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Kevin - K4VD

Power Supplies

Hi... I have a KX3 and normally run it on batteries. I also have a
Flex-6500 that runs on a big RS-50.

Last night during the QRP Fox Hunt (only 1 pelt) I decided to shutdown the
Flex and give the KX3 a shot. I powered up the Flex on its internal
batteries and, while I had the headphones on, plugged the RS-50 into it.

I was surprised with what I heard. Not only a low freq hum (60 or 120 Hz,
can't tell) but also a hash sound. The affect was fairly dramatic. I never
noticed anything on the Flex because I never ran that on batteries.

Today I swapped the KX3 between an old RS-12 linear I had laying around, a
12 V 15 Ah LiFePO4 battery pack and the internal batteries.

Going from internal (9.9V) to LiFePO4 (13.0V) I could hear no difference
and see no difference on the S-meter. I tried with the antenna connected
and disconnected.

Going from internal to the RS-12 (13.5 V) i could hear an increase in noise
level, about +S1, almost like turning up the RF gain a tad. When the
antenna was removed I heard no difference between internal battery and
RS-12. The additional noise wasn't objectionable - just sounded like the
noise floor jumped up a bit. No hum, no hash (or hiss).

I'm not sure what to make of this. It is apparent my RS-50 is in need of
some attention. I've had hit-and-miss experiences with Astron over the
years and now seeking an alternative. I just want something to work and
work well. I'm not even sure the RS-12 is up to spec with the small
increase in noise. My expectation is no change in noise going between
battery and power supply. Is this unrealistic?

eham's reviews are kind of not very helpful. There's plenty of good and
plenty of bad said about most makes and models. I'm thinking maybe I want
to run 100% battery for both the Flex and KX3 and just recharge when not in
use but I'm not sure how realistic that is. I do know I don't want to just
settle for the additional noise.

Switchers don't seem to be an option. While it might sound quiet at the
moment I can always see/hear that noise snake crawling across the panoramic
display right towards my current QSO.

Has anyone done some A/B comparisons while listening? I'm curious what you
may have experienced.

Thanks,
Kev K4VD
(VD = Vacation Day)
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hhoyt

Re: Power Supplies

Hi Kevin,

It is very possible that what you are experiencing is noise induced by
common-mode currents from your antenna system. These currents take any
path connected to the chassis of the rig including ANY AC mains
connected power supply, regardless of whether it is a switcher or
linear. The 10~100 nF average input-to-output capacitance of AC
operated power supplies provides a low-impedance path from the DC output
to the AC mains at ham frequencies. We have done a LOT of testing of
this characteristic here at PAE in order to separate conducted RFI from
RFI caused by common-mode current. After identifying this as a problem
which is usually worse in portable antennas we took extreme pains to
reduce this I/O capacitance with the Kx33 and we were able to achieve
less than 100pF, making the Kx33 much less conducive to allowing
common-mode noise.

Elimination of common-mode currents has many benefits including cleaning
up the pickup and radiation pattern of the antenna, elimination of
receive noise, and reducing or eliminating RFI-induced events like alarm
system triggering (ask me about that one). When using a superhet
receiver, baseband AC mains hum is not detected as it can be with a
direct-conversion (DC) receiver. This problem plagued early DC
receivers like the Heathkit HW-7 which often buzzed like a bee when
operated from a linear 12V supply.Fortunately this current can be
greatly reduced by the use of common-mode choking on the antenna
feedline, DC power lead or both. As has been stated here innumerable
times, common-mode choking should be done on all antennas at the
feedpoint and optionally but beneficially at the shack end as well. An
excellent reference on this subject has been written by our own Jim
Brown K9YC and can be viewed at:

http://audiosystemsgroup.com/RFI-Ham.pdf

Cheers & 73,
Howard Hoyt - WA4PSC
www.proaudioeng.com
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Kevin - K4VD

Re: Power Supplies

Thanks Dick and Howard...

The RS-50 is pretty new - maybe 6 months old and is in daily use. It wasn't
until I had a rig I could easily run on batteries did I notice the noise.
The RS-12 is quite old, maybe 15 years? It had been in storage about 10
years until trying it out today. I think I need to dig into the RS-50 and
just make sure everything is soldered and connected well.

