Texas Star DX 350HDV transmit/keying issue

[Lkaskel]

Hi Gang,
I recently picked up a mint condition DX 350HDV. I have it connected to my Teaberry Stalker XX that is set to stock power (4AM and 12SSB) and the modulation is at 100%. I am using an Astatic 575 mic. When using it on side band it does not consistently key up the amp . It does at times key it but when it does it may miss the beginning of the transmission. I do have the SSB/delay switch turned on and it does delay when the transmission stops as it should. I know that this is a high drive amp but the specs seem to indicate that my radio should key it fine. I have tried it with a few other radios with similar results. Also, when I have used other amps this was not an issue. Any thoughts?

One last question. The amp has 2 large variable caps in it. I am assuming that this is for tuning but I could not find any detail or an alignment process.

Thanks as always!!!

 

[2NC995]

It's not really a high drive amp. That's some Texasstar mumbo-jumbo for marketing.

12 watts input will do just about all she'll do. In fact, a 4 watt carrier is too much.

What you're seeing with the SSB transmission is a product of RF keying. The keying transistor won't turn on the relay until it receives power from the radio...and being no carrier on sideband, it just won't do anything until you start talking.

If you were running a noisy mic, either with background modulation or a noisy switch, you probably wouldn't notice it.

 

[9C1Driver]

I would agree with everything 2NC995 said. Lkaskel, what ever those caps are that you saw leave them alone. There is nothing for the user to "tune" on a Texas Star amplifier. On AM it's simple, you key the mic and the AM carrier keys the relay. On SSB the amp won't do anything when you key the mic. When you talk the relay in the amp will key, the SSB delay will hold the relay open in between words. If you ran SSB with the delay switch off the amp would constantly click while talking.

 

[AudioShockwav]

Can you post a few pictures of the inside of the amp?
Right off the bat there should not be any variable caps in a TS 350 unless some one has added them.
Texas Star amps have fixed tuning.
Pictures may tell a story.
If the amp is operating properly it should key the same on SSB every time, not just sometimes.
Do you have the variable knob full open?
Does it change when it in in a different position?

73
Jeff

 

[nomadradio]

If you have a radio with a carrier-control knob, you could try to judge how sensitive the keying circuit is.

Turning the carrier down to a quarter of a Watt should not cause the amplifier to drop the relay.

If it does, it won't be sensitive enough to kick in on sideband reliably.

And if you need a full Watt or more carrier to make the relay kick in, that's the root of the problem.

Just about have to put a meter between the radio and the amplifier to tell this.

One accurate measurement is worth a thousand expert opinions.

73