Magnum s9 and tx star 250 hd

[undertaker]

Where should I run the rf power on this radio to run this amp on ssb?

Thanks in advance
Bobby

 

[222DBFL]

SSB has no carrier like am, only modulated power. How many watts pep does the radio do, with that amp I wouldn't push more than 15-20 watts max pep through it. JMO.

 

[magnuman]

You will kill that amp with an S-9 no matter how low you set things.

 

[tba02]

You will kill that amp with an S-9 no matter how low you set things.

I don't know about that. If I can push an RM Italy 503 reasonably with an Optima I would figure a 2 x 2SC2290 can handle 15-20 watts SSB like 222DBFL referenced.
(for reference use ~8 watts PEP on the 503)


I would pretty much ignore the High Drive reference unless in fact the 15 watts in was producing extremely low numbers.

ETA: Yeticom Optima with 16 watts pushes a 4 x SD1446 to 320 comfortably.

 

[BJB]

I don't know about that. If I can push an RM Italy 503 reasonably with an Optima I would figure a 2 x 2SC2290 can handle 15-20 watts SSB like 222DBFL referenced.
(for reference use ~8 watts PEP on the 503)


I would pretty much ignore the High Drive reference unless in fact the 15 watts in was producing extremely low numbers.

ETA: Yeticom Optima with 16 watts pushes a 4 x SD1446 to 320 comfortably.

 

[BJB]

I have been looking for an amp and am willing to purchase a RM Italy. Some reports are that they are rubbish and the TX is splattered.. others say they are good bang for your buck. I have a Uniden Grant ( old school) and also a Magnum s45 HP which I can vary the power enough to run an amp.
I did read that the RM amps when they are even numbered are a better amp than if they end in an odd number...urban myth???.

So are you happy with the 503... power output and clarity of signal. Easy to set up?

cheers Bruce

OZ

 

[222DBFL]

BJB, the RM Italy amps are not bad, the issue most have with using them is over driving them which causes "splatter" and most likely failure. They don't require much power to work properly. a 1-2 watt dead key and about 8-12 watts pep max is all that is needed to power these amps. Your uniden grant would be the better radio to pair with an rm Italy amp, have the dead key turned down or have a variable power installed. The magnum is just too much power even at it's lowest power setting. If you have a bit more money to spend you can get an amp that can be used with either of the radios you mentioned. Something like the tnt 350hd, or a Dave made 2 transistor amp would work well with either radio mentioned. If you use SSB then make sure to have the Dave made amp have an added SSB switch and components. While not cheap like the rm Italy amps, they can take a bit more abuse and keep chuggin along. Another thing I always add is this, if you don't have a good antenna setup, spend the money on that first, get a good antenna, coax, and connectors. A good antenna setup is one of the main overlooked things and can make or break a system. Just my 2 pennies. Good luck and God Bless.

 

[tba02]

Where should I run the rf power on this radio to run this amp on ssb?

I am not sure what the high/low numbers are on that radio, but assuming it can be reduced to 12 watts SSB, that is where I would start.
The Texas Star ratings are here (though I feel they are generous)
- http://www.texasstar.com/export/specifications.html
Note that they list the maximimum input at 20 watts.

The 250 is listed as having 2 x 2SC2290. My research indicates these are 80 watt devices at 27 mhz (not 125 watts like they show in the chart). It also seems they can generally handle ~20 watts PEP input. Using SSB mode I would start around 12 watts and work my way up until I was seeing about 160 watts out - not exceeding 20 watts PEP input.

13.8v*16a=220 watts max possible @100% efficiency.
Based upon 70-75 % efficiency (which some will argue is high), 220 w*.73=160.6 watts.
For me these numbers make sense and come close to what I have seen in real world scenarios.

I am not an expert, I am not a lawyer, just a guy that likes math and stuff.

