What To Do with an EB-63?

[AD6KA]

Quite a few years ago I built an EB-63 SS amp (~140w)
from CCI (2 X MRF 454). The intention was to use it
with various CW, PSK and SSB QRP rigs. I built the
K5OOR "100 watt Low Pass Filter Board" kit, but really,
those inductors are just too small, too close together,
and get wayyy too hot. It's really not for 100w use.
But there are other LPF boards and circuits out there
for me to research.

But much more importantly, I have since learned from reading these
amp blog boards that the EB-63 is not linear, has no real
bias control circuitry except a big clamping diode, operates
strictly Class C and has horrible IMD performance. (I have
learned a lot from reading the "gurus" on these boards.)

So...what am I to do, if anything, with this amplifier?
IS THERE a way to build in proper bias control, or should
I just say "Lesson learned, oh well", throw in the towel,
and use the parts for a better amplifier design?
Just operate Class C CW? (With the proper LPFs of course).
Would the IMB be acceptable at lower power, say 50w?
(I have no equipment that could test this)
I'd never sell it to a non-ham or CB'er, and probably not
even to a ham who doesn't plan on fixing the IMD issue.

Suggestions? Ideas for a good bias control circuit to add?
Or chock it up to lesson learned and start over?
TNX ES 73, Ken AD6KA

EB63-A.jpgEB63-B.jpg

[AC4LJ]

Ken, I have been bitten by the bug to build a solid state amplifier. Choices seem limited, but I have been looking at the amp described in Motorola's AN 762. This appears to be the same amp as the eb63 with improved bias control. The problem I now find is availbility of parts .... This may be taking the thread off topic, but may show you an option. 73 Tony AC4LJ

[AD6KA]

Thanks Robert:

Yes, it looks like the AN-762 is what I should have bought
in the first place! Since a friend with a machine shop made,
drilled, and tapped a nice heat sink and sheet metal "Fan Air
Flow Director", it sure would be nice if the AN-762 PC board
lined up with, the mounting holes on the EB-63. (Or at least
left me room to drill and tap new holes).

Oh, and an FYI to those thinking of buying an EB-63:

What CCI is now shiping is the EB-63A. You do NOT get
what you see in the photo or description on the CCI EB-63 web page.
They charge you for a large DPDT open frame relay, but you get a
small $3 PC board mount relay. Also the board layout and schematic
are slightly different, and the traces on the board much, much narrower.

I don't have one of these "EB-63A's" but have seen good photos.
I wonder what OTHER changes CCI has made to their products
that they are not revealing on their website.

Oh well, live and learn. I just wish There was a good "bias fix"
for this amp without having to rebuild the entire amp.......
but as the old saying goes "If wishes were horses, beggars would ride!".

tnx agn es 73, Ken AD6KA

[W9GB]

Ken -

FoxDelta offered a board, based on Helge Granberg's, K7ES(sk) design & DIY build in the
1981-1983 ARRL handbooks (based on his AN-762 Application Note).
http://www.foxdelta.com/products/rfa...81-6-41-43.zip

The LM-723 is on the PC board for voltage regulation (bias).

Your MRF-454 transistors will work on this PC board !
http://www.foxdelta.com/products/mrf455.htm

w9gb

[AC4LJ]

Greeting all .... FoxDelta is sold out of these "kits" with no plan to re stock. CCI is apparently no longer in business. Where's a feller to go? any ideas Tony AC4LJ

[W9GB]

Greeting all .... FoxDelta is sold out of these "kits" with no plan to re stock.
CCI is apparently no longer in business

TONY --

I would HIGHLY suggest you check your facts, before stating the business status
of an amateur radio dealer.
Your statement about Communication Concepts, Inc. (CCI) is INCORRECT.
I just got off the telephone with CCI, and they were not happy reading your statement on QRZ.

Communication Concepts, Inc. (CCI) IS OPEN for business.
http://www.communication-concepts.com/

For further information or to place an order please contact CCI via the following methods.
Telephone: 937-426-8600
Fax: 937-429-3811

Communication Concepts, Inc.
508 Millstone Dr.
Beavercreek, OH. 45434-5840
E-mail: cci.dayton@pobox.com

AN-762
http://www.communication-concepts.com/new_page_10.htm
===

Where's a feller to go? any ideas Tony AC4LJ

The ARRL Handbooks and Motorola Application Notes have Helge Granberg's work and PC board layouts. However, these designs and components are ~ 30 years old.

Newer RF transistors (LDMOS) have been introduced by Freescale (an old Motorola division), but boards, and kits are not yet available or offered.
http://www.freescale.com/webapp/sps/...eId=0106B97520

IF you desire solid-state, the Elecraft KPA-500 Kit provides an excellent solution for $2,000 USD
http://www.elecraft.com/KPA500/KPA500.htm

For cheaper, you are left with repairing (restoring, or scrounging) older tube and solid-state designs.

[K1ZJH]

Quote: I'd never sell it to a non-ham or CB'er, and probably not
even to a ham who doesn't plan on fixing the IMD issue.


What do you want for that board? I might be interested in attempting to save it.

Pete k1zjh (amateur extra and FCC 1st class radio)

[KO6WB]

If the amplifier is truly running in class C you can operate it on more modes than just CW. You can run RTTY and Data and of course FM. Any mode that has 100% duty cycle is okay on a class C amplifier.
The modifications to bring an EB-63 to full linear operation isn't that much of a change. Do as Greg has suggested and use the bias network out of the ARRL Handbook. You can make it on a small seperate board and just tie it into the base circuit of the EB-63.
73
Gary

[AC4LJ]

World... I aploigize to CCI and all on the forum. CCI is intact and doing well. I just ordered (over the phone) the AN 762 amplifier kit. The problem was internet involved. Thanks for bringing this to my attention, W9GB, All is well now Tony AC4LJ

[AD6KA]

Thanks for all the great advise guys!

Do as Greg has suggested and use the bias network out of the ARRL Handbook.
You can make it on a small seperate board and just tie it into the base circuit of
the EB-63.

Sounds like a plan, if I can pull it off without toasting those 454's.

K1ZJH:
What do you want for that board?
I might be interested in attempting to save it.

I dunno Peter, lemme do some bias circuit research advised by
the other helpful fellows. The one in the photos is perfectly
laid out to easily drop into an enclosure with another project.

However I have an even older EB-63 already mounted in a decent enclosure
with a breezy squirrel cage fan and a 25A circuit breaker switch.
I might let that one go more easily. Haven't checked it out it in years but
it should work FB. (It too is without LPF's).

But I will keep your email in case or when, I decide to let it go.
TNX AGN TO ALL.
73, Ken AD6KA