It is prudent to reduce your TX power for the lower bands - especially if the
antenna is short. The RF voltage on the output part of the tuning circuit can
get pretty high at lower frequencies, and there is an increasing risk that the
relays could be damaged.

Take a look at the schematic for an SG-235 - a tuner rated for 500 watts. 
http://www.sgcworld.com/Publications/Manuals/235man.pdf

Note the output shunt capacitors - each one is placed into the circuit by FOUR
relays - connected in SERIES! Each of the relays contacts have a small, but
still significant resistance, and stacked together in series, they act as a
voltage divider, dividing the output RF voltage equally among the 4 contacts,
and therefore not exceeding the maximum voltage rating of any one relay.

Again, the RF voltage that these relays, and all of the other components on the
output side of the circuit - are exposed to, tends to go up as the frequency
goes down. The problem is compounded when your antenna length is short.

It seems reasonable to conclude that a longer antenna (within limits), coupled
with a first rate ground system (good is never good enough!) will reduce this
problem, and allow you to operate at higher power.

Having said that, keep in mind, even when the unit has found a match, the bridge
circuit is still exposed to the RF you generate. It can only take so much...

73s - Steve KG4LJB

I am trying to interface the sgc237 with a TCI-1 controller running an Icom
ic-7000.

Pressing tune causes the autotuner to ligth a bulb and show the tuned  leds
which is in the smartuner.
The TCI-1 fault light stays on and the tuner times out at 30 seconds. The
Ic-7000 goes to tuner bypass mode.

I checked the Tuned line from the tuner and it doesn't drop down to zero volts
like it should. This is needed to tell the radio that all is ok through the
interface.

Does anyone have a schematic for the SGC237 or have a good idea which parts have
been smoked? In other words has anyone been there done that>
Jim n2go

 

Yes, that was a great response by Steve.

On the 80W CW limit, I don't know what duty cycle is assumed, but what I do know is that I have, not once, but twice, exceeded the 80W limit and blew out the RF tuning sense diodes. The first time, I thought it was lightning, or some other random event. The 2nd time, I got to thinking about what I did and realized I was running well over 100w CW trying to get through to a dxpedition.

I had not read the manual carefully enough, and did not know that CW was limited to 80w. The tuner is rated to handle 200w at SSB duty cycle, which is what, maybe 30%? So, that would imply on CW, better keep the power below 80W if you a pounding out a lot of code. It is not like you are burning up some device that is designed to handle power, these are tiny surface mounted sense diodes. Over-voltage them, and they are gonzo.

I have repaired my SGC230 twice now. Those surface mount diodes are difficult to replace. A good magnifying lamp, temp controlled iron, and huge patience is needed. I think the circuit board may not survive a 3rd repair, so I am very careful now with the power I run. Each time I blew the sense circuit, I took out 3 or 4 diodes, so it was not an easy repair.

Kevin WM0F

--- In Smartuners@yahoogroups.com, Ron Skelton <w6wo@...> wrote:
>
> What a great response Steve , Thanks so much . I am also curious about
> the 80 W CW limit and what duty cycle this assumes
>
> andros2112 wrote:
> >
> >

No virus found in this incoming message.
Checked by AVG - www.avg.com Version: 8.5.426 / Virus Database: 270.14.100/2554 - Release Date: 12/09/09 07:32:00

I just pulled up the SG-230 manual from the SGCworld site and searched
for CW and 80 and could find no mention of a 80w limit. I admit to
briefly running mine pretty close to the 200w limit when setting up the
amplifier, but there is 100 feet of RG-213 before it hits the coupler
which assured me somewhat. Until now, that is. Think maybe I should wire
the dummy load in through a switch just in case.

