Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Do I purchase the Ameritron AL 80B or the AL 80 BGOP ( Grid protection)  (Read 4546 times)
VE3BXB
Member

Posts: 34




Ignore
« on: February 16, 2011, 07:38:13 PM »

I am about to purchase an Ameritron amplifier (AL 80B) I see that one of the models "Includes Factory Installed Grid Protection"  Is it worth the extra  $70 to have this feature.
The basic model is obviously cheaper to purchase but I really don't know  whether I should spend the extra cash or not.   What do you think.?.  All comments would be appreciated.
Bob VE3BXB
Logged
KM3F
Member

Posts: 523




Ignore
« Reply #1 on: February 17, 2011, 01:12:36 AM »

I run an 80B and cannot see a real reason to have the extra protection.
When tuning up you can drive the grid pretty hard at 100 watts in but the 3-500 should take it without a problem over the long term if not tuned any great length of time in one shot but multiple short tunes to arrive at peak power out.
After words, using ALC feed back set to limit grid current to some reasonable level allows your use full 100 watt drive without danger to the tube.
As well, the amplifier has auto bias control as a normal feature.
Combined, these still allow peak envolope power to be hit while keeping the average grid dissipation low.
Again what does the extra protection buy you in "practical" terms?
If the tube goes gassy or arcs over, you still have an issue with or without it.
I'm not saying grid protection does not work but am saying if it is enough of a benefit.
$70 is not a lot of money for an option if it makes you feel better.
Good luck.
Logged
VE3BXB
Member

Posts: 34




Ignore
« Reply #2 on: February 17, 2011, 02:49:48 AM »

With regards to the previous post, you make a comment concerning ALC  feedback.  I have beem reviewing the owners manual for the AL 80B and I see the following text on page 13 where it says the following.

6. Connect the "ALC" jack to the ALC input of the exciter with a shielded cable and an RCA phono
plug.  The proper connection point on the exciter should be indicated in the exciter's manual. 
The AL-80B ALC will operate with any exciter that uses a negative-going ALC voltage of up
to 10 volts.

I am curious to know if you have hooked up any ALC cables between the exciter and the amplifier.  I hear that some people do not bother with this ALC connection and I sometimes wonder why this is the case.  I am currently using a Yeasu FT 950 and I see that I have no RCA phono plugs on the back of the unit that connects to the amplifier.. I somehow would assume that I could use an ARB 704 interface device between the radio and the amplifier in order to help me make the necessary connections including ALC control. Please keep in mind that I will be using an optional Yaesu cable that has a mini din connector and open wires on the other end. I would think that I would somehow solder an RCA phono plug on the open end of this cable  So the bottom line is, do you need ALC control connections coming from the exciter to the amplifier.?

If there are no ALC exciter cables hooked up, I would assume that you can still have manual control of the ALC with the use of the front and rear panel ALC controls. Is my assumption correct?  I get the impression that with manual ALC control without the exciter cable hoop up, you can still safely control the ALC and therefore keep the grid current of the tube with in specifications   Does this make any sense?

I just want to say that I have never owned  or operated an amplifier so I am being cautious to make sure that I make the right decisions with regards to when I do purchase my first amp

Thank You
Bob VE3BXB
Logged
K3PRN
Member

Posts: 25




Ignore
« Reply #3 on: February 17, 2011, 07:53:37 AM »

I own an AL-80B and see no reason to purchasing the grid protection. Just monitor grid current when tuning the amp. I purchased a used, extremely clean AL-80B for $850 and would suggest looking for a used one rather than new. The cost savings can be used fort a dummy load etc.

73,
Don K3PRN
Logged
KA5N
Member

Posts: 4380




Ignore
« Reply #4 on: February 17, 2011, 10:39:51 AM »

Some transceivers have a built in ALC that allow one to set the final output wattage and the ALC will control the level quite well.  Other transceivers don't have this feature or have it and it doesn't work very well.  If you don't have some sort of ALC you can easily overdrive the amp and cause all sorts of problems.
It is incumbent upon the operator to learn enough about his equipment to know how to operate it properly.  If you can't get what you need by reading then find a more experienced ham to go over your setup with you and make sure you have your equipment set up correctly and know how to operate it.
Allen
Logged
WB2WIK
Member

Posts: 20636




Ignore
« Reply #5 on: February 17, 2011, 11:56:40 AM »



