?Been an AMP user for almost 50
years. But have a question.
The Plate/load/coil match the tube(s) output impedance to the
desired antenna impedance typically 50 ohms.
Just like a tuner changes a non 50 ohm antenna to 50 ohms.
But I just thought of this. in the antenna tuner the two caps can
be and usually are all over the place.
And their tuning is typically rather broad. the caps are not super
tight.
But in an AMP
The Plate control is very critical and narrow in optimum setting.
And It's level of "C" is almost predictable. You KNOW the 40 meter
will have less "C" than 80 meters.
And so on through the bands.
The load cap is almost in the same position and in almost every
amp I have had the optimum was rather broad.
Why?
Joe WB9SBD
|
When the amp hangs up on transmit, unplug the rca jack from the amp. If it then unkeys, the problem is not the amp. Test a couple times to confirm. Bob W4JFA
On Sat, Sep 21, 2024 at 11:55?AM Adrian Fewster via <vk4tux= [email protected]> wrote:
Use TX GND & GND? to key
73
vk4tux
On 22/9/24 00:35, Mike Sawyer via
wrote:
Ok
the fellow who gave me the SB-200 to repair now has it in
his possession again with no smoke! However, he said that
the antenna relay is hanging up just like the problem he
has on his AL-80. I know for a fact that it has the
Harbach ‘soft-key’ keying interface installed. The common
denominator is his FTDX-10. I am not familiar with that
rig at all. I understand it is possible to use 2 ports on
the back as a key line. Having said that, is there a
software setting that sets the key line or would keep it
high? He says he has to shut ‘everything’ down before it
returns to normal. I won’t be able to visit his QTH and
examine it myself until sometime in Oct.
?????????
Is there something else I should also check out when I do
go? He is a smart ‘cookie’ but sometimes he can’t see “the
trees for the forest!”
?????????
Thanks in advance.
?
Mod-U-Lator,
Mike(y)/W3SLK
?
?
|
Ok the fellow who gave me the SB-200 to repair now has it in his possession again with no smoke! However, he said that the antenna relay is hanging up just like the problem he has on his AL-80. I know for a fact that it has the Harbach ‘soft-key’ keying interface installed. The common denominator is his FTDX-10. I am not familiar with that rig at all. I understand it is possible to use 2 ports on the back as a key line. Having said that, is there a software setting that sets the key line or would keep it high? He says he has to shut ‘everything’ down before it returns to normal. I won’t be able to visit his QTH and examine it myself until sometime in Oct. ????????? Is there something else I should also check out when I do go? He is a smart ‘cookie’ but sometimes he can’t see “the trees for the forest!” ????????? Thanks in advance. ? Mod-U-Lator, Mike(y)/W3SLK ? ?
|
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 20
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 20
Misc info on how this project goes together.
Bottom of RF deck cabinet will hold the blower, fil xfmr, chain drives etc, etc.
The HV supply will reside in a separate cabinet, with the pair of 150 lb magnespec plate xfmrs, FWB assy, contactors, 20 x 2500uf lytics etc.
|
I experimented making one with a 9v battery. Obviously with the pot adjusted too far one direction the voltage will go toward battery voltage (yes negative). Too high for the 706 or other Icoms. A coin battery would be a safety net for this but it may not last long due to current draw. A battery holder with two AA's?
Jim, there's a reason you made it with a 9v battery though.
Fun little projects.
Bob W4JFA?
Jim, I don't have a 706 but maybe someday. Anyway will the power out on the menu still effect the output power even though the 9 volt battery/potentiometer are on the ALC line?
I have an IC-746 with an RCA jack for the ALC in addition to the ALC on the DIN socket. If this will work for the 746 I'll make?it work with the RCA jack.
Thanks Jim?
Bob W4JFA?
Being curious, will this modification work with the 7300's too?