Ken
M1SLH


kevin4617 wrote:
> Yes, that was a great response by Steve.
>
> On the 80W CW limit, I don't know what duty cycle is assumed, but what I do
know is that I have, not once, but twice, exceeded the 80W limit and blew out
the RF tuning sense diodes.  The first time, I thought it was lightning, or some
other random event.  The 2nd time, I got to thinking about what I did and
realized I was running well over 100w CW trying to get through to a dxpedition.
>
> I had not read the manual carefully enough, and did not know that CW was
limited to 80w.  The tuner is rated to handle 200w at SSB duty cycle, which is
what, maybe 30%?  So, that would imply on CW, better keep the power below 80W if
you a pounding out a lot of code.  It is not like you are burning up some device
that is designed to handle power, these are tiny surface mounted sense diodes. 
Over-voltage them, and they are gonzo.
>
> I have repaired my SGC230 twice now.  Those surface mount diodes are difficult
to replace.  A good magnifying lamp, temp controlled iron, and huge patience is
needed.  I think the circuit board may not survive a 3rd repair, so I am very
careful now with the power I run.  Each time I blew the sense circuit, I took
out 3 or 4 diodes, so it was not an easy repair.
>
>

Yes, that was a great response by Steve.

On the 80W CW limit, I don't know what duty cycle is assumed, but what I do know
is that I have, not once, but twice, exceeded the 80W limit and blew out the RF
tuning sense diodes.  The first time, I thought it was lightning, or some other
random event.  The 2nd time, I got to thinking about what I did and realized I
was running well over 100w CW trying to get through to a dxpedition.

I had not read the manual carefully enough, and did not know that CW was limited
to 80w.  The tuner is rated to handle 200w at SSB duty cycle, which is what,
maybe 30%?  So, that would imply on CW, better keep the power below 80W if you a
pounding out a lot of code.  It is not like you are burning up some device that
is designed to handle power, these are tiny surface mounted sense diodes. 
Over-voltage them, and they are gonzo.

I have repaired my SGC230 twice now.  Those surface mount diodes are difficult
to replace.  A good magnifying lamp, temp controlled iron, and huge patience is
needed.  I think the circuit board may not survive a 3rd repair, so I am very
careful now with the power I run.  Each time I blew the sense circuit, I took
out 3 or 4 diodes, so it was not an easy repair.

Kevin WM0F

--- In Smartuners@yahoogroups.com, Ron Skelton <w6wo@...> wrote:
>
> What a great response Steve , Thanks so much . I am also curious about
> the 80 W CW limit and what duty cycle this assumes
>
> andros2112 wrote:
> >
> >

 

The basic circuit used in latest version is largely the same as your tuner, but SGC has moved to a new microprocessor that internally incorporates the functions of the EPROM (where the software resides) and the EEPROM (where the tuning data is stored) and this greatly simplifies the digital side of the circuit. The new unit is also constructed with surface mount components, and can be a real problem for some technicians to work on.

>From a operational standpoint, they will probably give the same results - assuming it works correctly, and have the same degree of reliability, and largely suffer from the same types of failure. The new versions CPU is bloody expensive - About $75.00 + shipping. Since it has to be programmed by SGC, it is - for all practical purposes, a proprietary part. The older unit uses a CPU that is getting harder to find, but for the moment is still available from multiple sources. Its software resides in a dedicated EPROM. The old versions CPU is NOT a proprietary part.

For the moment, I'd say the older unit has an edge from a repairability standpoint.

Inspect the relays carefully - looking for burned contacts - especially on the units near the output shunt capacitors. Also check for corrosion on the "arms" that support the relay contacts.

To test the unit, start by moving jumper "J3" - "Tune from Memory" to "NO". Test the unit with the cover removed and make sure all relays change state (move)during the tuning process. Make sure you have a first rate ground - so that the test is fair, and a reasonable long antenna (30 feet or so).

The unit should find a match in a few seconds for any given frequency. Test all of the bands you intend to use. Return to previously tested bands. Test them in random order. The length of time for the tune process to complete should be pretty consistent.

