Elecraft › [MM]

Boots for the XG3...

Classic

List

Threaded

14 messages Options

John Ragle

Boots for the XG3...

A few days back I inquired of the list if anyone knew of a small
post-amp that would prefilter the XG3 square wave and give it about 30
dB boost. There were no answers. The problem seems to be that most QRP
or QRPp amps already require a few tenths of a watt input, and the 1 mW
from the XG3 is just too tiny...

I have been specifically thinking about using the XG3 (in its spare
time) as a 6 meter beacon. Just hooking it up to a "resonant" antenna is
not (IMHO) legal, since antennas (think center-fed half wave doublets)
do not discriminate against ODD harmonics. FCC requires better...see
§97.307 Emission standards, section (e).

I have been thinking this over, and it looks like the best answer is to
build around a 20 dB gain block running in to a power module, such as
the MAR-6 gain block into a M57735 power module. The output from the XG3
would need to be low-passed before the gain block, since the usual gain
blocks are quite wide band (e.g. DC-3 GHz, etc.).

HOWEVER, a glance at the manual for the XV series transverters already
shows a transmit path designed and ready, in the schematic for the XV50.
Aside from ~dozen SMD caps in the filtering (not needed!) connecting the
mixer to the SGA7489 gain block, the needed component list is rather
short, about 26 parts, most of which are mundane. I asked Wayne if
Elecraft would bag up these parts and sell them to me as a partial kit,
and his response was more or less positive, but he requested that I poll
the list to see if there is any other interest:

-----> A partial kit, no enclosure or circuit board, to assemble a 6
meter post-amp for the XG3 that would produce 1-5 watts. <-----

Note: the SGA7489 gain block is obsolete but the device remains in the
supply chain.
Note: the RA30H0608M power module is designed to put out 30 watts in the
68-88 MHz range. To drive it to this power level from the XG3 might
require cascading two gain blocks. A substitute part is the M57735
mentioned above, designed for 25 watts at 50-54 MHz.

I think that a post amp built "ugly style" around these ideas would fit
into an Altoids tin. The only hitch is proper heat-sinking of the power
module. The layout used for the XV50 takes care of the biasing.

*****

So, I am asking the list: "Is there any interest out there amongst XG3
owners in having Elecraft bag up a partial kit as outlined above?"

*****

This note is also going directly to Eric at Elecraft, who holds the
reins for manufacturing...

John Ragle -- W1ZI

P.S. The schematics for the XV50 is included in my manuals for my XV144,
which BTW works wonderfully...

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Joe Subich, W4TV-4

Re: Boots for the XG3...

> So, I am asking the list: "Is there any interest out there amongst XG3
> owners in having Elecraft bag up a partial kit as outlined above?"

If such a kit was to be made available, I would suggest a gain block
capable of operation on the three highest bands (28-148 MHz) with the
necessary LPF values for each band.

I'm also not sure that a kit should be capable of much more than 1 W
output as a bunch of 20 W signals with fairly high levels of phase
noise would not be exactly welcome on most bands.

73,

... Joe, W4TV

On 6/25/2011 6:14 AM, John Ragle wrote:

> A few days back I inquired of the list if anyone knew of a small
> post-amp that would prefilter the XG3 square wave and give it about 30
> dB boost. There were no answers. The problem seems to be that most QRP
> or QRPp amps already require a few tenths of a watt input, and the 1 mW
> from the XG3 is just too tiny...
>
> I have been specifically thinking about using the XG3 (in its spare
> time) as a 6 meter beacon. Just hooking it up to a "resonant" antenna is
> not (IMHO) legal, since antennas (think center-fed half wave doublets)
> do not discriminate against ODD harmonics. FCC requires better...see
> §97.307 Emission standards, section (e).
>
> I have been thinking this over, and it looks like the best answer is to
> build around a 20 dB gain block running in to a power module, such as
> the MAR-6 gain block into a M57735 power module. The output from the XG3
> would need to be low-passed before the gain block, since the usual gain
> blocks are quite wide band (e.g. DC-3 GHz, etc.).
>
> HOWEVER, a glance at the manual for the XV series transverters already
> shows a transmit path designed and ready, in the schematic for the XV50.
> Aside from ~dozen SMD caps in the filtering (not needed!) connecting the
> mixer to the SGA7489 gain block, the needed component list is rather
> short, about 26 parts, most of which are mundane. I asked Wayne if
> Elecraft would bag up these parts and sell them to me as a partial kit,
> and his response was more or less positive, but he requested that I poll
> the list to see if there is any other interest:
>
> -----> A partial kit, no enclosure or circuit board, to assemble a 6
> meter post-amp for the XG3 that would produce 1-5 watts.<-----
>
> Note: the SGA7489 gain block is obsolete but the device remains in the
> supply chain.
> Note: the RA30H0608M power module is designed to put out 30 watts in the
> 68-88 MHz range. To drive it to this power level from the XG3 might
> require cascading two gain blocks. A substitute part is the M57735
> mentioned above, designed for 25 watts at 50-54 MHz.
>
> I think that a post amp built "ugly style" around these ideas would fit
> into an Altoids tin. The only hitch is proper heat-sinking of the power
> module. The layout used for the XV50 takes care of the biasing.
>
> *****
>
> So, I am asking the list: "Is there any interest out there amongst XG3
> owners in having Elecraft bag up a partial kit as outlined above?"
>
> *****
>
> This note is also going directly to Eric at Elecraft, who holds the
> reins for manufacturing...
>
> John Ragle -- W1ZI
>
> P.S. The schematics for the XV50 is included in my manuals for my XV144,
> which BTW works wonderfully...
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Rick Dettinger-3

