Amplifier recommendation

[n4joy]

I am contemplating an amplifier for two meter AM use.  I see two options:

1) Pick-up some old ARRL books from the 50s or scour the net and build one myself.  Problem is I have enough projects on my bench at this point.

2) Simply purchase one; however, I cannot find any reviews or reports of using the FM/SSB solid-state two meter amplifiers on AM.

Any recommendations or advice?  The antenna will likely be a Cushcraft 17B2 or two phased eight element quads up 40'.  Transceiver is a Gonset GC-105.

Thanks,

Chris, N4JOY

[N8ETQ]

  Hey Chris,


     It's hard to beat the 4CX150/4CX250 tubes for
VHF medium power. They have really low drive
requirements and 1 tube will give about 200 w
out, 2 tubes about twice that.

     Some surplus gear out there like the AM-
912/TRC "B" band amp (1 4X150) is a complete
amp for 2 m. and 220. Just whip up a supply
with regulated screen and grid voltage and
hit the plate with anywhere from 800 to 1500v.

    Fair had em a while ago for like $60. they
only need about 5 w drive. Look here for the
dope on these:

http://www.g1ogy.com/www.n1bug.net/tech/am912.html

    Of course all the handbooks have those
"Plumbers Delight" Style. or strip line jobs.

GL Chris,

73

/Dan

[WU2D]

I heartily agree that starting with something is better than building from scratch. Even someones half finished project is a great way to go. I just got a 90% done 6146 amplifier obviously right out of the Handbook, that will take only minor work to be really nice. My ART 13 power supply was a 10 dollar old buzzard power supply with black crackle two meters and a big variac and transformer and a crusty lampcord. Adding a diode stack, bleeders, caps and proper fusing and safety stuff was very simple with so much of the hard stuff done.

[kb3ouk]

A 2 meter FM only amplifier will work for AM, just don't try to run it to the full output that it would do on FM. I've heard of several people who have done it, and it does work.

[n4joy]

I really appreciate the quick reponses--all great information!  I would prefer a tube amplifier over solid state as I like to turn knob.     The simplicity of a solid state FM/SSB amp has its appeal though...  On the Mirage amps, I wasn't sure if the SSB/FM had anything to do with transistor biasing; but this isn't the case as KB3OUK suggests.

I'll let the group know what I decide--building a 4CX150/4CX250 based amp is really appealing.  I'm nervous over the concept of purchasing a Mirage amplifier--too many quality control issues I've been reading about on the net.  I definietly need to ponder this further...

[Pete, WA2CWA]

I would suggest getting the antenna up and doing some operating and listening before contemplating a linear amplifier. Also note that the 17B2 antenna has great gain and a very narrow beamwidth. Not a great antenna for roundtables unless you like spinning the antenna constantly.

[kc4umo]

Not sure if you are wanting to talk with the guys down the street ot if you hunting 2 meter AM DX.
Either way it is like WA2CWA said;

I would suggest getting the antenna up and doing some operating and listening

It is all about the antenna.  As getting into ham radio as a tech I had a blast with the world above 50 MHz.
If you are chasing DX I would go with a Quagi. When I was chacing AM on 2 meters years ago I built a 8 element. It also had a 15 element UHF on the same boom. That antenna worked like a charm. More pics here:
http://www.gokarters.com/vbforum/showthread.php?t=1722

As far as an amplifier you cant beat 2 4CX250B's on VHF

[n4joy]

I appreciate the suggestions.  Yes, my intent is to use the beam for some long distance contacts (intrastate and DX).  I can use a halo or two for the local stuff--assuming there will be any significant interest.  Any mode on two meters is nonexistent in my local area so I'll need to reach out beyond.  Yes, I'll get the antenna up first and go from there.  I recall the quagi from years ago.  Thanks for the link, kc4umo; I will certainly check it out!

Chris, N4JOY

[W3RSW]

An 829b or 5894 makes a nice push pull amp on 2 meters, especially if your using it class C and using external modulation. You don't need strip lines; can use coil and cap tanks, link coupling, etc. I'm not sure what your driving it with so may not be worth the effort if your already at 10 to 25 watts pre modulated and really want a linear.

Agree with trying antenna gain first but some amplification is desirable for rountables for a reason not mentioned.  Many times roundtables are between stations with different polarization on their antennas, esp. On 10 and 6.  Maybe on 2 not so much but still nice to have a decent, quieting signal for the other fellow.

[VE3AJM]

For AM use with plate modulation, its hard to beat the Clegg Zeus transmitter.

Al VE3AJM