|
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@...?
?
?
|
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, 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@...
>
>
>
>
>
>
|
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@...
|
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.?
|
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.?
|
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 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:
|
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:
|
Technotronic Dimensions
Bob