Andy
On 9/14/2024 1:49 PM, Bob via
wrote:
Jim, I now remember you writing about this a few
years ago. To me this is a serious design flaw. It shoulda went
back to the drawing board. Thanks for writing that again.
So, do you know if the Icom 746 has this spike?
Bob W4JFA?
The 706mk2 puts out a 150 watt spike, regardless of where
you set the PO.? ?The issue with ALC is..... it's closing
the barn door after the horse has bolted....too late to
catch a spike.? ?ALC sorta works ok on xcvrs with no
spike....and only works correctly? if the ALC? time constant
in the amp matches the ALC time constant in the
xcvr.....which never happens.?
One cure for the spike problem is to use a 9 vdc battery and
a 500k? pot.? 9 vdc applied to the extreme ends of the 500 k
pot.? ? Negative voltage comes off the wiper....and is fed
back to the xcvr's? ALC input.? (positive end of
pot / battery goes to the chassis of the xcvr).?
?
Set the pot? for whatever PO? on SSB? you desire.....and
it won't budge.? It can't.? The ALC voltage has now been
derived from the pot.....and is fixed....and is always
sitting there at the XCVR's ALC input.? ?Scream all you
want, and all you will get is say 20.5 watts pep out, that's
it....and no spikes.?
The 706MK2 with it's 150 watt spike will smoke every SS amp
made.? ?Buddy's? Icom? 775DSP was worse.? ?200 watt spike
regardless of where the PO was set at.? ?200 watt spike into
his tube amp was not good.? 200 watt spike every time he
tripped the VOX on ssb.? ?Same deal on the 706 xcvr, 150
watt spike every time you trip the vox on SSB.?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
Jim, I don't have a 706 but maybe someday. Anyway will the power out on the menu still effect the output power even though the 9 volt battery/potentiometer are on the ALC line?
I have an IC-746 with an RCA jack for the ALC in addition to the ALC on the DIN socket. If this will work for the 746 I'll make?it work with the RCA jack.
Thanks Jim?
Bob W4JFA?
Being curious, will this modification work with the 7300's too?
Andy
On 9/14/2024 1:49 PM, Bob via
wrote:
Jim, I now remember you writing about this a few
years ago. To me this is a serious design flaw. It shoulda went
back to the drawing board. Thanks for writing that again.
So, do you know if the Icom 746 has this spike?
Bob W4JFA?
The 706mk2 puts out a 150 watt spike, regardless of where
you set the PO.? ?The issue with ALC is..... it's closing
the barn door after the horse has bolted....too late to
catch a spike.? ?ALC sorta works ok on xcvrs with no
spike....and only works correctly? if the ALC? time constant
in the amp matches the ALC time constant in the
xcvr.....which never happens.?
One cure for the spike problem is to use a 9 vdc battery and
a 500k? pot.? 9 vdc applied to the extreme ends of the 500 k
pot.? ? Negative voltage comes off the wiper....and is fed
back to the xcvr's? ALC input.? (positive end of
pot / battery goes to the chassis of the xcvr).?
?
Set the pot? for whatever PO? on SSB? you desire.....and
it won't budge.? It can't.? The ALC voltage has now been
derived from the pot.....and is fixed....and is always
sitting there at the XCVR's ALC input.? ?Scream all you
want, and all you will get is say 20.5 watts pep out, that's
it....and no spikes.?
The 706MK2 with it's 150 watt spike will smoke every SS amp
made.? ?Buddy's? Icom? 775DSP was worse.? ?200 watt spike
regardless of where the PO was set at.? ?200 watt spike into
his tube amp was not good.? 200 watt spike every time he
tripped the VOX on ssb.? ?Same deal on the 706 xcvr, 150
watt spike every time you trip the vox on SSB.?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
Being curious, will this modification work with the 7300's too?
Andy
On 9/14/2024 1:49 PM, Bob via groups.io
wrote:
Jim, I now remember you writing about this a few
years ago. To me this is a serious design flaw. It shoulda went
back to the drawing board. Thanks for writing that again.
