So i picked up this amp, i was told it just needed new tubes. So i took outthe old tubes and installed 2 new Taylor 572B's. as soon as i hit the switch, it turned on and i got a high pitched whine sound and it started drawing a lot of current. I turned off immediately. Popped the old dead tubes in and nothing. Not sure if i need to increase bias or increase cutoff. Maybe i have a bad tube. Any suggestions. Wish i had a known set of good tubes laying around.
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Yaesu FL2000B
- Thread starter Crusher
- Start date
Is the relay stuck or dirty?? I have one of those amplifiers and its an oustanding performer and trouble free and has been for years now those meters should level right out when power switch is turned on there seems to be an issue and Im wandering if someone hadnt been in there playing which is why the tubes puked to begin with.
BJ radionut
Supporting Member and 6m addict
FL2100 Yaesu Oscillation
Fox Tango Yaesu Amplifier page
Crusher: Most likely had old style Centron(RCA) or Raytheon 572b's...
The newer Svetlana(now out of production) and the Taylor(China) tubes do require bias changes...
The Fox Tango 2100B info is near the bottom of the page....other link(W8JI) is an alternate method for same resolution
GL
All the Best
BJ
Fox Tango Yaesu Amplifier page
Crusher: Most likely had old style Centron(RCA) or Raytheon 572b's...
The newer Svetlana(now out of production) and the Taylor(China) tubes do require bias changes...
The Fox Tango 2100B info is near the bottom of the page....other link(W8JI) is an alternate method for same resolution
GL
All the Best
BJ
OK, thanks both. Yeah it had Taylor tubes in it. Guy that originally had it was putting 150W into it (Carrier) gotta love CB dummies. Been working on a few projects. Going to install bias and improve cutoff / idle bias. Amp doesn't key either so i have to figure that out as well.
BJ hit the nail on the head.
I bought one of them of off QTH classifieds, advertised as not working.
It was advertised correctly. After doing the bias mods to get more bias voltage in it I decided to go ahead and do the CT mod with a zener and second relay to provide better stability on the Chinese tubes.
worked like a champ and then I traded it off for some heavy iron HV transformers.
The amp is a poor design and becomes real unstable with the Chi-ma-nese glass in it.
I bought one of them of off QTH classifieds, advertised as not working.
It was advertised correctly. After doing the bias mods to get more bias voltage in it I decided to go ahead and do the CT mod with a zener and second relay to provide better stability on the Chinese tubes.
worked like a champ and then I traded it off for some heavy iron HV transformers.
The amp is a poor design and becomes real unstable with the Chi-ma-nese glass in it.
Yup, just gonna do bias thru CT like in links. Going to use a 50K ohm for cut off. Haven't found what vaule for Zener, anyone happen to know starting point?
TOny sorry back to you so late, been busy with school.
the Bias was allready modeed using a voltage doubler. that is just a band aid.
The real way to set it so it will provide cut off bias is through the CT using a zener and a resistor. That way it has definate bias and cutoff.
the CHI CHI tubes are ok, getting better than a few years ago but they seem to have a higher gain that the old Centrons and thus will take off into self oscillation unless more bias is provided than the original design allows.
I agree. I installed a 50 K resistor off CT to ground, amp still conducts. Funny thing is if i play with Load cap some, amp goes into oscillation. Think im going to have to rework the amp totally for bias and parasitic chokes. Not sureif this one has feedthru cap from plate to cathode like newer 2100b. But man is this sucker unstable.
fl2100zres
Afgter installing most if the mods on this page the one I had was stable ten through 80 with good output. Good luck
Afgter installing most if the mods on this page the one I had was stable ten through 80 with good output. Good luck
Now mine and another 2100B were bought several years back from Burghardt Amateur in South Dakota and the amater buddy of mine who purchased them said mine was the better of the 2 he had shipped to him and that mine had all the upgrades already done by Burghardt themselves.