As for common mode currents in the antenna... would that only be an issue
during transmit? I have an OCF so I know it can be an issue on transmit.
The OCF has a 1:1 current BALUN in the center. Is that enough or do I need
to add some additional choking just below the BALUN? I have a couple of the
NI4L line isolators (http://www.ni4l.com/hf-choke-line-isolator-1-8-300-mhz/).
I could put one up there and see what it does. I also have plenty of
clip-ons laying around. I'll try them on the power lead from the supply to
the radio.

The reports above were with *receive only* (with and without an antenna
attached). On the RS-50 the hum I'm hearing is what I think I'd expect to
hear from a less-that-well filtered linear power supply. The hash/hiss
noise I hear sounds more like a switching power supply, which it is not. I
don't know what in the power supply could be generating that noise.

The RS-12 does not have either the hum or hiss that I can hear. It just
sounds like the noise floor bumped up a little. I'm thinking Dick is right
and it is just the receiver responding to the increased voltage though it
is only about .5 volts above the external battery pack I was using.

Is every power supply going to generate a little noise or should I expect
no difference moving from battery to power supply?

Kev
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Don Wilhelm

Re: Power Supplies

Kev,

Yes, common mode current can be a problem on receive as well as transmit.
Transmit will cause RF-in-the-shack which is more obvious because you
can be 'bitten' by RF. On receive, the common mode current will result
in added receive noise due to pickup of noise on the transmission line.

OCF antennas are notorious for common mode currents as are end feds. A
balanced antenna is usually easier to tame, but are not immune.

For effective common mode chokes (some call them baluns or in-line
isolators), review the papers of K9YC Jim Brown on the subject. He has
posted many times on this reflector - bottom line is that many baluns
and in-line isolators are not very effective, how much so depends on the
frequency and the core material used.

In addition, if your antenna feedline does not run perpendicular to the
antenna for at least 1/4 wavelength, it can pick up currents from the
radiator. Yes, transmit is more extreme, but it happens in receive as
well. Antennas and transmission lines are bi-lateral devices, so what
happens in transmit happens in reverse on receive. The transmit effects
are easier to measure because the signals are larger.

As for the power supply itself, heed the information provided by Howie
Hoyt in this thread - he has done extensive testing in his development
of the PAE Kx33 power supply.

73,
Don W3FPR

On 7/15/2016 5:01 PM, Kevin - K4VD wrote:

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Richard Fjeld-2

Re: Power Supplies

In reply to this post by Kevin - K4VD

Kevin,
As I mentioned, I think this will depend on the Voltage Regulation level
in the receiver.
The Elecraft gear operates down low in voltage pretty well. I have
experienced what
you describe with other gear I have owned, but I have not compared if a
difference is heard
when going from a lower battery voltage to a higher PS voltage with
Elecraft gear.

I understand your problem is mainly with the RS-50. If you don't have a
scope, you
could put your DVM on AC and see if any AC can be measured on the 13.8
DC output
terminals. Try with, and without, some load. It's not a good test, but
something to try.

BTW, my experience with talking to Astron has been very good. They will
help you.

Dick, n0ce

On 7/15/2016 4:01 PM, Kevin - K4VD wrote:

> Thanks Dick and Howard...
>
> The RS-50 is pretty new - maybe 6 months old and is in daily use. It wasn't
> until I had a rig I could easily run on batteries did I notice the noise.
> The RS-12 is quite old, maybe 15 years? It had been in storage about 10
> years until trying it out today. I think I need to dig into the RS-50 and
> just make sure everything is soldered and connected well.
>
> As for common mode currents in the antenna... would that only be an issue
> during transmit? I have an OCF so I know it can be an issue on transmit.
> The OCF has a 1:1 current BALUN in the center. Is that enough or do I need
> to add some additional choking just below the BALUN? I have a couple of the
> NI4L line isolators (http://www.ni4l.com/hf-choke-line-isolator-1-8-300-mhz/).
> I could put one up there and see what it does. I also have plenty of
> clip-ons laying around. I'll try them on the power lead from the supply to
> the radio.
>
> The reports above were with *receive only* (with and without an antenna
> attached). On the RS-50 the hum I'm hearing is what I think I'd expect to
> hear from a less-that-well filtered linear power supply. The hash/hiss
> noise I hear sounds more like a switching power supply, which it is not. I
> don't know what in the power supply could be generating that noise.
>
> The RS-12 does not have either the hum or hiss that I can hear. It just
> sounds like the noise floor bumped up a little. I'm thinking Dick is right
> and it is just the receiver responding to the increased voltage though it
> is only about .5 volts above the external battery pack I was using.
>
> Is every power supply going to generate a little noise or should I expect
> no difference moving from battery to power supply?
>
> Kev
>

Vic Rosenthal

Re: Power Supplies

In reply to this post by Kevin - K4VD

You can tell if the noise floor increase is due to increased gain by seeing if signals increase in strength along with the noise.