Re: Boots for the XG3...

In reply to this post by John Ragle

Would the "Boots" need type acceptance if offered by Elecraft?
Does the 15 dB gain maximum rule apply?
Are QRP amplifier kits legal in any case?
Maybe Elecraft could offer a 1watt beacon kit based on the XG3. There
seems to be a lot of interest in QRP beacons.

73,

Rick Dettinger K7MW

On Jun 25, 2011, at 3:14 AM, John Ragle wrote:

> A few days back I inquired of the list if anyone knew of a small
> post-amp that would prefilter the XG3 square wave and give it about 30
> dB boost. There were no answers. The problem seems to be that most QRP
> or QRPp amps already require a few tenths of a watt input, and the 1
> mW
> from the XG3 is just too tiny...
>
> I have been specifically thinking about using the XG3 (in its spare
> time) as a 6 meter beacon. Just hooking it up to a "resonant"
> antenna is
> not (IMHO) legal, since antennas (think center-fed half wave doublets)
> do not discriminate against ODD harmonics. FCC requires better...see
> §97.307 Emission standards, section (e).
>
> I have been thinking this over, and it looks like the best answer is
> to
> build around a 20 dB gain block running in to a power module, such as
> the MAR-6 gain block into a M57735 power module. The output from the
> XG3
> would need to be low-passed before the gain block, since the usual
> gain
> blocks are quite wide band (e.g. DC-3 GHz, etc.).
>
> HOWEVER, a glance at the manual for the XV series transverters already
> shows a transmit path designed and ready, in the schematic for the
> XV50.
> Aside from ~dozen SMD caps in the filtering (not needed!) connecting
> the
> mixer to the SGA7489 gain block, the needed component list is rather
> short, about 26 parts, most of which are mundane. I asked Wayne if
> Elecraft would bag up these parts and sell them to me as a partial
> kit,
> and his response was more or less positive, but he requested that I
> poll
> the list to see if there is any other interest:
>
> -----> A partial kit, no enclosure or circuit board, to assemble a 6
> meter post-amp for the XG3 that would produce 1-5 watts. <-----
>
> Note: the SGA7489 gain block is obsolete but the device remains in the
> supply chain.
> Note: the RA30H0608M power module is designed to put out 30 watts in
> the
> 68-88 MHz range. To drive it to this power level from the XG3 might
> require cascading two gain blocks. A substitute part is the M57735
> mentioned above, designed for 25 watts at 50-54 MHz.
>
> I think that a post amp built "ugly style" around these ideas would
> fit
> into an Altoids tin. The only hitch is proper heat-sinking of the
> power
> module. The layout used for the XV50 takes care of the biasing.
>
> *****
>
> So, I am asking the list: "Is there any interest out there amongst XG3
> owners in having Elecraft bag up a partial kit as outlined above?"
>
> *****
>
> This note is also going directly to Eric at Elecraft, who holds the
> reins for manufacturing...
>
> John Ragle -- W1ZI
>
> P.S. The schematics for the XV50 is included in my manuals for my
> XV144,
> which BTW works wonderfully...
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

AC7AC

Re: Boots for the XG3...

CONTENTS DELETED

The author has deleted this message.

John Ragle

Re: Boots for the XG3...off reflector...

In reply to this post by Joe Subich, W4TV-4

Hi, Joe...

You're quite right. I did the ff experiment: connect the XG3 to the
K3 input, set the XG3 to 50.100 MHz, set the K3 to 50.250 MHz, turn on
the XG3 and measure the increase in background noise on the P3.