Return "J3" to "YES", and re-test using the same process. In short order, the unit should learn the proper tuning match for a given frequency, and find a near instant match whenever you return to that frequency.

BTW - I repair marine electronic equipment, and have a lot of experience with these units. Feel free to email or call me at the shop if you need any help. 941.748.1941

73's Steve - KG4LJB

-- In Smartuners@yahoogroups.com, Ron Skelton <w6wo@...> wrote:
>
> I have the opportunity to buy one of these tuners
> *SN is 65833004.vintage around 1996/7 *
> *
> What changes (if any) have been made to the product since then ?*
>

No virus found in this incoming message.
Checked by AVG - www.avg.com Version: 8.5.426 / Virus Database: 270.14.98/2551 - Release Date: 12/07/09 19:34:00

 

Hi Ron,

That might be a question for the folks at the factory.

SGC contact page is here...

http://www.sgcworld.com/contactuscompanyPage.html

Sincerely,

David H. Hatch - N9ZRT

dave@olsc-gb.org

On Dec 6, 2009, at 2:44 PM, Ron Skelton wrote:

 

I have the opportunity to buy one of these tuners
SN is 65833004.vintage around 1996/7

What changes (if any) have been made to the product since then ?

No virus found in this incoming message.
Checked by AVG - www.avg.com Version: 8.5.426 / Virus Database: 270.14.98/2551 - Release Date: 12/07/09 19:34:00

The basic circuit used in latest version is largely the same as your tuner, but
SGC has moved to a new microprocessor that internally incorporates the functions
of the EPROM (where the software resides) and the EEPROM (where the tuning data
is stored) and this greatly simplifies the digital side of the circuit. The new
unit is also constructed with surface mount components, and can be a real
problem for some technicians to work on.

From a operational standpoint, they will probably give the same results -
assuming it works correctly, and have the same degree of reliability, and
largely suffer from the same types of failure. The new versions CPU is bloody
expensive - About $75.00 + shipping. Since it has to be programmed by SGC, it is
- for all practical purposes, a proprietary part. The older unit uses a CPU that
is getting harder to find, but for the moment is still available from multiple
sources. Its software resides in a dedicated EPROM. The old versions CPU is NOT
a proprietary part.

For the moment, I'd say the older unit has an edge from a repairability
standpoint.

Inspect the relays carefully - looking for burned contacts - especially on the
units near the output shunt capacitors. Also check for corrosion on the "arms"
that support the relay contacts.

To test the unit, start by moving jumper "J3" - "Tune from Memory" to "NO". Test
the unit with the cover removed and make sure all relays change state
(move)during the tuning process. Make sure you have a first rate ground - so
that the test is fair, and a reasonable long antenna (30 feet or so).

The unit should find a match in a few seconds for any given frequency. Test all
of the bands you intend to use. Return to previously tested bands. Test them in
random order. The length of time for the tune process to complete should be
pretty consistent.

Return "J3" to "YES", and re-test using the same process. In short order, the
unit should learn the proper tuning match for a given frequency, and find a near
instant match whenever you return to that frequency.

BTW - I repair marine electronic equipment, and have a lot of experience with
these units. Feel free to email or call me at the shop if you need any help.
941.748.1941

73's Steve - KG4LJB




-- In Smartuners@yahoogroups.com, Ron Skelton <w6wo@...> wrote:
>
> I have the opportunity to buy one of these tuners
> *SN is 65833004.vintage around 1996/7 *
> *
> What changes (if any) have been made to the product since then ?*
>

I havea SmartLock Pro controller box with manual and schematic.
Unfortunately the cable was cut to disconnect it from the 230.
Would anyone like to make an offer before I list it on Ebay? Craig

I want to thanks the hams who responded to my question regarding the use of a
feedline choke.  I plans to install two:  one at the station end and one just
ahead of my SG-237.  What I really need is about 25 more radials!

73 de K6SBA
David in Santa Barbara CA

It well advised, if this is a station installation, to properly ground the
coax.