As Don said, OCFs are prone to common mode issues. Perhaps the power supply is acting as a ground return for the 'common mode antenna'? A common mode choke on the power leads as you suggest might be worth a try.

Regarding clip-ons, remember that at HF you need multiple turns to have a noticeable affect. Also make sure they are the correct types of ferrite. The K9YC paper deals with that.

Vic 4X6GP

> On 16 Jul 2016, at 00:01, Kevin - K4VD <[hidden email]> wrote:
>
> Thanks Dick and Howard...
>
> The RS-50 is pretty new - maybe 6 months old and is in daily use. It wasn't
> until I had a rig I could easily run on batteries did I notice the noise.
> The RS-12 is quite old, maybe 15 years? It had been in storage about 10
> years until trying it out today. I think I need to dig into the RS-50 and
> just make sure everything is soldered and connected well.
>
> As for common mode currents in the antenna... would that only be an issue
> during transmit? I have an OCF so I know it can be an issue on transmit.
> The OCF has a 1:1 current BALUN in the center. Is that enough or do I need
> to add some additional choking just below the BALUN? I have a couple of the
> NI4L line isolators (http://www.ni4l.com/hf-choke-line-isolator-1-8-300-mhz/).
> I could put one up there and see what it does. I also have plenty of
> clip-ons laying around. I'll try them on the power lead from the supply to
> the radio.
>
> The reports above were with *receive only* (with and without an antenna
> attached). On the RS-50 the hum I'm hearing is what I think I'd expect to
> hear from a less-that-well filtered linear power supply. The hash/hiss
> noise I hear sounds more like a switching power supply, which it is not. I
> don't know what in the power supply could be generating that noise.
>
> The RS-12 does not have either the hum or hiss that I can hear. It just
> sounds like the noise floor bumped up a little. I'm thinking Dick is right
> and it is just the receiver responding to the increased voltage though it
> is only about .5 volts above the external battery pack I was using.
>
> Is every power supply going to generate a little noise or should I expect
> no difference moving from battery to power supply?
>
> Kev

hhoyt

Re: Power Supplies

In reply to this post by Kevin - K4VD

Hi Kevin,

>>As for common mode currents in the antenna... would that
>>only be an issue during transmit?

Except for very special cases, antenna systems display reciprocity, and
show very similar or identical current distributions at the frequency of
interest in transmit and receive, although the magnitudes are obviously
very different. In a well-balanced antenna system the currents in the
feedline are equal and of opposite phase, and in the case of a coax
feedine the resulting fields are contained within the coax, i.e. there
will be no current flowing on the outside of the coax shield. Antenna
system imbalances at the feedpoint will cause the imbalance current to
flow on the outside of the coax shield and radiate in transmit and
affect the antenna pattern. In receive the exact same imbalance will
exist and affect the pattern identically.

In both transmit and receive, these common-mode currents will be
conducted to the chassis of the rig and anything attached to it. They
also capacitively couple through the power supply, you, and anything
else touching or near the rig. When these currents couple through the
power supply to the AC line they effectively make the AC power system
part of the antenna and couple any noise present in the AC mains to the
receiver. As the antenna currents pass through the supply they can also
be modulated by the input-output impedance of the supply which varies at
the rate of rectification, so the supply can add its own noise to these
currents. Interestingly enough many people report stronger reception of
the desired signals along with the increased noise, certainly proving
the common-mode currents become part of the antenna system. Breaking
this current path with a common-mode choke will greatly reduce or
effectively eliminate this current and noise. For HF chokes we agree
with Jim Brown's recommendations and we supply mix 31 cores for the
purpose. Proper grounding at the rig can also reduce the AC mains coupling.

After selling thousands of these Kx33 supplies we have learned a lot
about the nature of most "power supply" RFI. We have found very few
instances where any supply was causing RFI by transverse conduction (RF
riding on the DC output) or radiation (proximity of the supply to the
receive antenna). In the almost all cases, antenna system imbalances
and the resulting common-mode currents were inducing RFI in the manner
described above. I'd be glad to send you a ferrite core to try, contact
me off-line.