In my case, the noise floor for my K3 looking into a dummy load is
-148 dB. Looking into the XG3 OFF it is the same, -148 dB. Looking at
the XG3 ON and set at -33 dBm, the K3 set at 50.250 MHz, the noise level
is -112 dB...that's 36 dB. It's a noisy sucker, alright...

I had not appreciated just how noisy. Of course, these conditions
are not very representative of on-the-air actualities, but you're quite
correct.

My motivation in all this has been the commentary we've been seeing
on the reflector about running an XG3 wide open into a directional
antenna with no filtering (quite illegally, IMO), and I hadn't
considered the noise generation question at all. When I've used my XG3
on my K3, it has always been set at -107 dBm, and no change in the noise
floor is observed.

John Ragle -- W1ZI

=====

On 6/25/2011 1:55 PM, Joe Subich, W4TV wrote:
> I'm even concerned at 1W. The XG3 is spec'd for -105 dBc/Hz. I can
> see a noticeable increase in the noise floor of my K3 on 50 MHz when
> the XG3 is set to -33 dBm.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bruce Beford-2

Re: Boots for the XG3...off reflector...

Ever since the XG3 firmware was updated to include CW sending capability I
have raised concerns that it's use as a beacon or hidden transmitter in a
"fox hunt" would not be legal (in the US) on VHF and up. It simple lacks
sufficient harmonic filtering. The phase noise is another issue, that cannot
be resolved by filtering. Amplifying this device would just make it worse.

The XG3 is a great piece of test equipment- no doubt. But- it is not clean
enough to use as a transmitter.

Whew. now that I have that off my chest, does anyone want to discuss the
illegality of using "/B" as a beacon identifier?

Bruce, N1RX

> My motivation in all this has been the commentary we've been seeing
> on the reflector about running an XG3 wide open into a directional
> antenna with no filtering (quite illegally, IMO), and I hadn't
> considered the noise generation question at all. When I've used my XG3
> on my K3, it has always been set at -107 dBm, and no change in the noise
> floor is observed.

> John Ragle -- W1ZI

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

k6dgw

Re: Boots for the XG3...off reflector...

On 6/25/2011 7:56 PM, Bruce Beford wrote:
> Whew. now that I have that off my chest, does anyone want to discuss the
> illegality of using "/B" as a beacon identifier?
>
And /R for repeaters. All the R's belong to Russia.

Fred K6DGW
TDY Topaz Lake NV
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Augie "Gus" Hansen

Re: Boots for the XG3...off reflector...

On 6/25/2011 8:31 PM, FredJensen wrote:
>
> And /R for repeaters. All the R's belong to Russia.

The ambiguity is resolved by position of the appendage.

The /R for repeater is valid. For example, I could run a repeater
with the call KB0YH/R.

If I were to operate in Russia, my call could have the form
R*/KB0YH, where the * represents zero or more characters. The call
sign RA3/KB0YH would apply in Central Russia.

73,
Gus Hansen

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

AC7AC

Re: Boots for the XG3...off reflector...

In reply to this post by k6dgw

CONTENTS DELETED

The author has deleted this message.

Phil Kane-2

Re: Boots for the XG3...off reflector...

On 6/25/2011 8:16 PM, Ron D'Eau Claire wrote:

> Gentlemen, I'm convinced that Amateur Radio may have nearly as
> many such self-appointed lawyers as we did in the Army - [snip]
> nearly as many as

Everyone tries to be a lawyer. Even some law school graduates. :-)

-- 73 de K2ASP - Phil Kane
(A real lawyer)
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Bruce Beford-2

Re: Boots for the XG3...off reflector...

In reply to this post by John Ragle

Possibly true. However, as a de-facto self-policing Radio Service, and in
the spirit of Elmering, it can sometimes to be helpful to discuss
long-propagated misconceptions, misunderstandings and misapplications of the
rules we operate under.

This is true of both operational and engineering practices. For instance,
many experienced radio amateurs still believe that there is a lower FCC
standard for spurious emissions on HF QRP transmitters than for those above
5W. That changed back in 2003, and now all HF transmitters must be at -43
dBc or better. That's 20 times (13 dB) tighter than the old spec. There are
exemptions for transmitters produced earlier, but those "placed in service"
after 1/1/2003 must meet the new, tighter spec. (see Part 97.307)

This means for example, that an amateur home-brewing from an older schematic
must make sure the finished transmitter incorporates sufficient harmonic
filtering and suppression of other spurious signals to meet the new spec.

