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Author Topic: Drake t4xc to ameritron 811h  (Read 1621 times)
WA1YDH
Member

Posts: 31




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« on: June 12, 2017, 10:39:03 AM »

All
What do i need to do to interface drake t4xc
To 811 h

I dont need alc, just want to trigger the
amp relay,
What external relay do i need? And where
can i get one.

No interest in experimenting,
must someone out there that is doing this

Thanks in advance
WA1ydh
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K4PF
Member

Posts: 6




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« Reply #1 on: June 12, 2017, 06:23:15 PM »


Hi,

You are actually all set to control the amplifier.  Assuming you are using the AC-4 power supply,
the contacts to control the AL-811H are on the AC-4, labeled "VOX".  There will need to be a direct
connection from those contacts to the "relay" terminal of the AL-811H.  The power supply
for the relay coil is within the AL-811H, all it needs is a ground during transmit
for the AL-811H relay to pull in.

Note that no "intermediate" relay is needed, because the relay contacts of the old AC-4/T4-XC
are spaced sufficiently to stand the high voltage relay coils used in the early 1960's,
so won't have any trouble with the AL-811H.

You really should install the ALC line also, to avoid inadvertently overdriving the AL-811H,
which only needs about 60W input. The T-4XC can do about 100W output.
If you don't have the manual for the T-4XC, try http://bama.edebris.com

73,
Ed Knobloch
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WA1YDH
Member

Posts: 31




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« Reply #2 on: June 13, 2017, 05:57:07 AM »

Ok
Have an ac4--what the heck kind of connector
Is on that vox output?

I guess i can wire up to phono plug--
but is that a special drake connector?
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WA1YDH
Member

Posts: 31




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« Reply #3 on: June 13, 2017, 06:16:51 AM »

Thanks everyone
Just ordered ac4 vox cable on ebay

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WB2WIK
Member

Posts: 21737




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« Reply #4 on: June 15, 2017, 09:39:10 AM »

Be careful to not overdrive the AL-811H with the T-4XC.

The T-4XC can output >100W PEP (mine used to do about 125W) and although you can adjust that "down" to lower power on CW, there's no power output adjustment for SSB.    That will badly overdrive an AL-811H, which needs about 80W PEP drive power for "full tilt" output.

I'd connect the ALC to limit this.
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W8JX
Member

Posts: 12039




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« Reply #5 on: June 16, 2017, 05:10:49 AM »

I think it is a bad marriage at start. That old Drake is capable of 125 watts plus out with good finals and fine audio doing it. The Drake was a high quality unit when built too. The AL 811H is a cheap, over-rated light duty amp at best and the 811 tubes in it do not even have twice the rated dissipation of the finals in your Drake. (it is a greatly over hyped amp) That being said I would not bother using that amp with T4xc and depend on ALC to compress RF audio to limit drive and change fine audio of that old rig for a mere 1 S-unit as best. A much better match for that old rig would be a old Heathkit SB220 or Drake L4B or a modern AL82 and all of which have two 3-500's in them and will handle the power output of T4xc without need for ALC compression.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
KM1H
Member

Posts: 2188




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« Reply #6 on: June 18, 2017, 07:22:16 AM »

A good used AL-80B is a far better amp than the AL-811 econoboxes with known poor reliability.

And the 125W drive capability of the T4XC is a real fact....I ran a pair of C Lines for many years while contesting.  A small, quiet muffin fan on top of the final cage will do wonders for tube life as excessive tuning and the heat can quickly destroy them.

Carl
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VR2AX
Member

Posts: 799




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« Reply #7 on: June 19, 2017, 05:33:49 AM »

I think the focus back then was input not output power. They were rated 200 watt input. The TR4 series had special instructions on how to reduce power from 300 watt input because that would even damage the L4 series and similar.
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W8JX
Member

Posts: 12039




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« Reply #8 on: June 19, 2017, 12:02:11 PM »

I think the focus back then was input not output power. They were rated 200 watt input. The TR4 series had special instructions on how to reduce power from 300 watt input because that would even damage the L4 series and similar.

Those made close to 200 watts out and that was too much for a L4B
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Ham since 1969....  Old School 20wpm REAL Extra Class..
VR2AX
Member

Posts: 799




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« Reply #9 on: June 20, 2017, 04:51:27 AM »

I think the focus back then was input not output power. They were rated 200 watt input. The TR4 series had special instructions on how to reduce power from 300 watt input because that would even damage the L4 series and similar.

Those made close to 200 watts out and that was too much for a L4B

Agreed but way ahead of the time then. Pity one can't re-run.
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W8JX
Member

Posts: 12039




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« Reply #10 on: June 20, 2017, 09:02:29 AM »

I think the focus back then was input not output power. They were rated 200 watt input. The TR4 series had special instructions on how to reduce power from 300 watt input because that would even damage the L4 series and similar.

Those made close to 200 watts out and that was too much for a L4B

Agreed but way ahead of the time then. Pity one can't re-run.

Those old Drakes had fine audio with great dynamic range in xmit audio. I would not mess it up by hooking it up to a cheap 811 amp.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
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