I hope this helps,

Howard Hoyt - WA4PSC
www,proaudioeng.com
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Kevin - K4VD

Re: Power Supplies

Hi Howard and thanks for your explanations and patience. I need to do some
more testing a little later on with the KX3 on the RS-50. If I remember
right, I could hear the hum and hiss from the RS-50 only when the antenna
was attached. I think that goes along with what you are saying and I just
need to wrap my mind around that. I am prepared to deal with RF issues
while transmitting but not so prepared to think the problem could show up
during receive also.

So far I've added the NI4L HF Choke/Line Isolator just under the BALUN at
the feedpoint and another just at the rig. I've also added a few snap-ons
to the DC cord between the RS-50 and the radio at the RS-50 side. I want to
add more as soon as I can find the rest of them or possibly replace them
with the 2.4" ferrites at your site.

After doing the above I've noticed my tuning points have shifted a bit. I
need to get the analyzer on it to see by how much. I also *maybe* noticed a
reduction in noise on the Flex but to tell you the truth, I never really
noticed it on the Flex, only the KX3 made it obvious being able to switch
from battery to external power supply.

I need to do a little more testing if I can find the time this weekend. I
see the 2.4" ferrite core on your website and will probably place an order
for a couple/few. Does something like this go on each end of a line or do I
pick an end?

Thanks again,
Kevin

On Sat, Jul 16, 2016 at 7:19 AM, Howard Hoyt <[hidden email]> wrote:

> Hi Kevin,
>
> As for common mode currents in the antenna... would that
>>> only be an issue during transmit?
>>>
>>
> Except for very special cases, antenna systems display reciprocity, and
> show very similar or identical current distributions at the frequency of
> interest in transmit and receive, although the magnitudes are obviously
> very different. In a well-balanced antenna system the currents in the
> feedline are equal and of opposite phase, and in the case of a coax feedine
> the resulting fields are contained within the coax, i.e. there will be no
> current flowing on the outside of the coax shield. Antenna system
> imbalances at the feedpoint will cause the imbalance current to flow on the
> outside of the coax shield and radiate in transmit and affect the antenna
> pattern. In receive the exact same imbalance will exist and affect the
> pattern identically.
>
> In both transmit and receive, these common-mode currents will be conducted
> to the chassis of the rig and anything attached to it. They also
> capacitively couple through the power supply, you, and anything else
> touching or near the rig. When these currents couple through the power
> supply to the AC line they effectively make the AC power system part of the
> antenna and couple any noise present in the AC mains to the receiver. As
> the antenna currents pass through the supply they can also be modulated by
> the input-output impedance of the supply which varies at the rate of
> rectification, so the supply can add its own noise to these currents.
> Interestingly enough many people report stronger reception of the desired
> signals along with the increased noise, certainly proving the common-mode
> currents become part of the antenna system. Breaking this current path
> with a common-mode choke will greatly reduce or effectively eliminate this
> current and noise. For HF chokes we agree with Jim Brown's recommendations
> and we supply mix 31 cores for the purpose. Proper grounding at the rig
> can also reduce the AC mains coupling.
>
> After selling thousands of these Kx33 supplies we have learned a lot about
> the nature of most "power supply" RFI. We have found very few instances
> where any supply was causing RFI by transverse conduction (RF riding on the
> DC output) or radiation (proximity of the supply to the receive antenna).
> In the almost all cases, antenna system imbalances and the resulting
> common-mode currents were inducing RFI in the manner described above. I'd
> be glad to send you a ferrite core to try, contact me off-line.
>
> I hope this helps,
>
> Howard Hoyt - WA4PSC
> www,proaudioeng.com
>

Drew AF2Z

Re: Power Supplies

In reply to this post by Vic Rosenthal

Won't hurt to use a twisted pair cable between the PS and the rig. If
you have the standard DC power cable zip cord just unplug it, twist it
up real good, then plug it back in.

