have MFJ-949E

[rbig]

I've got an MFJ-949E. It's an older antenna tuner. Sat in the closet for years. Got it out the other day and trying to get it to work on.

The reflected power can certainly be minimized. Seems to tune good.

Problem is that there is no forward power.

This is one of those small circuits which have a couple of 1N34s in them, and should read both reflected as well as forward power.

My forward power stays on zero.

Is this likely a 1N34 deal where I should change it and maybe get forward power back?

 

[RatsoW8]

Just call MFJ and they will send you replacement diodes for free. It's been a while since I changed them in my 948 but the replacement diodes are still going where I used to chage them out every few months.

 

[wavrider]

That or the meter movement is bad in the meter.

Ohm the coil and see if it is open.

MFJ does still sell replacement meters for that tuner.

Look in online catalog.

 

[rbig]

Not the meter. I think 1N34A is bad.

Would ya believer it? Radio Shack does not show a 1N34A !!!!! Is there anything close to it that would work OK I might find at Rat Shack???

 

[TonyV225]

1N34A | eBay

 

[wavrider]

Not the meter. I think 1N34A is bad.

Would ya believer it? Radio Shack does not show a 1N34A !!!!! Is there anything close to it that would work OK I might find at Rat Shack???

Rat shack has become the cell phone people, at least in this area.

Tony sent you as link for fleabay, other sources may be digikey, mouser electronics.

 

[RatsoW8]

Rat shack has become the cell phone people, at least in this area.

Tony sent you as link for fleabay, other sources may be digikey, mouser electronics.

Actually MFJ send me what look like small signal schottkys to replace the original germaniums and they have been good for over four years running up to 250 watts. I have a bunch. If you PM me your address I'll mail you a few. And yes, if the left needle is moving an the "forward" side isn;t that classic rf sensing diode failure in the MFJ 300 watt tuners.

 

[Beetle]

That or the meter movement is bad in the meter.

Ohm the coil and see if it is open.

MFJ does still sell replacement meters for that tuner.

Look in online catalog.

If by "ohm the coil" you mean to "connect an ohmmeter to it", that's a very risky move. A typical ohmmeter can provide more than enough current to burn the coil up within milliseconds. Then, of course, it WILL be open.

Take a 100K resistor and clip it to one of the test leads and use the free end of the resistor as a test probe. Just check for movement of the pointer, not for a specific reading. The resistor will help protect what might be a perfectly good meter movement.

 

[rbig]

I think meters all right. It moves a bit on occasions. Just a slight upward blip.

I can still use the tuner OK by minimizing reflected power, can't I?

 

[C2]

yes