There are some good ideas in this thread.  I'm going to have to try the Rescue Tape or Stretch and Seal.  Coax Seal turns into a nasty goo in the hot desert summers so and gets really hard to apply when the temperature gets above 100 degrees.

If you're careful, lacquer thinner works but it's very messy.  MEK also works, but it's really a bit too nasty for this purpose.  Scrape as much of the coax seal off as you can and then use a rag soaked in the solvent to remove the rest.  You might want to test a piece of scrap coax with the solvent to ensure that it doesn't mess up the insulation.  Please follow the safety guidelines on the solvent containers.

As a last resort, just cut the end off and remake the connector.  It's sometimes easier.

To prevent the problem in the future, try wrapping one or two layers of regular electrical tape around the coax and fitting before you apply the coax-seal.  Then just overlap the coax-seal about 1/4" on each end so it actually seals the fitting and coax.  That way you can unwrap or slit the electrical tape to remove the whole mess and just have to clean up the 1/4" bands left on each end of the sealed area.

Bruce,

My schematic shows D7 as part of the HV supply. I don\'t see a diode connecting D2 to ground, but I may be using a different diagram. If it is part of the D2 Zener circuit, then it affects the bias, which explains the problem. Can you forward a link to your schematic so we can make sure we\'re talking about the same thing?

If it was D1 that you cut out, then you\'ve removed the 110v supply. If you\'re comfortable working with high voltages, look at the circuit description and simplified diagram on page 5 of the service manual to see how the amp derives the bias. If not, please have someone else look at the amp as it can and will bite you.  

Since you removed the diode and tried to use the amp, you might want to have someone look over your shoulder while you familiarize yourself with the circuit.  If D1 was involved, it most likely indicates a tube failure, an arc-over, or a short in D2 but there are other possibilities.

I stay up late and have noticed the same thing, so I try to avoid the site between 1 and 3 AM Pacific time.  The site becomes completely unresponsive at times.   Unfortunately, that's kind of my prime surf-the-net time.

Bob

"Hang up 120-feet of coax. Connect the center conductor and shield together and connect it to the output of a wide range tuner. Connect a good radial system to the ground terminal on the tuner."

Wow Bob!  I've never seen that one in the ol' Antenna handbook but is sure does sound easier to make than those pesky tuned wire antennas I've got out back.  Can I accomplish the same thing with ladder line?  (wink wink)

Bob

Also, be aware that any email you send can and will be read by others.

The MC to MHz conversion created a lot of heated discussion at the time.  It was like electron vs. hole current.  Both MHz and "holes" drove me nuts at first.  Now I don't think twice about either.  I suspect that most of today's controversies will go the same way.

Have you verified that the jumpers inside the SignaLink are installed correctly for you cable and radio?   You can take a look at the settings at http://www.tigertronics.com/

I answered this in teh Amplifier forum, but figure I'll move the conversation over here...

I always turn up old equipment using a variac.

In reforming a cap, you are allowing time for the aluminum oxide layer to build back up on the foil. That oxide layer is an integral part of the capacitor and forms between the foil and the electrolyte. If the capacitor isn't used, the oxide layer can degrade. If you apply rated voltage to a cap in that condition, it will almost certainly fail. If the electrolyte has dried out, or if the cap has shorted, nothing you can do will fix it.

If the caps are bad, this process allows a chance to find out about it before you wipe out a bunch of other parts in the power supply and, as you mentioned, it can be such a pain to clean up after a cap failure.  If the caps are good, other than the degraded oxide layer, you give them a chance to reform that layer and they should be OK.

I usually just replace the caps anyway since I'm already poking around in the circuit, but there are a lot of reasons why you might want to keep the originals (authentic look, money, availability, etc.) Reforming is the safest way to go. Just my opinion. Let's see what others have to say about it.

73,
Bob

I always turn up old equipment using a variac.  

In reforming a cap, you are actually allowing time for the aluminum oxide layer to build back up on the foil.  That oxide layer is an integral part of the capacitor and forms between the foil and the electrolyte.  If the capacitor isn't used, the oxide layer can degrade.  If you apply rated voltage to a cap in that condition, it will almost certainly fail.  If the electrolyte has dried out, or if the cap has shorted, nothing you can do will fix it.

If the caps are bad, this process allows a chance to find out about it before you wipe out a bunch of other parts in the power supply and, as you mentioned, it can be such a pain to clean up after a cap failure.

In most cases I just replace the caps anyway since I'm already poking around in the circuit, but there are a lot of reasons why you might want to keep the originals (authentic look, money, availability, etc.)  Reforming is the safest way to go.  Just my opinion.  Let's see what others have to say about it.

73,
Bob

Did you happen to use a 555 timer to generate the waveform?  If so, use your o'scope to verify if the waveform is a sine wave or a square wave.  You may need some output filtering to remove the harmonics if it's a square wave.  If you have a sine wave, you could try coupling the audio from your circuit through a .01uF cap (or whatever you have handy) to the encoder input of the radio as an experiment to determine if you are loading down the circuit.

I haven't worked on one of these, but from a quick look at the schematic it seems like you could inject the tone at the center wiper of VR2 on the FM-IF circuit board.  You might be able to tap in at TP2 on that board.  

The service manual is available at http://mods.dk/manual.php?brand=kenwood

If that doesn't work, or if you find that it interacts with the Tone switch operation, you can try injecting it around VR3 on the Generator board.  Again, I haven't studied the schematic for more than a few minutes, so these are just suggestions to get you started.  Perhaps someone with more experience with this radio will have a better suggestion.

Bob

I can email them to you.  Contact me through the site.

Bob

WB6BYU is right.  The diodes are easy to kill and are much easier to replace using his method.  Here is a link to the manual with the schematic in case you need it.

http://www.mfjenterprises.com/man/pdf/MFJ-949E.pdf

Radio Shack no longer carries the 1N34A diodes.  The NTE equivalent is NTE109, or you can get the NTE110MP matched pair.  Fry's Electronics carries them if you have one nearby.

The MFJ-989D tuner also uses a current xformer and a LM324.  You might look at that schematic since the op amp is still available at Radio Shack.

The 989C uses just the transformer and diodes as shown here:  http://www.mfjenterprises.com/man/pdf/MFJ-989C.pdf

The 989D adds a couple of transistors and an op amp:  http://www.mfjenterprises.com/man/pdf/MFJ-989D.pdf


Bob