73,
Drew
AF2Z

On 07/16/16 00:12, Vic Rosenthal wrote:
> You can tell if the noise floor increase is due to increased gain by seeing if signals increase in strength along with the noise.
>
> As Don said, OCFs are prone to common mode issues. Perhaps the power supply is acting as a ground return for the 'common mode antenna'? A common mode choke on the power leads as you suggest might be worth a try.
>
> Regarding clip-ons, remember that at HF you need multiple turns to have a noticeable affect. Also make sure they are the correct types of ferrite. The K9YC paper deals with that.
>
> Vic 4X6GP
>
>

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Drew AF2Z

Re: Power Supplies

In reply to this post by Kevin - K4VD

I have an endfed wire antenna for the low bands so there is RF in the
shack which needs to be managed. In such a case a field strength meter
is handy in figuring out how to arrange equipment, cables, keyboards,
etc and placing ferrite toroids and snap-ons for best results. I use an
old Simpson 374 microameter with a germanium diode across the terminals
(cathode to plus terminal); it makes a good RF sniffer...

73,
Drew
AF2Z

On 07/16/16 08:28, Kevin - K4VD wrote:

> Hi Howard and thanks for your explanations and patience. I need to do some
> more testing a little later on with the KX3 on the RS-50. If I remember
> right, I could hear the hum and hiss from the RS-50 only when the antenna
> was attached. I think that goes along with what you are saying and I just
> need to wrap my mind around that. I am prepared to deal with RF issues
> while transmitting but not so prepared to think the problem could show up
> during receive also.
>
> So far I've added the NI4L HF Choke/Line Isolator just under the BALUN at
> the feedpoint and another just at the rig. I've also added a few snap-ons
> to the DC cord between the RS-50 and the radio at the RS-50 side. I want to
> add more as soon as I can find the rest of them or possibly replace them
> with the 2.4" ferrites at your site.
>
> After doing the above I've noticed my tuning points have shifted a bit. I
> need to get the analyzer on it to see by how much. I also *maybe* noticed a
> reduction in noise on the Flex but to tell you the truth, I never really
> noticed it on the Flex, only the KX3 made it obvious being able to switch
> from battery to external power supply.
>
> I need to do a little more testing if I can find the time this weekend. I
> see the 2.4" ferrite core on your website and will probably place an order
> for a couple/few. Does something like this go on each end of a line or do I
> pick an end?
>
> Thanks again,
> Kevin
>
>
>

Jim Brown-10

Re: Power Supplies

Drew,

Forget your field strength meter and 1) concentrate on providing a
decent counterpoise for your antenna so that return current flows on
that counterpoise rather than ground wiring inside your shack; and 2) on
killing Pin One Problems in the equipment in your shack. You have high
field strength in your shack because the antenna ends at your shack, and
because it is working!

Study k9yc.com/RFI-Ham.pdf

73, Jim K9YC

On Sat,7/16/2016 8:26 AM, Drew AF2Z wrote:
> I have an endfed wire antenna for the low bands so there is RF in the
> shack which needs to be managed. In such a case a field strength meter
> is handy in figuring out how to arrange equipment, cables, keyboards,
> etc and placing ferrite toroids and snap-ons for best results. I use
> an old Simpson 37

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Drew AF2Z

Re: Power Supplies

I do have counterpoises: "decent" is another matter. If I had better
shack/antenna choices I wouldn't be using an endfed wire to begin with.
So, the counterpoises, ferrites, ground loop isolators, equipment/cable
arrangement are all part of the solution.

73,
Drew
AF2Z

On 07/16/16 12:04, Jim Brown wrote:

> Drew,
>
> Forget your field strength meter and 1) concentrate on providing a
> decent counterpoise for your antenna so that return current flows on
> that counterpoise rather than ground wiring inside your shack; and 2) on
> killing Pin One Problems in the equipment in your shack. You have high
> field strength in your shack because the antenna ends at your shack, and
> because it is working!
>
> Study k9yc.com/RFI-Ham.pdf
>
> 73, Jim K9YC
>
> On Sat,7/16/2016 8:26 AM, Drew AF2Z wrote:
>> I have an endfed wire antenna for the low bands so there is RF in the
>> shack which needs to be managed. In such a case a field strength meter
>> is handy in figuring out how to arrange equipment, cables, keyboards,
>> etc and placing ferrite toroids and snap-ons for best results. I use
>> an old Simpson 37
>
>

Hank Garretson

Re: Power Supplies

In reply to this post by Jim Brown-10

Counterpoises are good.

Also very helpful is to adjust total length of flattop and feedline to be
an odd multiple of Lambda/4 for the bands of interest. This keeps max RF
voltage peaks out of the shack. Not always convenient to do if you want
multiple bands.

