[Yaesu] FL-2100B, Help Troubleshoot...

[KBØNLY]

Switch checked and triple checked, the tap for the 10m coil is fine, 
continuity good, no problems there.  I am stumped.

73,

Scott KBØNLY


-----Original Message----- 
From: Martin Sole
Sent: Friday, May 18, 2012 11:47 AM
To: 'KBØNLY' ; 'Yaesu Reflector'
Subject: RE: [Yaesu] FL-2100B, Help Troubleshoot...

I'd still say it's in the output circuit, and the fact that you replaced the 
switch might well be the key. The tank aint resonating since there ain no 
dip! Check the 10m coil tap and measure for continuity when it gets switched 
in. Most likely you are trying to get power out through a tank that's either 
resonant near 15 or else the whole coil is in circuit, not sure how they 
switch that.

Cheers
Martin, HS0ZED



-----Original Message-----
From: yaesu-bounces at mailman.qth.net [mailto:yaesu-bounces at mailman.qth.net] 
On Behalf Of KBØNLY
Sent: 18 May 2012 23:40
To: Yaesu Reflector
Subject: [Yaesu] FL-2100B, Help Troubleshoot...

Hey all!  I got a question here on the Amp I have been working on, I have 
worked on a few of these but this one is acting odd.

Here is the story... The amp had a burned band switch, I helped Multi Tech 
Industries design a new one, it will be on the market soon in case anyone 
needs one, and I got the switch installed.  New tubes.. A couple new 
capacitors, the 1000pf cap on the plate end of the RF Choke was broken by 
the previous owner removing the blown bandswitch.  And one cap on the T/R 
relay, a bypass cap, was broken as well, looks like someone just caught it 
on the bench and cracked it while trying to work on the amp.

Tossed in a new set of tubes, let it warm up a bit, checked the bias, 
adjusted.  Tried 80m, perfecto... 600w output with 50w drive and the tubes 
are looking good, voltages and current looking good, no problems.  Drop to 
40m, same thing 600w and no problems.  Drop to 20m, again no problem and 
600w output.  Drop to 15m, about 400w output and a very hard to find dip on 
the plate, but otherwise the current is where it should be and it looks ok, 
I think on 15m I actually just have a bit of an input SWR problem and the 
coil for that band has been adjusted its not in the stock location so I will 
have to put the analyzer on it and tweak it.

Now comes the problem...  10m is dead.  According to my radio the input SWR 
is below 2:1 as its not backing off, the current on the amp comes up but the 
plate capacitor has no apparent dip, meter never moves, tuning capacitor 
doesn’t seem to make any difference either, there is ZERO output on 10m.  I 
mean dead dead dead.  So the only thing I can think, since the output 
bandswitch is brand new is that I have a problem in the input section of the 
amp.  I checked the input bandswitch for continuity in the 10m position and 
its fine, I inspected it with a flashlight and a small dental mirror, no 
contact problems there.  The coil for 10m looks ok, and the tuning slug 
doesn’t appear to have been moved.

So, could the cap on the 10m input, 1000pf, be bad causing this?  If so why 
wouldn’t my radio be complaining about a high input SWR?  And why would the 
plate current come up when drive is applied but no output?  Very very 
odd....

73,

Scott KBØNLY


______________________________________________________________
Yaesu mailing list
Home: http://mailman.qth.net/mailman/listinfo/yaesu
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Yaesu at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.2176 / Virus Database: 2425/5007 - Release Date: 05/18/12