I am curious to know if you have hooked up any ALC cables between the exciter and the amplifier.  I hear that some people do not bother with this ALC connection and I sometimes wonder why this is the case.  I am currently using a Yeasu FT 950 and I see that I have no RCA phono plugs on the back of the unit that connects to the amplifier.. I somehow would assume that I could use an ARB 704 interface device between the radio and the amplifier in order to help me make the necessary connections including ALC control. Please keep in mind that I will be using an optional Yaesu cable that has a mini din connector and open wires on the other end. I would think that I would somehow solder an RCA phono plug on the open end of this cable  So the bottom line is, do you need ALC control connections coming from the exciter to the amplifier.?

Yes, you do that, yourself.


Quote
If there are no ALC exciter cables hooked up, I would assume that you can still have manual control of the ALC with the use of the front and rear panel ALC controls. Is my assumption correct?  I get the impression that with manual ALC control without the exciter cable hoop up, you can still safely control the ALC and therefore keep the grid current of the tube with in specifications   Does this make any sense?

Nope.  It doesn't work that way.  ALC is a dumb output from the amplifier.  When connected to your transceiver, the amplifier becomes an extension of the rig's ALC control loop, but the amplifier provides the signal to the transceiver telling it what to do.  Without this connection, the ALC controls on the AL-80B do absolutely nothing at all.  I definitely use the ALC connection with my AL-80B, when connected to a transceiver that provides an ALC input.  It works, and works very well.  But again, unless you make this connection, the ALC circuit and the controls on the amplifier do absolutely nothing.


Logged
KM3F
Member

Posts: 523




Ignore
« Reply #6 on: February 17, 2011, 06:36:40 PM »

Steve is right on about the ALC operation.
I use the ALC to make my overall operation more fool proof, to gain some measure of RF power compression for DX work and to control carrier power when operating AM mode.
I limit the power output to no more than 100 watts on AM with full 25 watt drive and watch the plate color vs transmit time as a way know when to turn the QSO back to the other station.
In this mode, a 100 watt carrier will drive the amplfier to 400 watts at 100% modulation.
So the duty cycle is quite high for a single 3-500 on AM so it has no what is called "headroom" such that you must watch key down time for.
The tune-up for AM is the same as SSB, full smoke to keep the amplifier the cleanest on modulation peaks. even through the carrier is set at only 100 watts.
The tube in my amp still makes full 1000 watts for 100 in so the tube has not suffered any degredation as of yet.
Logged
VE3BXB
Member

Posts: 34




Ignore
« Reply #7 on: February 18, 2011, 05:47:12 AM »

I see from one of the previous post's the following was stated.   "  It works, and works very well.  But again, unless you make this connection, the ALC circuit and the controls on the amplifier do absolutely nothing"

For sure I will be hooking up the ALC lines between the amp and the radio with the ARB 704 in between.  I know that I don't need to have the use of the ARB 704 but I will use it for insurance purposes.  On that note I have to say that I am using the Yaesu FT 950 rig.  I have ordered the T9207451 interface cable that uses a min din plug on the back of the FT 950   Now I am trying to figure out what type of connection I should be using to hook up to the ARB 704  I don't have the 704 or the amp as of yet but the dealer is out stock. In the meantime is there anyone out there that has plugged an FT 950 to the ARB 704 and then to the amp.  What kind of plug do you use on the end of the interface cable that comes from the back of the FT 950   You have the mini din plug on the radio end but what kind of plug goes on the other end of the interface cable that plugs into the ARB 704?  Any ideas.  Thanks   Bob
Logged
W9PMZ
Member

Posts: 575


WWW

Ignore
« Reply #8 on: February 18, 2011, 05:54:07 AM »

"ARB 704 but I will use it for insurance purposes."
and will you add an ARB 704 to protect the ARB 704 and on and on?
paranoia reigns supreme...
Logged
WB2WIK
Member

Posts: 20636




Ignore
« Reply #9 on: February 18, 2011, 09:01:37 AM »

I see from one of the previous post's the following was stated.   "  It works, and works very well.  But again, unless you make this connection, the ALC circuit and the controls on the amplifier do absolutely nothing"

For sure I will be hooking up the ALC lines between the amp and the radio with the ARB 704 in between.

The ARB-704 is just a connection point for ALC, it does absolutely nothing to the ALC line except pass it in one jack and out another.