73,

Hank, W6SX

On Sat, Jul 16, 2016 at 9:04 AM, Jim Brown <[hidden email]>
wrote:

>
> Forget your field strength meter and 1) concentrate on providing a decent
> counterpoise for your antenna so that return current flows on that
> counterpoise rather than ground wiring inside your shack; and 2) on killing
> Pin One Problems in the equipment in your shack. You have high field
> strength in your shack because the antenna ends at your shack, and because
> it is working!
>
> Study k9yc.com/RFI-Ham.pdf
>
> 73, Jim K9YC
>
> On Sat,7/16/2016 8:26 AM, Drew AF2Z wrote:
>
>> I have an endfed wire antenna for the low bands so there is RF in the
>> shack which needs to be managed. In such a case a field strength meter is
>> handy in figuring out how to arrange equipment, cables, keyboards, etc and
>> placing ferrite toroids and snap-ons for best results. I use an old Simpson
>> 37
>>
>

Vic Rosenthal

Re: O.T. Tuning a Counterpoise

In reply to this post by Drew AF2Z

I am thinking that if you make the wire more than 1/4 wavelength at the lowest frequency, all you would need to tune it would be a variable capacitor.

Vic 4X6GP

> On 16 Jul 2016, at 20:39, Ron D'Eau Claire <[hidden email]> wrote:
>
> One approach to reduce "RF in the shack" using an end-fed wire is to
> resonate the "counterpoise" for the band you are using. MFJ made just such a
> "tuner" (model 931 IIRC) but any tunable L-network will work. The idea is to
> adjust the "tuner" for maximum current flowing into the counterpoise
> (meaning the counterpoise is offering the lowest possible impedance to the
> equipment it is connected to.) I have successfully used that in a 2nd story
> apartment feeding an end-fed wire running outside. I know one Ham who bought
> the MFJ box and found it worked FB.
>
> For a homebrew "counterpoise tuner" you'll need an RF ammeter but a good
> cheap one is an incandescent flashlight bulb in series where the
> counterpoise connects to the rig chassis. Tune for the counterpoise for
> maximum brightness with the rig running at the lowest power that will light
> the bulb, then short-circuit the bulb for higher power. Of course, the
> adjustments will interact with the tuner settings for the end-fed wire. But
> the "tuning" of the counterpoise is usually broad enough (low-Q) that noting
> the settings for each band you can return to them without doing the whole
> retuning thing again. (The MFJ box my buddy bought has an ammeter built in.)
>
>
> My "counterpoise" was a thin white wire run around the baseboard of the
> shack and down the hall - about 30 feet total. White wire + apartment white
> wall = invisible counterpoise. Worked FB 40 through 10 meters.
>
> While that will reduce the RF voltage on the rig itself, you will be sitting
> in a high-level RF field from the end fed wire, which limits your maximum
> power to meet radiation exposure limits, depending upon how far from you the
> antenna is located and the band you are using.
>
> 73, Ron AC7AC
>
>
>
>
>
> -----Original Message-----
> From: Elecraft [mailto:[hidden email]] On Behalf Of Drew
> AF2Z
> Sent: Saturday, July 16, 2016 9:30 AM
> To: [hidden email]
> Subject: Re: [Elecraft] Power Supplies
>
> I do have counterpoises: "decent" is another matter. If I had better
> shack/antenna choices I wouldn't be using an endfed wire to begin with.
> So, the counterpoises, ferrites, ground loop isolators, equipment/cable
> arrangement are all part of the solution.
>
> 73,
> Drew
> AF2Z
>
>
>
>> On 07/16/16 12:04, Jim Brown wrote:
>> Drew,
>>
>> Forget your field strength meter and 1) concentrate on providing a
>> decent counterpoise for your antenna so that return current flows on
>> that counterpoise rather than ground wiring inside your shack; and 2)
>> on killing Pin One Problems in the equipment in your shack. You have
>> high field strength in your shack because the antenna ends at your
>> shack, and because it is working!
>>
>> Study k9yc.com/RFI-Ham.pdf
>>
>> 73, Jim K9YC
>>
>>> On Sat,7/16/2016 8:26 AM, Drew AF2Z wrote:
>>> I have an endfed wire antenna for the low bands so there is RF in the
>>> shack which needs to be managed. In such a case a field strength
>>> meter is handy in figuring out how to arrange equipment, cables,
>>> keyboards, etc and placing ferrite toroids and snap-ons for best
>>> results. I use an old Simpson 37
>
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Phil Wheeler-2

Re: O.T. Tuning a Counterpoise

In reply to this post by Drew AF2Z

Thanks, Ron. You just reminded me that I have an
MFJ-934 (ATU with artificial ground) stashed
somewhere.