So, do you know if the Icom 746 has this spike?
Bob W4JFA?
The 706mk2 puts out a 150 watt spike, regardless of where
you set the PO.? ?The issue with ALC is..... it's closing
the barn door after the horse has bolted....too late to
catch a spike.? ?ALC sorta works ok on xcvrs with no
spike....and only works correctly? if the ALC? time constant
in the amp matches the ALC time constant in the
xcvr.....which never happens.?
One cure for the spike problem is to use a 9 vdc battery and
a 500k? pot.? 9 vdc applied to the extreme ends of the 500 k
pot.? ? Negative voltage comes off the wiper....and is fed
back to the xcvr's? ALC input.? (positive end of
pot / battery goes to the chassis of the xcvr).?
?
Set the pot? for whatever PO? on SSB? you desire.....and
it won't budge.? It can't.? The ALC voltage has now been
derived from the pot.....and is fixed....and is always
sitting there at the XCVR's ALC input.? ?Scream all you
want, and all you will get is say 20.5 watts pep out, that's
it....and no spikes.?
The 706MK2 with it's 150 watt spike will smoke every SS amp
made.? ?Buddy's? Icom? 775DSP was worse.? ?200 watt spike
regardless of where the PO was set at.? ?200 watt spike into
his tube amp was not good.? 200 watt spike every time he
tripped the VOX on ssb.? ?Same deal on the 706 xcvr, 150
watt spike every time you trip the vox on SSB.?
--
"Where the Old Soo crossed the New Soo"
Duplainville, Wisconsin
Broadcastify Train Scanner:
Youtube Channel:
|
Jim, I now remember you writing about this a few years ago. To me this is a serious design flaw. It shoulda went back to the drawing board. Thanks for writing that again.
So, do you know if the Icom 746 has this spike?
Bob W4JFA?
The 706mk2 puts out a 150 watt spike, regardless of where you set the PO.? ?The issue with ALC is..... it's closing the barn door after the horse has bolted....too late to catch a spike.? ?ALC sorta works ok on xcvrs with no spike....and only works correctly? if the ALC? time constant in the amp matches the ALC time constant in the xcvr.....which never happens.?
One cure for the spike problem is to use a 9 vdc battery and a 500k? pot.? 9 vdc applied to the extreme ends of the 500 k pot.? ? Negative voltage comes off the wiper....and is fed back to the xcvr's? ALC input.? (positive end of
pot / battery goes to the chassis of the xcvr).?
?
Set the pot? for whatever PO? on SSB? you desire.....and it won't budge.? It can't.? The ALC voltage has now been derived from the pot.....and is fixed....and is always sitting there at the XCVR's ALC input.? ?Scream all you want, and all you will get is say 20.5 watts pep out, that's it....and no spikes.?
The 706MK2 with it's 150 watt spike will smoke every SS amp made.? ?Buddy's? Icom? 775DSP was worse.? ?200 watt spike regardless of where the PO was set at.? ?200 watt spike into his tube amp was not good.? 200 watt spike every time he tripped the VOX on ssb.? ?Same deal on the 706 xcvr, 150 watt spike every time you trip the vox on SSB.?
|
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 19
12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 19
The RF deck is finally completed !!
Bias diodes installed.....and also the hb ferrite loaded plate choke. (393 uh, and series resonates at 17.650 hz....and also 30.1 mhz).
A pair of .01uf @ 30 kv disc caps installed at cold end of plate choke...along with a 750 pf @ 15 kv doorknob cap assy. (2 x 1500 pf @ 7.5 kv doorknobs in series). This is a thing of beauty, but was one helluva lot of work + effort. 160-80-40-20-15m....that's it.
Output side has all been mapped out. No padding used on either vac tune or load caps. On the input side, air caps are padded on 160m only. Vac relay's used for the input + bias, and also 2 x more in parallel for the 12 kw output. Everything is rated for 100% duty cycle, brick on key CXR.
