[TenTec] Low (to no) Power Out Omni D--han'nt given up yet

[Mike Bryce]

Jeez, Scott, hope you don't work as a car mechanic.

You need to set back and think before unsoldering any more parts.

Here's what we know

1. there's no output from the pa
2. there's no output from the LLD
3. You're not pulling current (or very little)

So, you need about 5-12 watts from the LLD into the PA. That's about 1.2 amps, more or less, just for the LLD.

If you can, break the +13 volt feed to the LLD and insert a amp meter. Key the rig. If there is anything less than .500 ma, there's not enough drive. 

Although you said that you replaced just about every part on the LLD, take voltage measurement anyway. The manual has them listed. And don't fret, if they aren't right on the money, they don't need to be, just close.

Now, you're going to need a 'scope. Either steal, borrow, or buy one. 

Just for grins, with your 'scope, check the input to the VFO amp and then the output. You should see gain, more out that in. "The outza gotta be more than the inza."

I don't suspect that as a problem as you didn't mention that the display didn't work and the VFO amp drives the display and the TX mixer.

check for the proper input to the TX mixer. 

There are two transistors on the mixer board. Both are 2N3866 and they have a habit of opening up. Especially the ones from Central semiconductors. 

On the emitter of both are low value resistors. Check them out with your eyes as a burnt or cooked resistor is usually easy to spot. 

You need to have output from this TX mixer to make RF out at the antenna.

DO NOT adjust or mess with any of the trimmers/coils on this board. A screw driver won't fix a broken radio.

Let us know how you make out

mike, wb8vge





On Feb 15, 2012, at 8:52 PM, scottsheppard at videotron.ca wrote:

> Well, the saga continues...in addition to the previous work I have replaced the diodes on the SWR board as well as the TX mixer board no diff.
>