TS350 HDV - reduced AM output

[HowBout-cha]

Hi Folks,

First post to the brain-trust. Hoping for some assistance...

I've got a TS350 HDV behind a Lincoln II+. I keep the radio's power low to play nice with the TS350.
SSB does fine (~300 out). AM seems a bit weak.
AM: Barefoot DK ~2w gives me ~50w DK thru the TS - but, only swings to 125-150 max.
...and that's about all it'll put out on AM whether I'm using the TS variable (all the way up), or full power (green switch off).

What could be the issue?

Thx!

PS: Barefoot AM modulation at various RF power levels seems to be in the 4:1 sweet spot.

 

[Shadetree Mechanic]

Welcome! What is the SWR between the radio and amp? On my 350 it was high and I had to make some changes to the amplifier input.

 

[2NC995]

What’s the radio producing without the amplifier?

Mine (Lincoln II+) doesn’t show much on a true peak reading meter, especially with the RF knob dialed down.

I’m running mine into a DX500, and I have only dabbled on AM, and can say for certain that the peak power, especially compared to SSB, was unimpressive.

 

[2NC995]

EDIT: NEVER MIND, below numbers are wrong.

The spec sheet shows 180 out with 4 in. But I believe that’s with AM off. But also shows 20 in to make 350 out.

—————

With your edit:

If you’re at a 1:4 on a peak reading meter, your AM output barefoot would peak at 8 watts with a 2 watt carrier.

Texasstar says 8 watts in should produce 180 out (which I believe is with the am button off)..you’re not far off from the specs.

 

[HowBout-cha]

Wow - quick replies - thx!

I'm trusting my radio's internal SWR meter for measuring the radio to the amp. @ 1w DK input to the TS:
- 1.0 amp off
- 1.2 amp on
I should however, rig a real meter in that location to validate that.

However, SWR does increase as I come up with the Lincoln's variable. @ 2w DK into the TS ( @ full power ~60w out) I'm seeing 1.7 readings - pep here is the 125-150 - so only 2:1ish ratio.
-Also now wondering why I'm seeing that 2w=60w DK in high power mode. I've read that should be more ~50 with 2w in.

My real meter is after the amp.

I seem to get higher SWR values (on the radio) with the TS is in high power mode - even at the same output power from the Lincoln (~1-2w).

I also use it more on SSB, so the AM thing wasn't bothering me much but, I've now gotten to wondering what's up.

The radio alone:
1w DK - low power = 4-5w pep
10w DK - high power = 35-45ish

@ about 5w dk on radio, barefoot, it swings to close to 20 so, i stay just a touch below that when pushing the TS. - couldn't do the 8w DK as you noted as it would drive to hard. I keep it ~3-4w DK input max.

..and yep - barefoot: 2dk = 8w pep

thx!!

 

[2NC995]

I wouldn’t be sick over a 1.7 input, but you could dial it in by adjusting the value of the input capacitor. Your Lincoln has SWR protection that you can set to your desired level.

Out of curiosity, what are you using for a meter?

I run my DX500 at level most would consider very conservative. I set my radio to produce about 12watts peak, and get ~400 from the amp at a little over 40amps draw.

My Lincoln doesn’t seem to compare to most other exports when it comes to AM.

 

[HowBout-cha]

cool - yea, not sick about it - just noting it for the purposes of this thread.

The meter is internal to my MFJ 949E tuner....which is after the TS (obviously).

I've got another meter (Diamond) which i may place between the radio and TS to validate my radio's internal SWR meter.

ETA: Put the diamond SX200 between the radio and TS. It mimics the readings I got earlier. Slight increase when TS is on variable @ 1-2w dk( TS variable on full setting = 1.2:1).
TS on high power bumps SWR up a few points (1.4ish:1) - again, not a huge concern but noting for completeness.


thx

 

[2NC995]

So with the radio at a 2watt carrier, and 8 peak, the amp is showing 125-150 with the AM button on or off?

My radio behaves the same as yours on high power 10:40. But doesn’t go as low as yours, and shows less peak than 1:4 (at the bottom end of the dial).

 

[2NC995]

Also, I would give your other meter a shot and see what it shows. It looks like you’d have to use the very bottom of the scale on the mfj to set the carrier on the radio, and in my experience that can be the least accurate portion of a meter.

 

[HowBout-cha]

I don't have an AM/SSB front button as it's the TS 350HDV. The SSB delay is on the rear (toggle switch) and is enabled - and I run it that way on AM as well - so, i guess the answer to your question is 'off'?
heard there's no issue running them that way....and I'd rather not reach behind it when switching transmission modes.

Yes - the other meter shows similar to the internal for measuring between the transmitter and TS350.

thx!

 

[2NC995]

I was referring to the green button. I think on some it’s called “AM” and on others it just says “Dial a watt”.

Either way, I think what you’ll find is that the amplifier isn’t going to produce anywhere near the same 1:4 out as is going in.

Im sure there are folks showing 300-350 out on am, but I bet their radio is more like a 1:8, or their carrier output is very high and the ratio at output is closer to a 1:2.

if I remember correctly, my radio dialed all the way down is closer to a 1:3, maybe a tad better, and my amp(500) showed less than a 1:2 output on am.

How much PEP on SSB does it take to show the 300w you saw?

 

[HowBout-cha]

ah - ok - yea Dial-a-Watt is normally in use (in/on). That's what I'm considering 'low' power. Dial-a-Watt disabled (button out/off) is what I'm calling "high".

Otherwise, what you're stating seems very similar to my results.

20w PEP SSB is giving me the (real close to) 300 reading.

-just wondering why the big discrepancy between AM and SSB?
-not sure if there's something 'in my radio' that is a bit out of wack on the AM side.
-also wondering that , with my low carrier (~<1w) - why am I showing almost 70w with the TS on high with only 1w in.... thought it was supposed to be more like 50 with 1-2 watts input?...didn't know if maybe I was hitting my AM modulation limiter a bit harder with the bit of a high DK.....therefore not 'swinging' so much on AM.

thx again!

 

[2NC995]

Well....is there a big discrepancy?

Disregard the mode for a moment and just think numbers...20 watts is producing 300, and 8 watts is producing 125-150.

I bet 8 watts SSB would show 125, and 20 watts peak on am would show 300.

And I also bet you’d need between a 1:8 and a 1:10 at the radio to show a perfect 1:4 out of the amp.

I sincerely doubt certain there’s anything wrong with your radio, and think you’re seeing the results of a proper setup into a non-linear amplifier design.

 

[2NC995]

Also, depending on how texasstar has made that amplifier, the Green button may not be a “High/Low”, in fact I don’t think it is.

It is on the DX500V, but if I recall the 500 is unique in that regard. On yours it may just bring the variable into play.

If that’s the case, I imagine the output will be the same regardless of switch position, provided the variable is fully clockwise.

 

[HowBout-cha]

you are correct!!!


The numbers do jive when I equalize them.
To get 300 on AM, the carrier needed (6w - swinging to 18-20) gives me a ~200w DK through the kicker.... swings up to 300ish.
A 200w DK just seems a bit ridiculous off a 6w carrier. - Concerned about equipment damage cuz, I'm a newbie ...and I don't really know what "should and shouldn't be".

-not that i care to do the 300 on AM but, would I be causing any damage with the amplified carrier that high?

but - good lesson learned from the info you gave!
thx!

ETA: Yes, the dial-a-watt just enables the variable pot. I do get a bit more out of it when the pot is disabled (ie: green button off) compared to enabled @ full var power on the TS.