Quote
I know that I don't need to have the use of the ARB 704 but I will use it for insurance purposes.  On that note I have to say that I am using the Yaesu FT 950 rig.  I have ordered the T9207451 interface cable that uses a min din plug on the back of the FT 950   Now I am trying to figure out what type of connection I should be using to hook up to the ARB 704

Ameritron sells "plug & play" cables for the ARB-704.  Get the one for the Yaesu ($17.95) and you're done.  It plugs into the ARB-704 on one end and the FT-950 on the other end.  Then you just use the already-supplied RCA patch cables to connect to the amplifier's ALC out and RLY ports.



Logged
N5YCN
Member

Posts: 2


WWW

Ignore
« Reply #10 on: February 18, 2011, 10:58:46 AM »

Bob, I agree with Ken, KM3F.  Unless you are planning on driving the amp with an exciter that produces over 100w drive, there is no need to worry about the the ALC hook up.  You are able to adjust the power out on the FT-950.  Dial it down to about 90w drive and tune the amp for maximum power out.  You will do just fine.  As far as the extra Grid protection, as long as you pay attention to what you're doing I just don't see any need for it.  I told you you would get really confused reading the manual from Ameritron.  The AL-80B is quite robust and very forgiving.  I don't think you'll hurt it!  Even as you are learning to use it.  Once you tune the amp a few times, you'll realize it isn't nearly as hard as the manual makes it out to be!  When you get the amp, if you have any questions or concerns, give me a call back.  I'll be glad to help you get it on the air.  Tim  N5YCN
Logged
WB2WIK
Member

Posts: 20636




Ignore
« Reply #11 on: February 18, 2011, 01:24:34 PM »

Bob, I agree with Ken, KM3F.  Unless you are planning on driving the amp with an exciter that produces over 100w drive, there is no need to worry about the the ALC hook up.  You are able to adjust the power out on the FT-950.  Dial it down to about 90w drive and tune the amp for maximum power out.  You will do just fine.  As far as the extra Grid protection, as long as you pay attention to what you're doing I just don't see any need for it.  I told you you would get really confused reading the manual from Ameritron.  The AL-80B is quite robust and very forgiving.  I don't think you'll hurt it!  Even as you are learning to use it.  Once you tune the amp a few times, you'll realize it isn't nearly as hard as the manual makes it out to be!  When you get the amp, if you have any questions or concerns, give me a call back.  I'll be glad to help you get it on the air.  Tim  N5YCN

It is a pretty robust amp.  I've repaired a few (never my own -- which has worked perfectly since it was new over 10 years ago) for others, and in every case damage was caused by cockpit error e.g., turning the bandswitch while transmitting (!) or badly UNDERloading the amplifier and then overdriving it.

I use the ALC for sure when driving it with my TR-7, since the TR-7's output is only adjustable for carrier modes and not for SSB, and it can run well over 100W output on voice peaks.  With the ALC connected, it throttles back to 60-70W PEP output and keeps the Ig down under 150mA peak (meter actually reads almost nothing during normal speech, if the amp is loaded properly), and the interesting thing about the ALC is it improves "punch" a great deal.  PEP doesn't change, but average power is dramatically increased with the ALC connected and adjusted.  Simply plugging in the ALC cable during the course of a contact usually elicits a comment like, "Wow, you're so much louder now!" when all I did was activate the ALC.  Watching the PEP wattmeter, there's no change.  With an average reading meter, there is.

It's a good circuit that actually works with most modern rigs -- and works spectacularly well with my 1978 vintage TR-7.
Logged
W6HB
Member

Posts: 38




Ignore
« Reply #12 on: February 23, 2011, 01:52:34 PM »

IMO the GOP is inexpensive protection for those days when mistakes are made.

Yaesu advises that the ALC interface is not required between the AL-80B and an FT-950.

Doug:
Because the FT-950 cannot exceed 100 watts, you do not have to worry about ALC.  However it is good practice to use a relay between the radio and the amplifier.  Ameritron makes the ARB704 relay for this purpose.
 
73
Tim Factor, KT7F
Amateur Radio Technical Support

Vertex Standard USA, Inc.
Yaesu Amateur Products Division
10900 Walker Street
Cypress, CA 90630
t.factor@vxstdusa.com

714-827-7600 x 1513


-----Original Message-----

73 - Doug - W6HB
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!