1.  where it enters a tower or pole (ground to pole or tower).
2.  where it exits a tower or pole (ground to pole or tower).
Note:  make sure the tower or pole is properly grounded...duh!!
3. directly prior to entering a building as close to earth as possible
4. at the equipment within the building.

Do this and more often than not, the chokes are not needed.
Also, after grounding, it's well advised to actually measure (as opposed to
guessing) to determine
if there are any common mode currents on your coax.
If the coax runs along the ground for some length, this also helps reduce RF
common mode currents but can create safety concerns.

Note:  If you live near a strong broadcast station/s, common mode currents
can be very difficult to measure.

You'd be amazed to see common mode currents (created in poor installations)
disappear when good grounding techniques are employed!

Cheers!

Jim, K7WFR




----- Original Message -----
From: "Randy Farmer" <w8fn@...>
To: <Smartuners@yahoogroups.com>
Sent: Sunday, November 29, 2009 7:43 PM
Subject: Re: [Smartuners] Feedline "Chokes": Yes or No?


>
> Best practice is to use a choke at both the antenna feed end AND the radio
> end. That way it blocks any common-mode RF currents that may be induced
> anywhere along the feedline and keeps RF from getting into either the
> tuner control logic or the station equipment. For long feedlines it can
> even be a good idea to put one around halfway in between the ends to break
> up any re-radiation effects that could arise from currents on the outer
> coax conductor.
>
> 73...
> Randy, W8FN
>
>
>
>  I would say yes use a choke.   If the feed line is run paralel to the
> radials you might want to use a choke some distance from the tuner
> (perhaps where it enters the shack ?)
>
>  I found adding a choke to the feed line for my SGC237 reduced RFI issues.
>
>  Regards
>  Mark VE7AFZ
>
>
>  From: K6SBA <ingerassociates@...>
>  To: Smartuners@yahoogroups.com
>  Sent: Sun, November 29, 2009 9:01:34 AM
>  Subject: [Smartuners] Feedline "Chokes": Yes or No?
>
>
>
>  In the past I have included a feedline isolation choke at the base of my
> verticals. This has consisted of about 25 feet of RG-213 close wound on a
> section of 4" ABS pipe. I am about install an SG-237 at the base of my
> homebrew 43 ft. vertical. I am interested in peoples' experience (or even
> opinions) about using a choke in conjunction with the autotuner. The
> configuration would be feedline>choke> autotuner> antenna.
>
>  Thanks in advance.
>
>  73 de K6SBA
>  David in Santa Barbara CA
>
>

I would say yes use a choke.   If the feed line is run paralel to the radials you might want to use a choke some distance from the tuner (perhaps where it enters the shack ?)
 
I found adding a choke to the feed line for my SGC237 reduced RFI issues.  
 
Regards
Mark VE7AFZ


From: K6SBA <ingerassociates@...>
To: Smartuners@yahoogroups.com
Sent: Sun, November 29, 2009 9:01:34 AM
Subject: [Smartuners] Feedline "Chokes": Yes or No?

 

In the past I have included a feedline isolation choke at the base of my verticals. This has consisted of about 25 feet of RG-213 close wound on a section of 4" ABS pipe. I am about install an SG-237 at the base of my homebrew 43 ft. vertical. I am interested in peoples' experience (or even opinions) about using a choke in conjunction with the autotuner. The configuration would be feedline>choke> autotuner> antenna.

Thanks in advance.

73 de K6SBA
David in Santa Barbara CA

In the past I have included a feedline isolation choke at the base of my
verticals. This has consisted of about 25 feet of RG-213 close wound on a
section of 4" ABS pipe.  I am about install an SG-237 at the base of my homebrew
43 ft. vertical.  I am interested in peoples' experience (or even opinions)
about using a choke in conjunction with the autotuner.  The configuration would
be feedline>choke>autotuner>antenna.

Thanks in advance.