Next up is the hb 7500 vdc B+ supply....which gets installed at bottom of the same rack...along with the fil xfmr and Ebm-Papst 330 cfm blower etc. 20 x 2500uf @ 450 vdc lytics will be used in series. (125 uf @ 9 kv)...along with a pair of 7.5 kva CCS identical plate xfmrs, etc.
On a side note, I made up several of those ferrite loaded chokes. On my own choke, I made it a bit longer, and it series resonates @ 16.2 mhz.....and also 27.99 mhz. The 16.2 mhz is midpoint between 20+17m. On Scott's amp, due to height restraints, I had to make the choke shorter..... and his 1st series resonance @ 17.650 mhz is midpoint between 20m + 15m.
Once the B+ and fil supply are built + installed, final testing and calibration can be done.
|
The 706mk2 puts out a 150 watt spike, regardless of where you set the PO.? ?The issue with ALC is..... it's closing the barn door after the horse has bolted....too late to catch a spike.? ?ALC sorta works ok on xcvrs with no spike....and only works correctly? if the ALC? time constant in the amp matches the ALC time constant in the xcvr.....which never happens.?
One cure for the spike problem is to use a 9 vdc battery and a 500k? pot.? 9 vdc applied to the extreme ends of the 500 k pot.? ? Negative voltage comes off the wiper....and is fed back to the xcvr's? ALC input.? (positive end of
pot / battery goes to the chassis of the xcvr).?
?
Set the pot? for whatever PO? on SSB? you desire.....and it won't budge.? It can't.? The ALC voltage has now been derived from the pot.....and is fixed....and is always sitting there at the XCVR's ALC input.? ?Scream all you want, and all you will get is say 20.5 watts pep out, that's it....and no spikes.?
The 706MK2 with it's 150 watt spike will smoke every SS amp made.? ?Buddy's? Icom? 775DSP was worse.? ?200 watt spike regardless of where the PO was set at.? ?200 watt spike into his tube amp was not good.? 200 watt spike every time he tripped the VOX on ssb.? ?Same deal on the 706 xcvr, 150 watt spike every time you trip the vox on SSB.?
|
Thank you Bob. It mentions that radio having a lot of overshoot.
I concluded the amp was functioning as designed, puts out 455W in CW,
which is close to the rating, and if he sets the ALC min-max properly
I figure it will mitigate those errors in SSB. The design probably intends to
limit buckshot / splatter / IMD so it has those paramaters carefully monitored.
Maybe too carefully.
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
E-Mail: Steve@...
toggle quoted message
Show quoted text
----- Original Message ----- From: "Bob" <W4JFABob@...> To: < [email protected]> Sent: Tuesday, September 10, 2024 10:45 AM Subject: Re: [ham-amplifiers] RMItaly BLA600 Steve, Here's some interesting reading on the overshoot issue... ALC Exciter Power Overshoot (w8ji.com) <> Bob W4JFA On Tue, Sep 10, 2024 at 9:10?AM Technotronic Dimensions via groups.io <steve@...> wrote: Hi Bob
Could be...I heard the same thing regarding ICOM but was not sure if
its multiple radios or just the 706.
RMItaly says they only recommend using the ALC jack if you are mostly on 1
band
else if you change bands, you have to reset and re-adj.
The owner of this one only works 6M, so I am gonna have him try and hook
up
the
ALC and set it up in the amps ALC on screen menu. Its got a MIN and a MAX
and (2) trimpots near the RCA jack to set MIN/MAX.
The owners manual is sort of vague for the amp but last night on 80M
I could put no more than about 10W peak ssb mod to it, else it would trip
to sdby with errors that usually indicated the RF input was too much.
Other hams call these "CB AMPS", and those usually are designed with maybe
5-12W inputs from AM or SSB so maybe its working as designed.
Hes running it on 110V power, maybe on 220/240 they would allow more
headroom?
