Amp question

[Nick23]

Hey guys,

Just a quick question... Can't find a clear answer on the internet. Can you run a radio doing 5w dead key swinging to 20w into a X-force TNT 2 pill? If not that amp, which one could possibly? I know its better to have a lower dead key, but I cant do the mod right now.

Thanks

 

[Crusher]

The TNT 2 pill I think uses the PP100 pills. If that is what is in it, they only recommend 25w DK out of each pill. Meaning that 2 pill should only DK 50w. Now I know these transistors need a bit more drive. But if a 5w carrier produces more than a 50w carrier out of amp, then yes it is too much. That's the best answer I can give.

 

[Crusher]

I have only used the pp100 transistors once and it was to repill an 8 pill messenger. That is the only dealing I have had with them. So I apologize for not being able to be more specific. I'm thinking that 8 transistor amp only needed 15-17w carrier for the 8 to DK like 250-300w. It's been several months. If my memory serves correct, from what I mentioned above. A 2 pill will only need about 2.5-3w Max.

 

[222DBFL]

I would say with a 5w dead key and 20w pep a TNT 600hd would be a better option. It might produce big numbers but rather cruise along and still have plenty of power!! JMHO. The old TNT 350hd with Toshiba 2879's only liked a 2w dead key to see about 50-75 watts of carrier and about 2-300 watts pep depending on the pep wattage. So I would think like Crusher has stated, a lower then 5 watt dead key will be needed for sure with a 2 pill amp. Most likely more like 1-2 watts max. Maybe less to get the amp to key up at 40-50 watts of carrier max.
The TNT 600hd will handle more dead key and 5 watts with these new transistors being used maybe just enough or pretty darn close. Heck I've used my older TNT 600hd with Toshiba 2879's in it with a Uniden 980 and it rocked!! Clean and mean and everything stayed cold!!

 

[Nick23]

Great! I'll start looking at the 600... Thanks for the help

 

[BBB]

Simple layman’s formula for matching radios to linear amplifiers:

Confirm type of pills (bi-polar transistors) in amp.

Confirm max rated output for one pill, before distortion, from data sheet or equivalent.

Divide max rated output of said pill by 4. This is the safe AM dead key wattage for the pill.

Confirm total number of pills in amp.

Multiply the safe dead key wattage per pill by the total number of pills in the amp. This is the safe dead key wattage for the final output of the amp. This 1:4 dead key to max peak wattage ratio is usually optimum for AM.

In AM mode, turn mic gain on radio all the way down. Key the mic. Adjust the RF dead key power output on the radio so as to not exceed the safe max dead key wattage rating figured above for the final *output on the amp. If its too low and/or the radio will not drive the amp to safe max rated power under 100% modulation, the radio is undersized for the amp. If the dead key is too high, other internal adjustments/modifications will be required to the radio to bring the dead key down to a safe level for the amp.

Check SWR at amplifier output with mic gain down and key mic as above. Adjust antenna length/placement so as to not exceed 2:1 SWR.

*Note: All radios and amplifiers will match differently. There are no universal set dead key wattage ratings until the above procedures are followed in the field. A quality calibrated external watt meter and SWR meter are recommended.

**Important: Appropriate power supply rating and interconnect power wiring sizes are required for proper operation. Suggested power supply formula for 2sc2879 (PP100) pills is 20 amps per pill at 13.8 volts DC. Multiply the number of 2879/PP100 pills in the amp by 20 amps and that is the recommended maximum amperage rating of the required power supply. Your voltage may vary

 

[BigKahuna]

Hey guys,

Just a quick question... Can't find a clear answer on the internet. Can you run a radio doing 5w dead key swinging to 20w into a X-force TNT 2 pill? If not that amp, which one could possibly? I know its better to have a lower dead key, but I cant do the mod right now.

Thanks

I used to run both a x-force and a magnforce 2 pill (2879's) and they liked about 2.5 watt -3 watt deadkey with swing from a export radio around 25 watts.

Rather than go to a bigger amp, why not adjust your deadkey - it's a lot easier than trying to wire and set up a big amp.

 

[Nick23]

What would I need? Soldering iron and a swing kit off of eBay? I don't have that much experience with soldering... that's why I was looking at other options.

 

[BigKahuna]

What would I need? Soldering iron and a swing kit off of eBay? I don't have that much experience with soldering... that's why I was looking at other options.

It depends on the radio. What radio do you have?

With most export radios or SSB CB radios it's a simple as turning a pot inside the radio.

If it's a AM only CB radio such as a Cobra 29 it most likely would require doing a little soldering but it's fairly easily - here's one example of the mod although there are quite a few variations - http://cbradiomagazine.com/March 2007/Cobra 29 LTD Super Modulation Modification.htm

 

[Nick23]

Unfortunately, I have a Cobra 29 LX... I wish I could just turn a pot! One thing I'm worried about is in the article on cbradiomag he said;

"Do not do this modification if you are someone who wants clean, clear modulation. Doing this modification to your radio may cause your radio to have bleedover into speakers, neighbors TV's etc."

How bad is it going to be? Is there anyway to counter act this?

 

[space cowboy]

is it a stock 29lx? if so you should be fine no matter what amp you choose to run. if it's not than it's possible they cut the mod limiter in it and you're throwing bad harmonics all over anyway.

 

[Nick23]

No my 29 is not stock. When I had it peaked and tuned I told them not to cut the limiter.

 

[space cowboy]

I'd go with a texas star 350 high drive.

 

[Nick23]

I'd go with a texas star 350 high drive.

With the swing mod or without? Also, when I was looking at the Texas Star the website said a crystal had to be installed to determine the frequency. Where would you get one and how hard is it to install.

Thanks again

 

[n8fgb]

With the swing mod or without? Also, when I was looking at the Texas Star the website said a crystal had to be installed to determine the frequency. Where would you get one and how hard is it to install.

Thanks again

Texas Star are not amplifiers. They are CW transmitters. You pick a frequency in the 10 meter band, and install the crystal for that frequency. Of course if you remove the oscillator circuit, they make a marginally good amplifier.