Replacing 811a With 572b. 1400 V). More about this upgrade on my website:more Subject: R
1400 V). More about this upgrade on my website:more Subject: Re: [Amps] Replacing 811A with 572B > >> The AL-811H runs about 1600-1800 volts HV, not 1400, which is >> why it's not a bad idea to run the 572Bs in that amp. The 572B is taller and wider If the AL-811A plate voltage runs that high it is exceeding the "Maximum Plate Voltage" rating for the 811A tube and is a bad design. The 572's thrive with about 24-2500 volts The internal structure is well supported and is aligned with respect to the base pins to avoid internal shorts in equipment designed for horizontal tube mounting. > I don't think it's a good idea but he insists a lot of A lot of guys replacing 811A's with 572B's have reported slightly worse IMD due to the tubes not being run with optimum plate voltage. The RCA data sheet calls for 1500 V maximum in ICAS Previous by Date: Re: [Amps] Replacing 811A with 572B, k7fm Next by Date: Re: [Amps] Replacing 811A with 572B, Scott Manthe Previous by Thread: Re: [Amps] Replacing 811A with HI I plan to possibly use the 811A in an amplifier. > > > > The 572B is taller Re: [Amps] Replacing 811A with 572B, Bill Fuqua Re: [Amps] Replacing 811A with 572B, jeremy-ca Previous by Date: Re: [Amps] Replacing 811A with 572B, Joe Subich, W4TV Next by Date: Re: [Amps] Replacing 811A with 572B, Joe Subich, W4TV Re: [Amps] Replacing 811A with 572B, Paul M Dunphy Re: [Amps] Replacing 811A with 572B, jeremy-ca Re: [Amps] Replacing 811A If the AL-811A plate voltage runs that high it is exceeding the "Maximum Plate Voltage" rating for the 811A tube and is a bad design. The thin tantalum plates simply collapse. Here I show the repair and modifications of a Ameritron al811 Amplifier New set of penta labs 572b tubes more RF Parts lists the Marshall 811A at $29. > > If the AL-811A This article examines the performance of the Ameritron AL-811H amplifier with the supplied 811A tubes and with 572B tubes, and details a Shop Amplifier Replacement Parts at DX Engineering. This is a serious situation for the thousands of owners of amateur radio 572B is a lot more rugged, and generally is a drop in replacement for 811A. Given these parameters, the answer is yes. An exception to this would be the Svetlana 572B (the real Svetlana, now SED) which is The 572B will not provide any more gain or power output than the 811 unless you modify the power supply for about 40% more voltage (2 KV vs. The RCA data sheet calls for 1500 V maximum in ICAS At 08:37 PM 4/9/2008, Bert Almemo wrote: > Hi guys, > > I have a friend who wants to replace 4x811A with 4x572B in an Ameritron amp. I didn`t find the 811A datasheet but the svetlana is suppose to be a direct remplacement of the original 811A. Upgraded the 811A tubes in my AL-811 Amplifier to 572B tubes. The Svetlana 572B may Here I show the repair and modification of a Ameritron Al-811h 572b TubesEnjoy 572B is a lot more rugged, and generally is a drop in replacement for 811A. I consider the question to be one of replacing Previous by Date: Re: [Amps] Replacing 811A with 572B, jeremy-ca Next by Date: Re: [Amps] Replacing 811A with 572B, Peter Voelpel Previous by Thread: Re: [Amps] Replacing 811A with What kills 811's is exceeding the dissipation during tuning or misstuning. > > Unless the newer tubes are designed for higher plate voltages > the 572B If the AL-811A plate voltage runs that high it is exceeding the "Maximum Plate Voltage" rating for the 811A tube and is a bad design. The RCA data sheet calls for 1500 V maximum in ICAS Previous by Date: Re: [Amps] Replacing 811A with 572B, jeremy-ca Next by Date: Re: [Amps] Replacing 811A with 572B, Peter Voelpel Previous by Thread: Re: [Amps] Replacing 811A with . On the 572B Previous by Date: Re: [Amps] Replacing 811A with 572B, Paul M Dunphy Next by Date: Re: [Amps] Replacing 811A with 572B, jeremy-ca Previous by Thread: Re: [Amps] Replacing 811A The 572B will not provide any more gain or > > power output than the 811 unless you modify the power supply for > > about 40% more voltage (2 KV vs. 45 each and Chinese 572Bs at $39 each, so the price difference at this point is substantial, but not so much so, if you consider the increased life As most of you already know, 572B and 811A tubes are no longer being manufactured. An exception to this would be the Svetlana 572B (the real Svetlana, now SED) which is If you remove the four 811's and replace then with three 572B's, there will be virtually no change in SWR or neutralization. The > The question was whether the 572B was a good replacement in this > particular application.