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
E-Mail: Steve@...
----- Original Message -----
From: "Bob" <W4JFABob@...>
To: <[email protected]>
Sent: Tuesday, September 10, 2024 8:44 AM
Subject: Re: [ham-amplifiers] RMItaly BLA600
Steve, I have read that the Icom 706 has a very bad amplifier overshoot. I
wonder if that's what caused the owner's problem?
I don't have any experience with a 706 myself, I've only read about it. I
wonder if your 930 does as well?
Just a thought.
Bob W4JFA
On Tue, Sep 10, 2024 at 8:25?AM Technotronic Dimensions via groups.io
<steve@...> wrote:
Fixing one of these up, had a blown LDMOS FET now
ok on CW, but SSB trips a lot of error protect faults related to I think
the
peak power during modulation input to the amp.
It claims > 25W is what brings it into protect and my Kenwood 930S
trips it in SSB no matter how low the output is. My KW 850S has better
Carrier and FR out controls, so I can bring it down much lower and it
seems to be ok with that rigg.
This is running on 110V hookup, I get about 450W CW carrier,
and most I can see on the average analog power meter is like 200W
and thats almost full bars on the amps power bar meter on the front
panel, so I am left to believe this is its intended operation without
using ALC?
The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I
believe
it does have an ALC output.
I have never ran an amp with the ALC from the rigg, but its suppose to I
guess
limit the spikes I am seeing which also reduces the buckshot side splatter
from the
inherent IMD they produce?
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM <>
E-Mail: Steve@...
|
Steve, Here's some interesting reading?on the overshoot issue...
Bob W4JFA On Tue, Sep 10, 2024 at 9:10?AM Technotronic Dimensions via <steve= [email protected]> wrote:
Hi Bob
Could be...I heard the same thing regarding ICOM but was not sure if
its multiple radios or just the 706.
RMItaly says they only recommend using the ALC jack if you are mostly on 1
band
else if you change bands, you have to reset and re-adj.
The owner of this one only works 6M, so I am gonna have him try and hook up
the
ALC and set it up in the amps ALC on screen menu. Its got a MIN and a MAX
and (2) trimpots near the RCA jack to set MIN/MAX.
The owners manual is sort of vague for the amp? but last night on 80M
I could put no more than about 10W peak ssb mod to it, else it would trip
to sdby with errors that usually indicated the RF input was too much.
Other hams call these "CB AMPS", and those usually are designed with maybe
5-12W inputs from AM or SSB so maybe its working as designed.
Hes running it on 110V power, maybe on 220/240 they would allow more
headroom?
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
E-Mail: Steve@...
----- Original Message -----
From: "Bob" <W4JFABob@...>
To: <[email protected]>
Sent: Tuesday, September 10, 2024 8:44 AM
Subject: Re: [ham-amplifiers] RMItaly BLA600
Steve, I have read that the Icom 706 has a very bad amplifier overshoot. I
wonder if that's what caused the owner's problem?
I don't have any experience with a 706 myself, I've only read about it. I
wonder if your 930 does as well?
Just a thought.
Bob W4JFA
On Tue, Sep 10, 2024 at 8:25?AM Technotronic Dimensions via
<steve=[email protected]> wrote:
> Fixing one of these up, had a blown LDMOS FET now
> ok on CW, but SSB trips a lot of error protect faults related to I think
> the
> peak power during modulation input to the amp.
>
> It claims > 25W is what brings it into protect and my Kenwood 930S
> trips it in SSB no matter how low the output is. My KW 850S has better
> Carrier and FR out controls, so I can bring it down much lower and it
> seems to be ok with that rigg.
>
> This is running on 110V hookup, I get about 450W CW carrier,
> and most I can see on the average analog power meter is like 200W
> and thats almost full bars on the amps power bar meter on the front
> panel, so I am left to believe this is its intended operation without
> using ALC?
>
> The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I
> believe
> it does have an ALC output.
