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Better choice for AM than the AL1500. The 3CX1200 tube has a more robust structure, and will not sustain damage from running hot so easily as the 8877/3CX1500 used in their "larger" AL1500 model.
Power gain is only a little less, max output is essentially identical.
73
Power gain is only a little less, max output is essentially identical.
73
What are you guys using as a driver and how many watts to drive the AL1200? Would a 1 or 2 2290 box work with a cobra 1 final radio?
On AM, What kind of deadkey and forward RMS power do your see and as well as PEP?
I assume this amp will do over 1kw Bird (or RMS) from a decent deadkey, I would like to get some figures and or estimates.
Thanks for your time.
On AM, What kind of deadkey and forward RMS power do your see and as well as PEP?
I assume this amp will do over 1kw Bird (or RMS) from a decent deadkey, I would like to get some figures and or estimates.
Thanks for your time.
I run a Palomar blue face tube amp to drive it.It has 4 x6146w tubes in it.Nice driver box the newer version of this box has a rca jack for keying the bigger box.The driver box has 4 drive settings and 3 dead key settings.I run it with some head room so the Ameritron dead keys 350-400 watts and peaking any where between 1800-2200 watts depending on line voltage.
It's a legal ham amplifier, so it requires at least 50 watts of drive for full output. The manual specifies 100 watts, however, and the manual trumps everything. Operated strictly within the limits of the manual it should last forever.
I'd never use it on AM unless it was a real emergency, and I wouldn't drive it very hard at all. It is a "robust" amplifier, but it was designed primarily for CW and SSB, can be used on RTTY and FM, but not AM; it doesn't have the required linearity.
It also doesn't have an RF keying feature like you might be used to. They're illegal for ham amplifiers. I use a footswitch for mine. It's a dual switch arrangement that keys the amplifier just a few milliseconds before it keys the transmitter. Very important to avoid HV transients.
Read and heed the manual. Download it from the MFJ website (you did know that MFJ bought Ameritron, right?
)
I'd never use it on AM unless it was a real emergency, and I wouldn't drive it very hard at all. It is a "robust" amplifier, but it was designed primarily for CW and SSB, can be used on RTTY and FM, but not AM; it doesn't have the required linearity.
It also doesn't have an RF keying feature like you might be used to. They're illegal for ham amplifiers. I use a footswitch for mine. It's a dual switch arrangement that keys the amplifier just a few milliseconds before it keys the transmitter. Very important to avoid HV transients.
Read and heed the manual. Download it from the MFJ website (you did know that MFJ bought Ameritron, right?
)Remember, this amp was designed for SSB at a 33% (approx) duty cycle.
If you run it balls to the wall on AM, it won't last as long. I'm sure Nomad can speak more clearly about this using his SB-220 mods as an example.
http://www.sliderfaq.com/OldNomadWebPages/Zoo/index.htm
If you run it balls to the wall on AM, it won't last as long. I'm sure Nomad can speak more clearly about this using his SB-220 mods as an example.
http://www.sliderfaq.com/OldNomadWebPages/Zoo/index.htm
Master Chief said:
What would be some good AM transmitting tubes than, Something fairly stout that can take the AM abuse...
Toll_Free
Well-Known Member
High Miler said:
If you want complete balls to the wall Am performance, you get a Henry.
Henry uses choke input filtering. Best for AM use. It has more regulation and power capabilities.
Get the 3K Ultra. I had one when they where "new", and loved it.
the 1200A7 tube is MILES better than an 8877. It takes almost twice the drive of the 8877, but has a grid rated (if memory serves me well enough) like 4 to 5 times more.... It can take more abuse, mistuning, etc.
Picture the 8877 being like a sweep tube.. Lots of PEP output, but not very forgiving.
The 1200A7 is more like the 4-1000... Jesus, you just can't beat them up.
Expect in the neighborhood of 4000 CB watts from a 1200A7... Around 2000 to 2250 PEP if run cleanly.
Its about a 13dB gain tube....... I see like 9 to 11 dB out of ones I've built.
--Toll_Free
Sold some of my mobile stuff, in the market for a new tube box.
Are there any modifications to the al-1200 that can be done to make it better for am usage? This box is hard to beat for the price, and would be awesome sitting on my radio table.
Thanks,
Josh
Are there any modifications to the al-1200 that can be done to make it better for am usage? This box is hard to beat for the price, and would be awesome sitting on my radio table.
Thanks,
Josh
It's a great amp I have had one for 6 years now and talk 90% of the time AM with it .No mods needed.Go to eham.net and read the reviews you will be sold on it.
My 8877 Dentron DTR-2000L has been going strong with the same tube now for 13 years at ~1900w pep output.
If you simply do as you're told with regard to tuning an 8877 it will serve you well. I LOVE the fact I only need ~50w to drive it to full legal limit, very easy on the exciter and lower harmonics at that level compared to 100w drive.
Now that I said all that, I'm seriously looking at a Henry, locally, for $1600 and may let my Dentron go for ~$1200, but I haven't yet decided for sure.
I like the way the Henry can be run AM at 1Kw output all weekend long (without unkeying). It's like a small broadcast transmitter! - It's in the cooling; - It's big and heavy, along with being loud & noisy, but it's effective!
If you simply do as you're told with regard to tuning an 8877 it will serve you well. I LOVE the fact I only need ~50w to drive it to full legal limit, very easy on the exciter and lower harmonics at that level compared to 100w drive.
Now that I said all that, I'm seriously looking at a Henry, locally, for $1600 and may let my Dentron go for ~$1200, but I haven't yet decided for sure.
I like the way the Henry can be run AM at 1Kw output all weekend long (without unkeying). It's like a small broadcast transmitter! - It's in the cooling; - It's big and heavy, along with being loud & noisy, but it's effective!