Having never wound a balun before, pardon if this is an elementary
question, but...

I recently got a Murch 2000B antenna tuner off eBay. It's a commercial
version of the so-called ultimate transmatch. A T-network design.

For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

Thanks for any info.

Bob
k5qwg

Bob Miller wrote:
For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

It's probably a 4:1 voltage balun which does exhibit
a DC short. That's actually good for cutting down on
static electricity.
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

On Sat, 04 Jun 2005 14:58:33 -0500, Cecil Moore
wrote:

Bob Miller wrote:
For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

It's probably a 4:1 voltage balun which does exhibit
a DC short. That's actually good for cutting down on
static electricity.

Thanks, Cecil, I noticed a more up-to-date MFJ tuner doesn't show
continuity across the balanced line terminals; just wanted to make
sure the Murch balun wasn't whacked out.

Bob
k5qwg

On Sat, 04 Jun 2005 14:58:33 -0500, Cecil Moore
wrote:

Bob Miller wrote:
For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

It's probably a 4:1 voltage balun which does exhibit
a DC short. That's actually good for cutting down on
static electricity.

Okay, Cecil, Dave, one more elementary question. My copy of the
instructions for the Murch 2000B says the following:

"Connect balanced line to connection marked Balance Line with Jumper
as indicated on back panel."

On the back panel, there's a painted line between the two balanced
line connections. Surely, they don't mean to run a jumper wire between
the two connections *while* a balanced line is attached?

It seems to tune fine without the jumper -- I'm afraid I'd blow
something up with the jumper.

Bob
k5qwg

In article ,
Bob Miller wrote:

It's probably a 4:1 voltage balun which does exhibit
a DC short. That's actually good for cutting down on
static electricity.

Okay, Cecil, Dave, one more elementary question. My copy of the
instructions for the Murch 2000B says the following:

"Connect balanced line to connection marked Balance Line with Jumper
as indicated on back panel."

On the back panel, there's a painted line between the two balanced
line connections. Surely, they don't mean to run a jumper wire between
the two connections *while* a balanced line is attached?

No, I think the painted line is meant to indicate "the line is
connected to/between these two points." The "jumper" they refer to
probably refers to a short section of balanced line, to be connected
between the transmatch and whatever terminals you use to terminate the
ladder-line or open-wire line when it comes into your shack.

It seems to tune fine without the jumper -- I'm afraid I'd blow
something up with the jumper.

Yeah, you'd be trying to tune a near-short-circuit... often difficult
and the results are less than productive :-)

There are some transmatches in which the balun is normally out of
circuit, and has to be jumpered to the hot side of the unbalanced
output when you want to use it. That *might* be what they're
referring to?

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Bob Miller wrote:
Okay, Cecil, Dave, one more elementary question. My copy of the
instructions for the Murch 2000B says the following:

"Connect balanced line to connection marked Balance Line with Jumper
as indicated on back panel."

On the back panel, there's a painted line between the two balanced
line connections. Surely, they don't mean to run a jumper wire between
the two connections *while* a balanced line is attached?

It seems to tune fine without the jumper -- I'm afraid I'd blow
something up with the jumper.

If it's like my MFJ-949E, the balun is completely out of the
circuit until the jumper is installed. Without the jumper on
the MFJ, there would be no output at the balanced line
output terminals. Do you have a schematic?
--
73, Cecil http://www.qsl.net/w5dxp


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

On Sat, 04 Jun 2005 19:24:15 -0500, Cecil Moore
wrote:

Bob Miller wrote:
Okay, Cecil, Dave, one more elementary question. My copy of the
instructions for the Murch 2000B says the following:

"Connect balanced line to connection marked Balance Line with Jumper
as indicated on back panel."

On the back panel, there's a painted line between the two balanced
line connections. Surely, they don't mean to run a jumper wire between
the two connections *while* a balanced line is attached?

It seems to tune fine without the jumper -- I'm afraid I'd blow
something up with the jumper.

If it's like my MFJ-949E, the balun is completely out of the
circuit until the jumper is installed. Without the jumper on
the MFJ, there would be no output at the balanced line
output terminals. Do you have a schematic?

Sorry, I don't have a schematic.