>
> I have never ran an amp with the ALC from the rigg, but its suppose to I
> guess
> limit the spikes I am seeing which also reduces the buckshot side splatter
> from the
> inherent IMD they produce?
>
> --
> Steve Hearns [ KA2PTE ]
> Technotronic Dimensions, VT [USA]
> <>
> E-Mail: Steve@...
>
>
>
>
>
>
|
Hi Bob
Could be...I heard the same thing regarding ICOM but was not sure if
its multiple radios or just the 706.
RMItaly says they only recommend using the ALC jack if you are mostly on 1 band
else if you change bands, you have to reset and re-adj.
The owner of this one only works 6M, so I am gonna have him try and hook up the
ALC and set it up in the amps ALC on screen menu. Its got a MIN and a MAX
and (2) trimpots near the RCA jack to set MIN/MAX.
The owners manual is sort of vague for the amp but last night on 80M
I could put no more than about 10W peak ssb mod to it, else it would trip
to sdby with errors that usually indicated the RF input was too much.
Other hams call these "CB AMPS", and those usually are designed with maybe
5-12W inputs from AM or SSB so maybe its working as designed.
Hes running it on 110V power, maybe on 220/240 they would allow more headroom?
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
E-Mail: Steve@...
toggle quoted message
Show quoted text
----- Original Message ----- From: "Bob" <W4JFABob@...> To: < [email protected]> Sent: Tuesday, September 10, 2024 8:44 AM Subject: Re: [ham-amplifiers] RMItaly BLA600 Steve, I have read that the Icom 706 has a very bad amplifier overshoot. I wonder if that's what caused the owner's problem? I don't have any experience with a 706 myself, I've only read about it. I wonder if your 930 does as well? Just a thought. Bob W4JFA On Tue, Sep 10, 2024 at 8:25?AM Technotronic Dimensions via groups.io <steve@...> wrote: Fixing one of these up, had a blown LDMOS FET now
ok on CW, but SSB trips a lot of error protect faults related to I think
the
peak power during modulation input to the amp.
It claims > 25W is what brings it into protect and my Kenwood 930S
trips it in SSB no matter how low the output is. My KW 850S has better
Carrier and FR out controls, so I can bring it down much lower and it
seems to be ok with that rigg.
This is running on 110V hookup, I get about 450W CW carrier,
and most I can see on the average analog power meter is like 200W
and thats almost full bars on the amps power bar meter on the front
panel, so I am left to believe this is its intended operation without
using ALC?
The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I
believe
it does have an ALC output.
I have never ran an amp with the ALC from the rigg, but its suppose to I
guess
limit the spikes I am seeing which also reduces the buckshot side splatter
from the
inherent IMD they produce?
--
Steve Hearns [ KA2PTE ]
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM <>
E-Mail: Steve@...
|
Steve, I have read that the Icom 706 has a very bad amplifier?overshoot. I wonder if that's what caused the owner's problem? I don't have any experience with a 706 myself, I've only read about it. I wonder if your 930 does as well? Just a thought. Bob W4JFA On Tue, Sep 10, 2024 at 8:25?AM Technotronic Dimensions via <steve= [email protected]> wrote:
Fixing one of these up, had a blown LDMOS FET now
ok on CW, but SSB trips a lot of error protect faults related to I think the
peak power during modulation input to the amp.
?
It claims > 25W is what brings it into protect and my Kenwood 930S
trips it in SSB no matter how low the output is. My KW 850S has better
Carrier and FR out controls, so I can bring it down much lower and it
seems to be ok with that rigg.
?
This is running on 110V hookup, I get about 450W CW carrier,
and most I can see on the average analog power meter is like 200W
and thats almost full bars on the amps power bar meter on the front?
panel, so I am left to believe this is its intended operation without using ALC?
?
The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I believe
it does have an ALC output.
?