73 de K6SBA
David in Santa Barbara CA

I just bought an SG-230, and hooked up the power.  It seems to work fine.  I
need a box for the status lights, power, tuning etc.  Anyone know where such a
box can be purchased?  Thanks in advance for any help.

+++

IF YOU CAN READ THIS, THANK A TEACHER.  IF YOU CAN READ THIS, IN ENGLISH, THANK
A SOLDIER.

+++


     Talley

Thanks, Tim!  I appreciate the information. Now I now what size of ring terminal
to put on the radiating element and the counterpoise.

73s de W1YB

Johnne Lee

--- In Smartuners@yahoogroups.com, "Tim Armagost" <tim@...> wrote:
>
> Looks like the antenna (radiating element) is a 10-32 bolt and the ground is
1/4-20 bolt...
>
> HTH!
>
> Tim, WBØTUB
>
>   ----- Original Message -----
>   From: JohnneA
>   To: Smartuners@yahoogroups.com
>   Sent: Friday, November 27, 2009 10:24 AM
>   Subject: [Smartuners] Autotuner connector specs question
>
>
>
>   Hi All,
>
>   I have cut my wire and coax in preparation for deployment of the antenna
system. I do not have an auto-coupler as yet so I need for some kind soul to
measure their auto-couplers' connectors for both the ground and the radiating
element. I want to install the connectors on both the antenna and the
counterpoise so that I will be completely prepared when I purchase an
auto-coupler.
>
>   I have yet to decide whether I will purchase an SGC-237 or a CG-3000 (or
maybe an AH-4.)
>
>   I understand that extensions for the control cable are readily available.
>
>   Thanks in advance.
>
>   73s de W1YB
>

I use an inverted L 145' long and a counterpoise (strung out on the ground )
155'long with my AH4 that is quite similar to the SG230.

Any of these lengths should work for you with a single counterpoise 5%
longer.

27' (23-32)
40' (35-44)
58' (52-64)
76' (70-81)
95' (92-98)
109' (105-113)
145' (140-148)

73,
Bert W1DFU


----- Original Message -----
From: "idmottishaw" <idmottishaw@...>
To: <Smartuners@yahoogroups.com>
Sent: Friday, November 27, 2009 2:08 PM
Subject: [Smartuners] Re: Counterpoise length SG230


Thanks for info Callum, my question is not worded that well.
I was thinking of a inverted L with say 50ft top but being a small garden
perhaps a couple of counterpoise / radials about 20-30ft long.
Working HF from your boat sound great.

Regards
Ian

--- In Smartuners@yahoogroups.com, Callum MØMCX <callum@...> wrote:
>
> The mention of a "counterpoise" means they are referring to a vertical
> antenna arrangement. I once used my boat as the radiating element and a
> 12m
> vertical as the ground. It's quite amusing that I worked some interesting
> DX
> on 20m like this - but making the "counterpoise" too short and you can get
> little RF burns off the mic and stuff. It basically won't work correctly.
> Some people have also experienced RF on their audio, control lines and all
> sorts because of the difficulty in the earth working incorrectly.
>
>
>
> Now. if you are making a doublet then indeed, both sides will be the same
> length and in this way it works great.
>
>
>
> Did I read your question right?
>
>
>
> Callum McCormick
>
> t: 07976 631881
>
>  <http://www.m0mcx.co.uk/> http://www.m0mcx.co.uk/
>
>
>
>
>
> From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com] On
> Behalf Of idmottishaw
> Sent: 26 November 2009 21:09
> To: Smartuners@yahoogroups.com
> Subject: [Smartuners] Counterpoise length SG230
>
>
>
>
>
> Hi All,
>
> In the instructions for the SG230 it states that the counterpoise 'must'
> be
> longer than the radiating element.Is this really the case?
>

My feed line got chewed up in the hinge of a car seat a while back.

Does anyone have a pic of what the connections inside look like for
replacing the feed line?

