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I'm interested in buying an Ameritron 811 amp, and would be keying it with my main rig (FT-1000MP MK V), and maybe sometime with my IC-706MKIIG backup rig.

If anyone has used this combination and has any hints or tips on using the ALC (or not using the ALC), I'd appreciate it.

I had a Ten Tec Centaur amp a year or so ago and it didn't require an ALC line - just an output from the keying circuit - but then again, it also had QSK built in.

I use at least 85% CW, but not QSK - I have a slight delay between transmit and receive.

[WB2WIK]

You can use two transceivers with one amplifier just fine.  The 1000MPMKV and 706MK2G probably have different ALC requirements and response, so you'd need to switch the ALC line between the two rigs.  Since the AL811's ALC output port is a common RCA phono jack, you could just use a 2-port (SPDT) RCA phono "switch" to switch this output between the two rigs.

The amp's relay key line can actually be connected to both rigs at the same time if you use a series diode between each transceiver and the amplifier.  The polarity of the diode needs to be: The cathode of the diode connects to the key line output from the transceiver, and the anode of the diode connects to the amp key line input on the amplifier.  Use one diode per rig, so the two anodes of the diodes will be connected together as a common terminal (and the two cathodes are used indepedently, one cathode going to one transceiver, the other cathode going to the other transceiver).  Arranged this way, both rigs can be left connected to the amplifier and either one will key it.  The diodes will isolate one transceiver from the other.  A common 1N4001 (ten cents, anywhere) will work.

WB2WIK/6

[W8JI]

The ICOM has a HUGE interface problems with other equipment. The keying line MUST go through a very low current buffer that triggers at a few volts. If you somehow apply external voltage, you can damage the IC706. If you draw more than a few mA, it will lock the radio up.

The FT1000 is fine, it will key about anything. The MK V is a bit big to drive the AL-811 series however.

This means a simple diode will NOT work. You'll have to build or buy an interface for the 706. Ameritron sells an interface that uses an op-amp, and has a variety of trigger modes. It also will work with ANY amplifier, as long as they require some sort of "pull to ground" to key.

I would not use the ALC, I'd just watch drive settings. The IC706 also has a notoriously bad ALC system. When you run the IC706, it is best to set the gain so you just barely need the ALC.

It reacts even worse to external ALC input.

73 Tom

Thanks very much for the advice. I will pick up an AL-811 and turn the output down on my FT-1000MP MK V and stay with that solution. I use tuned monoband band antennas on 20M (K1WA sloper array) and a half square on 40M. I have avoided using an amp like the plague for the first 290, but I can see that at the bottom of the sunspot cycle a little extra power might make the difference between me getting to 300 or not DXCC wise. What I need now are mostly all fairly rare entities, so the pileups are going to be pretty big.

I won't bother with the IC-706MKIIG - its in my car and I would only bring it in the shack if my FT-1000MP MK V died. But I'll skip trying to drive an amp with it.

[WB2WIK]

That's interesting about the 706M2G.  I don't have an AL-811 (never did) but I do have an AL-80B, and when I had the IC-706 on the bench, it keyed the AL-80B directly with no issues I could find.  Of course, I sold the '706 so I can't easily repeat that test!  (Never did try the ALC...but setting the '706 to 50W output via its menu seemed to be just about right for the amp.)

I sure agree the little AL-811 seems a bit "small" for a 1000MPMKV.  The best-case output power improvement there is only about 4.8 dB, hardly seems worth it.  I'd go for at least the AL-811H, or something a bit more robust than that.  The MKV would have to throttle way back, or be run in its "Class A" mode all the time, to prevent severely overdriving the AL-811...

WB2WIK/6

[WB2WIK]

KY6R, our postings just crossed in cyberspace, so I didn't see yours until just now.

I agree anything that will help, will help most when the bands are rotten, and the condx the past few days surely define "rotten!"

WB2WIK/6

Very good. I had a Ten Tec Centaur driving it with a 100w rig - for a little while (before I went with the MK V). That's why I am looking at the AL-811 - I can run it without running 240 to the shack (which is a major pain in my house).

The difference between the 200W and 500 - 600W will be negligible for everything _except_ when my signal is just barely readable at the DX. A few weeks ago I worked an ET3, but he had to ask me my call so many times that I must have pissed off everyone else who was waiting. We finally made the QSO, but another 400W would have made the difference in how quickly I made the contact. It will make me more efficient in the pileups - I've done very well at getting in the dx-ers passband, but I think the game is different enough during the low portion of the sunspot cycle.

And I have already improved my antennas over my old vertical dipole - which at best had unity gain. The K1WA sloper array is a really cool antenna system at about 4.22 dbi and to of 20 degrees, and the half square on 40M has roughly 3 dbi. So between changing the antennas to gain antennas and adding a little more power, I should be able to work some of the last rare one's that I need. I also loaded the MK V with Inrad filters which really improved this radio. I guess I'd like an FT-1000D better, but oh well.

I've also worked 61 entities with 5 watts - almost all this year, so I guess I enjoy following the old adage - try to use as little power as needed - it keeps things more "competitive" feeling I guess.

[W8JI]

Since I designed the 811, let me give you some advice.

Buy the 811H.

The 811 target goal was to build the cheapest possible amplifier. I had to argue to get a third tube added.

The 811H has four tubes, and is neutralized. It is a much better amplifier.

The weakest link in any of them are the tubes. If the 811's go out, I'd shop for cheap 572's and use them as a replacement.
   

Thanks - the 572B advice sure is sound. But if you cannot run 240 to the shack at all - would you go with the AL-811 or the H and turn down the drive?

[W8JI]

Most wiring will accomodate the 811H and a radio with some accessories just fine. The draw is only about 11 amperes or so at 120V on carrier at maximum power! It is even less when talking.

If you do have trouble tripping breakers, just turn the power down. Everything will last longer anway.
 
I'd just get the 811H.

73 Tom

Thanks for the advice!