 

[BJB]

BJB, the RM Italy amps are not bad, the issue most have with using them is over driving them which causes "splatter" and most likely failure. They don't require much power to work properly. a 1-2 watt dead key and about 8-12 watts pep max is all that is needed to power these amps. Your uniden grant would be the better radio to pair with an rm Italy amp, have the dead key turned down or have a variable power installed. The magnum is just too much power even at it's lowest power setting. If you have a bit more money to spend you can get an amp that can be used with either of the radios you mentioned. Something like the tnt 350hd, or a Dave made 2 transistor amp would work well with either radio mentioned. If you use SSB then make sure to have the Dave made amp have an added SSB switch and components. While not cheap like the rm Italy amps, they can take a bit more abuse and keep chuggin along. Another thing I always add is this, if you don't have a good antenna setup, spend the money on that first, get a good antenna, coax, and connectors. A good antenna setup is one of the main overlooked things and can make or break a system. Just my 2 pennies. Good luck and God Bless.

Thankyou for your reply. Although the S45HP can swing high from a low dead key whilst on AM with the so called Top Gun Modulator on, I normally run it on SSB in the standard setting. I can dial down the power to a very low dead key and it doesn't appear to swing very high from that setting. Still too much for one of the RMs????

Bruce

 

[tba02]

I have had very good luck and reports using a KL-503 connected to a Yeticom Optima. I primarily run in SSB mode, so this does not apply to AM> I run 8 watts PEP in SSB mode, variable switch on the KL-503 @ 4 and see about 200 watts output. I rarely have to turn the fan on (but do add a fan). I have always received good reports, no splatter and no TVI - even when using an A99. The KL-503 will draw about 25 amps on average meaning I could run both off of the same 36A power supply. Assuming you can keep SSB output @~8 watts I don't know why it wouldn't work. It is well known that any RM amp that is driven hard will fail.

I think your comment about the even/odd numbers is based on the fact that some RM amps use bipolar transistors, while others like the 503 use MOSFETs.

I know I am probably bucking the trend and most will suggest a true "2 pill" or more - and as already posted I do use a "4 pill" as well with another setup - but thought I would share my personal experience which I have run for about a year w/o issues.

In the end, it's dollars and sense (typo intended)

 

[BJB]

I have had very good luck and reports using a KL-503 connected to a Yeticom Optima. I primarily run in SSB mode, so this does not apply to AM> I run 8 watts PEP in SSB mode, variable switch on the KL-503 @ 4 and see about 200 watts output. I rarely have to turn the fan on (but do add a fan). I have always received good reports, no splatter and no TVI - even when using an A99. The KL-503 will draw about 25 amps on average meaning I could run both off of the same 36A power supply. Assuming you can keep SSB output @~8 watts I don't know why it wouldn't work. It is well known that any RM amp that is driven hard will fail.

I think your comment about the even/odd numbers is based on the fact that some RM amps use bipolar transistors, while others like the 503 use MOSFETs.

I know I am probably bucking the trend and most will suggest a true "2 pill" or more - and as already posted I do use a "4 pill" as well with another setup - but thought I would share my personal experience which I have run for about a year w/o issues.

In the end, it's dollars and sense (typo intended)

Thankyou,

the Texas Star and Dave made aren't readily accessible for us down under ( so I am aware) so we tend to gravitate to what is available and the RM stuff fills the need. My power supply is a 25amp , peak of 35amp. Not sure I could run the amp and the radio from the same PS. You can get PS fairly cheap if you aren't too fussy.

I'm leaning towards getting one of RM units.

cheers

Bruce

OZ

 

[222DBFL]

If you can get the wattage down to around 8-12 watts pep on SSB, it shouldn't hurt the amp like tba02 has said. You must really crank the power down on the optima. I know they will do 60 watts pep on SSB. But I know they can be turned down as far as the power. Just not sure about the magnum. I know my 257hp the rf power has to be all the way up and they say to use the mic gain to control the power. I don't like that.