It's a pain for me to disassemble the housing just to see first as it
is mounted in my vehicle.

--
73      de     Chris       KC2RGW
-----------------------------------------------
˙dn ǝpıs ʇɥƃıɹ ɹoʇıuoɯ ɹnoʎ uɹnʇ
ǝsɐǝןd 'sıɥʇ ƃuıpɐǝɹ ǝɹɐ noʎ ɟı

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

From: JohnneA

To: Smartuners@yahoogroups.com

Sent: Friday, November 27, 2009 10:24 AM

Subject: [Smartuners] Autotuner connector specs question

 

Hi All,

I have cut my wire and coax in preparation for deployment of the antenna system. I do not have an auto-coupler as yet so I need for some kind soul to measure their auto-couplers' connectors for both the ground and the radiating element. I want to install the connectors on both the antenna and the counterpoise so that I will be completely prepared when I purchase an auto-coupler.

I have yet to decide whether I will purchase an SGC-237 or a CG-3000 (or maybe an AH-4.)

I understand that extensions for the control cable are readily available.

Thanks in advance.

73s de W1YB

Thanks for info Callum, my question is not worded that well.
I was thinking of a inverted L with say 50ft top but being a small garden
perhaps a couple of counterpoise / radials about 20-30ft long.
Working HF from your boat sound great.

Regards
Ian

--- In Smartuners@yahoogroups.com, Callum MØMCX <callum@...> wrote:
>
> The mention of a "counterpoise" means they are referring to a vertical
> antenna arrangement. I once used my boat as the radiating element and a 12m
> vertical as the ground. It's quite amusing that I worked some interesting DX
> on 20m like this – but making the "counterpoise" too short and you can get
> little RF burns off the mic and stuff. It basically won't work correctly.
> Some people have also experienced RF on their audio, control lines and all
> sorts because of the difficulty in the earth working incorrectly.
>
>
>
> Now. if you are making a doublet then indeed, both sides will be the same
> length and in this way it works great.
>
>
>
> Did I read your question right?
>
>
>
> Callum McCormick
>
> t: 07976 631881
>
>  <http://www.m0mcx.co.uk/> http://www.m0mcx.co.uk/
>
>
>
>
>
> From: Smartuners@yahoogroups.com [mailto:Smartuners@yahoogroups.com] On
> Behalf Of idmottishaw
> Sent: 26 November 2009 21:09
> To: Smartuners@yahoogroups.com
> Subject: [Smartuners] Counterpoise length SG230
>
>
>
>
>
> Hi All,
>
> In the instructions for the SG230 it states that the counterpoise 'must' be
> longer than the radiating element.Is this really the case?
> What if you have two or three shorter elements instead or a Half wave
> radiator which for say 80m only normally needs a short counterpoise (1-2
> metres)?
> If you make a doublet with balanced feeder to the smart tuner with the
> counterpoise side longer, then it is no longer balanced or a doublet?
>
> I'm a bit confused :-)
>
> 73 Ian
>

Hi All,

I have cut my wire and coax in preparation for deployment of the antenna system.
I do not have an auto-coupler as yet so I need for some kind soul to measure
their auto-couplers' connectors for both the ground and the radiating element. I
want to install the connectors on both the antenna and the counterpoise so that
I will be completely prepared when I purchase an auto-coupler.

I have yet to decide whether I will purchase an SGC-237 or a CG-3000 (or maybe
an AH-4.)

I understand that extensions for the control cable are readily available.

Thanks in advance.

73s de W1YB

Hi All,

In the instructions for the SG230 it states that the counterpoise 'must' be
longer than the radiating element.Is this really the case?
What if you have two or three shorter elements instead or a Half wave radiator
which for say 80m only normally needs a short counterpoise (1-2 metres)?
If you make a doublet with balanced feeder to the smart tuner with the
counterpoise side longer, then it is no longer balanced or a doublet?

I'm a bit confused :-)

73 Ian