 - 20 of 24 1 2 Manager Reviews Home Reviews For: Svetlana 572B Category: Electron Tubes eMail Subscription Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted. Even the tube marked at 250 watts is not that good. 2000 volts will likely melt an 811A with the turn of the switch. The FL2100 design uses a capacitor from the OUTPUT of the pi network back to the input of the tubes. Free Shipping - Ameritron 572B Replacement Final Tubes with qualifying orders of $99. From my understanding the guy that had it before drive it hard. I suggest you look at the 845, 211, or even 805 and run it at reduced ratings. RF Parts Company Catalog. In my case, it was with their 572B clones. They have proven themselves in all kinds of amateur, commercial, and military service. Jan 1, 2021 · Login with username, password and session length Home Help Calendar Links Staff List Gallery Login Register The AM Forum > THE AM BULLETIN BOARD > Technical Forum > Topic: RF Parts 572B Pages: [1] 2 Go Down « previous next » Print 572b's are not well-designed tubes for RF systems. Shop Amplifier Replacement Parts at DX Engineering.