FL-2100B Down

L@@king for info for your amplifier

Moderators: KE7GUY, KC9FOZ, EA5/G0KOM, KG6JEV

FL-2100B Down

Postby AD7GR » Wed Oct 17, 2007 10:29 pm

Hello Everyone,

I am a new member in need of help with my new-to-me FL-2100B. The fellow I got it from was the second owner, obtaining it after an estate sale.

I am told that it blows tubes placed in the right hand position (V2?) "after the exciter power is raised". The fellow said that he used it for about a week without problems then blew the first tube. He tried troubleshooting and lost more in the process. He said that he continued using it on the one working stage without problem.

On checking around inside I found that it is very clean, no evidence of excessive heat or arching anywhere. All ceramic caps look very good... I can't find any cracks or discoloring. The diodes check good.

I found that the grid capacitors on both stages had been paralleled with a 22p cap and that the ALC diode, D202, had one leg disconnected from its solder lug. The Safety Lock switch (S7) and associated resistor (R207) are missing.

I reconnected diode D202.

I do have two, apparently functioning, Cetron 572B tubes --one installed-- and the Operators Manual.

Due to the cost of new tubes I hesitate just plugging it in to see how it goes before at least doing a good job on inspection and any needed correction beforehand.

I have searched for a Tech Manual to no avail and hope to find help here.

Thanks and 73,
Ed - AD7GR
Eastern Oregon
AD7GR
 
Posts: 9
Joined: Tue Oct 16, 2007 10:51 pm
Location: Eastern Oregon

Check the parasitic chokes first

Postby W4CLM » Sat Oct 20, 2007 11:16 pm

Hi Ed,
I'm away at sea currently and do not have a schematic in front of me
right off hand. However in my experience you should check your 22 Ohm parisitic chokes first. Make sure they are in tack and in good order. Not cracked or burned. If need be, loosen the resistor from the coil and make sure they are still 22 Ohm @ 2w resistors as per the original designe of the amp. Idle current keyed down should be about 90ma, about 45 ma per tube and no more. You can run those amps succesfully without having ALC connected, so I don't think ALC is your problem. We use to years ago always run without ALC when using those amplifier with the FT-101 series, when the ALC was connected from the FL-2100 to the FT-101E it would often shut the rig down as it was just too much ALC. So we usually just ran the amp with no ALC line attached and never had any problems that way. So I don't suspect your ALC diode as the problem.

It would be nice to have the interlock switch and resistor installed, but it's not absolutely necessary as long as you are dam careful working inside
of the amp.

Also check the 33 ohm 1w resistors to ground as they really act like a small fuse in a grounded grind amp and nothing more.

Not sure if this has been of any help
73 Carol W4CLM
User avatar
W4CLM
Site Admin
 
Posts: 445
Joined: Mon Jan 02, 2006 12:47 am

FL-2100B Down

Postby AD7GR » Sun Oct 21, 2007 1:37 am

Hi Carol,

Being new to this forum I'm not sure I am responding correctly even though I hit the "Reply" button. I hope this works.

Thanks for the response. I disconnected and measured the resistors you mentioned. The "22 ohm" plate parasitic resistors measure 24.3 and 25.1 ohms and the "33" grid resistors measure 34.0 and 36.5 ohms. I noticed that the grid resistor for V2 is silver banded while the others are gold banded. With that in mind, they seem to be on the edge or a bit out of tolerance.

Yesterday I switched it on, on Standby only. Both tubes glow and fans blow. No nasty smells, no smoke. I read .015A and 2.3KV. After 30 minutes with no problems developing I switched it back off.

Not to worry about being careful... in the 70's I worked on TV's and learned to work with chicken sticks and one hand behind my back. I may be a bit over cautious but I have made it to 62 yrs old so far. <g>

Well... On to the next round. I hope my feedback helps.

Thanks,
Ed - AD7GR
AD7GR
 
Posts: 9
Joined: Tue Oct 16, 2007 10:51 pm
Location: Eastern Oregon

FL-2100B Down

Postby AD7GR » Sun Oct 21, 2007 1:31 pm

Carol,

Another thing that I forgot to mention that may help in diagnosing this. When I first switched on the amplifier the amp gage was at zero and then after perhaps 15-30 seconds there was a "snap" sound and the amperage went to .015A. The voltage began at 2.35KV and after the "snap" eased off to 2.5KV.

I can't recall any other anomalies.

Thank you for taking time to help me. I was an electronic tech in the late '60s but have forgotten almost all I knew back then.

73,
Ed
AD7GR
 
Posts: 9
Joined: Tue Oct 16, 2007 10:51 pm
Location: Eastern Oregon

FL-2100B Down

Postby AD7GR » Thu Oct 25, 2007 6:41 pm

I have been mapping out the wiring of my FL-2100B and am finding some discrepancies, especially in the area of the Standby/Operate circuit.

Since I have found typographical errors in the schematic I wonder anyone has a corrected schematic? The schematic I have is the same one that is in my original instruction manual as well as all of the FL-2100B instruction manuals and schematics that I have downloaded and inspected.

If I need to go through this unit and replace parts I need to know the correct parts and their placement. If anyone knows of a howto that gives instruction and graphics on rebuilding and improving this please let me know. I was unable to get help through Yaesu.

Ed - AD7GR
AD7GR
 
Posts: 9
Joined: Tue Oct 16, 2007 10:51 pm
Location: Eastern Oregon


Return to Amplifiers QRO

Who is online

Users browsing this forum: No registered users and 1 guest

cron