On my MFJ 989c, I have two balanced line connectors. I also have a 3rd
connector for Random Wire, and a 4th odd connector. For balanced line
operation, I install a jumper between the Random Wire and 4th
connectors.

On the Murch 2000B, there are two connectors for balanced line. And a
3rd connector for Random Wire. The directions seem to be saying put a
jumper on the balanced line connectors for balanced line operation.

"Connect any antenna with single wire feed to connection marked Random
Wire. Connect balanced line to connection marked Balanced Line with
Jumper as indicated on back panel." (and there's a painted line
between the Balanced Line connectors.)

If it's helpful, there are pictures, inside & out, of the Murch tuner
at
http://cgi.ebay.com/ws/eBayISAPI.dll...m=5757714 402


Bob
k5qwg

Bob Miller wrote:
"Connect any antenna with single wire feed to connection marked Random
Wire. Connect balanced line to connection marked Balanced Line with
Jumper as indicated on back panel." (and there's a painted line
between the Balanced Line connectors.)

If it's helpful, there are pictures, inside & out, of the Murch tuner at
http://cgi.ebay.com/ws/eBayISAPI.dll...m=5757714 402

I suspect the jumper wire needs to go between the random wire
terminal and one of the balanced line terminals. That's the
way it is on my MFJ. On the inside, do the balanced line
terminals go anywhere besides the balun?
--
73, Cecil http://www.qsl.net/w5dxp

----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

In article ,
Bob Miller wrote:

For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

Very probably normal... or, at least, to be expected of many types
of balun and thus not diagnostic of a failure. You're probably
reading the DC resistance one or more of the windings, which would be
rather less than an ohm.

Based on what I see in Sevick's book on baluns and ununs, both the
Guanella 4:1 current balun and the various Ruthroff voltage balun
configurations would exhibit this behavior. A Guanella 1:1 with the
center of the load un-grounded would not, nor would a Reisert or W2DU
1:1 balun.

Now, for something completely different. If you want to revisit an
old controversy, and if you're not adverse to modifying a classic
piece of equipment, you might want to review the various debates about
the pros and cons of the Ultimate Transmatch vs. the SPC
configuration. See if you can locate a copy of the August 1981 QST,
and review the Technical Correspondence column on pages 42-43.

As I understand it, the SPC configuration can be shown to have some
significant technical advantages over the Ultimate Transmatch, in terms
of matching range and harmonic attenuation, when the same component
values are used in each. It is reportedly possible to re-wire an
Ultimate into an SPC configuration little or no cost, as both use a
split-stator capacitor (just in different places in the circuit).

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Sat, 04 Jun 2005 20:11:38 -0000, (Dave Platt)
wrote:

In article ,
Bob Miller wrote:

For balanced line, it has a "broadband toroidal transformer" according
to the review in a 1980 QST. When I place a VOM multi-meter across the
two balanced line terminals, it shows continuity. Is that normal, or
is the balun cooked or shorted?

Very probably normal... or, at least, to be expected of many types
of balun and thus not diagnostic of a failure. You're probably
reading the DC resistance one or more of the windings, which would be
rather less than an ohm.

Based on what I see in Sevick's book on baluns and ununs, both the
Guanella 4:1 current balun and the various Ruthroff voltage balun
configurations would exhibit this behavior.

I kinda suspected so, but wasn't sure.

A Guanella 1:1 with the
center of the load un-grounded would not, nor would a Reisert or W2DU
1:1 balun.

Now, for something completely different. If you want to revisit an
old controversy, and if you're not adverse to modifying a classic
piece of equipment, you might want to review the various debates about
the pros and cons of the Ultimate Transmatch vs. the SPC
configuration. See if you can locate a copy of the August 1981 QST,
and review the Technical Correspondence column on pages 42-43.

As I understand it, the SPC configuration can be shown to have some
significant technical advantages over the Ultimate Transmatch, in terms
of matching range and harmonic attenuation, when the same component
values are used in each. It is reportedly possible to re-wire an
Ultimate into an SPC configuration little or no cost, as both use a
split-stator capacitor (just in different places in the circuit).

Thanks, Dave, I have a 1985 arrl handbook that shows the differences
between the Ultimate Transmatch and the SPC circuit, and I also have
some modification instructions on the Murch unit itself, but I haven't
tried changing anything yet. Still playing with it, as it came.

Bob
k5qwg