It's not so much being a self-appointed lawyer, as helping our fellow
amateurs with opinions and advice that hopefully lead to good operating and
engineering practices. I know that I have learned a lot from those who have
Elmered me. I am constantly learning from those amateurs around me who are
more versed in areas than I am, including many on this list. Perhaps, in
some small way we can each learn from and help each other to promote a
culture of high performance in the Amateur Radio Service, a hobby we all
love.

73,
Bruce, N1RX

> Gentlemen, I'm convinced that Amateur Radio may have nearly as many such
> self-appointed lawyers as we did in the Army

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

GARY-2

Re: Boots for the XG3...

In reply to this post by John Ragle

John,
I'd like to offer an alternative idea-
Back in the 1990's Q-bit Corporation made a variety of compact broadband
amps for applications such as this. Many will happily run with a 0 dBm input
and provide 0.5 - 1w or more out. There are usually several models available
on eBay. Specs can still be found on the internet for some models. While
many are listed for +15 or +24 Vdc input they'll often run fine on less but
their gain will be lower.
73,
Gary
N6LRV

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of John Ragle
Sent: Saturday, June 25, 2011 3:14 AM
To: elecraft; Eric Swartz - WA6HHQ, Elecraft
Subject: [Elecraft] Boots for the XG3...

A few days back I inquired of the list if anyone knew of a small
post-amp that would prefilter the XG3 square wave and give it about 30
dB boost. There were no answers. The problem seems to be that most QRP
or QRPp amps already require a few tenths of a watt input, and the 1 mW
from the XG3 is just too tiny...

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

Alan Bloom

Re: Boots for the XG3...

In reply to this post by Joe Subich, W4TV-4

The other problem with adding boots to the XG3 is key clicks. As I
understand it, there is no key shaping. Not a problem with a 1 mw
transmitter but it might be objectionable with 20 watts.

Alan N1AL

On Sat, 2011-06-25 at 10:00 -0400, Joe Subich, W4TV wrote:

> > So, I am asking the list: "Is there any interest out there amongst XG3
> > owners in having Elecraft bag up a partial kit as outlined above?"
>
> If such a kit was to be made available, I would suggest a gain block
> capable of operation on the three highest bands (28-148 MHz) with the
> necessary LPF values for each band.
>
> I'm also not sure that a kit should be capable of much more than 1 W
> output as a bunch of 20 W signals with fairly high levels of phase
> noise would not be exactly welcome on most bands.
>
> 73,
>
> ... Joe, W4TV

John Ragle

Re: Boots for the XG3...

Alan...

After consideration of a couple of points raised on and off the list, I
wrote to Elecraft (re; parts):

"Wayne (& Eric)...

I am now pretty much convinced that my idea of building up a
post-amplifier for the XG3 is a *very bad* idea. As several people
pointed out to me, the jitter in the output (phase noise in the
frequency domain) makes the XG3 a poor candidate to put on the air as a
beacon, particularly when amplified to the 1-5 watt level."

I also wrote to a couple of others:

"I'm beginning to be sorry I raised this whole matter...as Joe
Subich points out, the XG3 is a fearsome noise generator, and running it
into 30 dB of amplification would make a mess. If you have an XG3, hook
it up to your K3 and watch the noise level well off the set frequency on
your P3. For my equipment, the noise level 250 kHz off the the set
frequency goes up by 36 dB when the XG3 is set at -33 dBm, and off scale
on the 0 dBm setting. No need to feed that to an antenna...

"My comments on the gain blocks and the power module are still
cogent, however, and [would] simplify the process of carding up a
crystal oscillator. Such a project might [also] bring in more people to
PIC programming and usage..."

It looks to me like a DDS source might be worthwhile exploring. There is
a relevant kit sold by Midnight Design Solutions, e.g.:

http://midnightdesignsolutions.com/dds60/

John Ragle -- W1ZI

=====

On 6/26/2011 9:22 PM, Alan Bloom wrote:

> The other problem with adding boots to the XG3 is key clicks. As I
> understand it, there is no key shaping. Not a problem with a 1 mw
> transmitter but it might be objectionable with 20 watts.
>
> Alan N1AL
>
>
> On Sat, 2011-06-25 at 10:00 -0400, Joe Subich, W4TV wrote:
>>> So, I am asking the list: "Is there any interest out there amongst XG3
>> > owners in having Elecraft bag up a partial kit as outlined above?"
>>
>> If such a kit was to be made available, I would suggest a gain block
>> capable of operation on the three highest bands (28-148 MHz) with the
>> necessary LPF values for each band.
>>
>> I'm also not sure that a kit should be capable of much more than 1 W
>> output as a bunch of 20 W signals with fairly high levels of phase
>> noise would not be exactly welcome on most bands.
>>
>> 73,
>>
>> ... Joe, W4TV
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>
>