I have never ran an amp with the ALC from the rigg, but its suppose to I guess
limit the spikes I am seeing which also reduces the buckshot side splatter from the
inherent IMD they produce?
?
-- Steve Hearns [ KA2PTE ] Technotronic Dimensions, VT [USA] E-Mail: Steve@...?
?
?
|
Fixing one of these up, had a blown LDMOS FET now
ok on CW, but SSB trips a lot of error protect faults related to I think the
peak power during modulation input to the amp.
?
It claims > 25W is what brings it into protect and my Kenwood 930S
trips it in SSB no matter how low the output is. My KW 850S has better
Carrier and FR out controls, so I can bring it down much lower and it
seems to be ok with that rigg.
?
This is running on 110V hookup, I get about 450W CW carrier,
and most I can see on the average analog power meter is like 200W
and thats almost full bars on the amps power bar meter on the front?
panel, so I am left to believe this is its intended operation without using ALC?
?
The owner of the amp uses an ICOM 706MK2 with no ALC on the AMP, but I believe
it does have an ALC output.
?
I have never ran an amp with the ALC from the rigg, but its suppose to I guess
limit the spikes I am seeing which also reduces the buckshot side splatter from the
inherent IMD they produce?
?
-- Steve Hearns [ KA2PTE ] Technotronic Dimensions, VT [USA] E-Mail: Steve@...?
?
?
|
Re: 3CX1200Z7 maximum safe grid current
I use 300 mA as a max at 4kV B+ in CW. The issue with grid dissipation is that the tube’s input impedance needs to be known and it’s not a trivial value to determine. I trust Ameritron’s notation of 300 mA and simply use that
73,
Kim N5OP
"People that make music together cannot be enemies, at least as long as the music lasts."?-- Paul Hindemith
toggle quoted message
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On Aug 14, 2024, at 5:51?PM, Dave w6de <w6de@...> wrote:
? The amplifiers were sold without tubes because they cost too much and killed amplifier sales.The 3CX1200A7 can also be used in place of a 3CX1200Z7.Look here to see the spec sheet of both tubes: https://www.g8wrb.co.uk/triodes/73,Dave, w6de-----Original Message-----From: [email protected] <[email protected]> On Behalf Of John, K9MM via groups.ioSent: 14 August, 2024 21:44To: [email protected]Subject: [ham-amplifiers] 3CX1200Z7 maximum safe grid currentI have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running myAL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube.I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7?Thanks!73,John, K9MM
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Re: 3CX1200Z7 maximum safe grid current
The amplifiers were sold without tubes because they cost too much and killed amplifier sales.
The 3CX1200A7 can also be used in place of a 3CX1200Z7.
Look here to see the spec sheet of both tubes:
73,
Dave, w6de
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of John, K9MM via groups.io Sent: 14 August, 2024 21:44 To: [email protected]Subject: [ham-amplifiers] 3CX1200Z7 maximum safe grid current I have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page 5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running my AL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube. I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7? Thanks! 73, John, K9MM
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3CX1200Z7 maximum safe grid current
I have an AL-1200 with the 3CX1200Z7. The tube has a grid dissipation rating of 50W, but I've found no spec for maximum grid current. On page 5 of the AL-1200 manual it says do not exceed 300ma during normal operation of this amplifier. On page 14 in step 11 of the CW tuning procedure it mentions both 300ma and 250ma. I have been running my AL-1200 at 200ma grid current because I don't want to risk damaging the tube, but I can't get 1500W output on any band at 200ma grid current. I would like to know what is actually the maximum safe grid current for operation of this tube.
I noticed the last time Ameritron was advertising the AL-1200, the price was for an amp without the tube. I took this as an indicator that the tube is no longer in production. Is this true? Is anyone re-building the 3CX1200Z7?
Thanks!
73,
John, K9MM
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So far, so good.? What was the price, including the power supply ??
Tom left Ameritron in 2019.? Dunno who actually designed it.?
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Bob
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