Mine looks brandnew has plactic on the front faceplate yet and still has the original quality control tag hanging off the power cord!!! The inside also looks new no disscoloring rust nothing. Ive had it open twice to blow dust out which I do every so often. I used this amp on 80 - 10 meters without any issues or problems.
This thing looks nice works great and is a true work horse and has never let me down. The Heathkit SB-200 is the exact same amplifier inside the case. Ide like to get either a Heathkit SB-220 or theres a Kenwood TL-922A that also runs a pair of 3-500Z tubes as the SB-220 also runs I wouldnt mind either amplifierso maybe after winter Ill look into one of the 2 amplifiers.
AMP SUPPLY also made a nice amplifier I could have got years ago that was all rebuilt and upgraded but I was nervous about the fella shipping it from Florida because of a misshap or demolition job that U.P.S. did on a Yaesu base rig I had completely redone and a amplifier I had repaired when they were shipped back to me a few years back that was never settled!! so I backed out and now could kick myself in the @$$ everytime I think about it or the guys on 75 meters bring it up a razz me about it. Theres a nice nwer Heathkit model I see every now and then on the net forsale. I believe its a Heathkit 1000 or something of the sort and it looks just like the Amp supply I like. All in all my Yaesu 2100B is stable and never went weird on me so Im happy about that and like I said the friend of mine that purchased this amplifier had told me he didnt have to do anything to this amplifier because it was already upgraded.
Mine looks brandnew has plactic on the front faceplate yet and still has the original quality control tag hanging off the power cord!!! The inside also looks new no disscoloring rust nothing. Ive had it open twice to blow dust out which I do every so often. I used this amp on 80 - 10 meters without any issues or problems.
This thing looks nice works great and is a true work horse and has never let me down. The Heathkit SB-200 is the exact same amplifier inside the case. Ide like to get either a Heathkit SB-220 or theres a Kenwood TL-922A that also runs a pair of 3-500Z tubes as the SB-220 also runs I wouldnt mind either amplifierso maybe after winter Ill look into one of the 2 amplifiers.
AMP SUPPLY also made a nice amplifier I could have got years ago that was all rebuilt and upgraded but I was nervous about the fella shipping it from Florida because of a misshap or demolition job that U.P.S. did on a Yaesu base rig I had completely redone and a amplifier I had repaired when they were shipped back to me a few years back that was never settled!! so I backed out and now could kick myself in the @$$ everytime I think about it or the guys on 75 meters bring it up a razz me about it. Theres a nice nwer Heathkit model I see every now and then on the net forsale. I believe its a Heathkit 1000 or something of the sort and it looks just like the Amp supply I like. All in all my Yaesu 2100B is stable and never went weird on me so Im happy about that and like I said the friend of mine that purchased this amplifier had told me he didnt have to do anything to this amplifier because it was already upgraded.
If your 2100B oscillates, it's usually not a bias issue. Yes, the new tubes have more gain and reducing the bias may make it stop oscillating but the real issue would be the grid bypass caps. I think they use 220 pf caps from grid to ground on these amps. Between heat and age those caps have lost much of their value now. Replace them with dipped silver caps and watch the stability come back on 10 meters.
Thanks, I'll check that out as well. Been working 65-75 hours a week and just aint had time to fiddle with it. Hopefully in a few more weeks will have the time.
Well I made several changes to amp. Ran bias and cutoff thru CT of transformer. Changed parasitic chokes. I directly grounded the grid of tube. 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. Installed a brand new set of tubes I bought from RF parts and amp blows fuse. Come to find out there is a crack in glass next to anode on one and the other tube has a jingle. Looks like I'll be sending these back to RF parts. Good news is when I adjust tune or load cap with old tubes, amp doesn't try to go into oscillation anymore.
Sounds like you are making some progress.
By directly grounding the grids you may have to adjust the tuned input or in severe case change some cap values in it.
How is it doing on 80 meters as far as output with the grids directly grounded?