No real need for it just now, but who knows? Now
I just need to find it!

73, Phil W7OX

On 7/16/16 10:39 AM, Ron D'Eau Claire wrote:

> One approach to reduce "RF in the shack" using an end-fed wire is to
> resonate the "counterpoise" for the band you are using. MFJ made just such a
> "tuner" (model 931 IIRC) but any tunable L-network will work. The idea is to
> adjust the "tuner" for maximum current flowing into the counterpoise
> (meaning the counterpoise is offering the lowest possible impedance to the
> equipment it is connected to.) I have successfully used that in a 2nd story
> apartment feeding an end-fed wire running outside. I know one Ham who bought
> the MFJ box and found it worked FB.
>
> For a homebrew "counterpoise tuner" you'll need an RF ammeter but a good
> cheap one is an incandescent flashlight bulb in series where the
> counterpoise connects to the rig chassis. Tune for the counterpoise for
> maximum brightness with the rig running at the lowest power that will light
> the bulb, then short-circuit the bulb for higher power. Of course, the
> adjustments will interact with the tuner settings for the end-fed wire. But
> the "tuning" of the counterpoise is usually broad enough (low-Q) that noting
> the settings for each band you can return to them without doing the whole
> retuning thing again. (The MFJ box my buddy bought has an ammeter built in.)
>
>
> My "counterpoise" was a thin white wire run around the baseboard of the
> shack and down the hall - about 30 feet total. White wire + apartment white
> wall = invisible counterpoise. Worked FB 40 through 10 meters.
>
> While that will reduce the RF voltage on the rig itself, you will be sitting
> in a high-level RF field from the end fed wire, which limits your maximum
> power to meet radiation exposure limits, depending upon how far from you the
> antenna is located and the band you are using.
>
> 73, Ron AC7AC

Drew AF2Z

Re: O.T. Tuning a Counterpoise

In reply to this post by Drew AF2Z

Tks, Ron- I'll keep that in mind. My counterpoises lie on a flat roof
adjacent the shack. I've never tried to tune them other than initially
cutting them to theoretical best length; I suppose they could be better...

73,
Drew
AF2Z

On 07/16/16 13:39, Ron D'Eau Claire wrote:

Kevin - K4VD

Re: Power Supplies

In reply to this post by Kevin - K4VD

A follow-up to the situation.

I purchased a PWRgate PG40S. On one side I have a marine battery. On the
other side I've got an Alinco DM-330MVT. In the middle is the KX3 and the
Flex. Only one has an antenna at any time.

I added a line isolator right below the BALUN of the OCF and another one
right at the rig input.

At this point there is no difference in the noise level on the KX3 when
comparing internal batteries vs the power setup described above. The Flex
is also not showing anything of concern on the waterfall.

I was (and maybe still am) a little skeptical about both the Alinco
switching power supply and the PWRgate which I think is just the switching
portion of a switching power supply? So far they do not seem to be
generating noise. I'll have to give it some time to see if any snakes come
crawling across the waterfall.

Remaining work...

I'm calling things 80% done and getting back to normal operation. I want to
add some more clip-ons to power cables as soon as I can remember where I
put them all. I need to tear into the RS-50 and see if I see anything
obvious and if not, dig deeper with the o'scope and meter and actually do
some troubleshooting. If I get it working right then I have a good backup
or loaner supply. If not... who knows. I also need to continue reading the
RFI document. There's a ton of information in it and I'm working to
actually understand what I'm reading instead of just using it as a
cookbook. A more balanced antenna - even a Hex Beam - might be on the wish
list.

Thanks for all the help and guidance. I'm feeling pretty good that things
are working well. The QRP Foxhunt is tomorrow night. I hope to be able to
blame my anticipated poor performance on atmospheric conditions and not
equipment noise.

73!
Kevin K4VD
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Grant Youngman-2

Re: Power Supplies

The PWRgate is just basically Schottky steering diodes used to direct power from one terminal to another. It does not generate noise …

Grant NQ5T

> I was (and maybe still am) a little skeptical about …. the PWRgate which I think is just the switching
> portion of a switching power supply? So far they do not seem to be
> generating noise. I'll have to give it some time to see if any snakes come
> crawling across the waterfall.
>

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Kevin - K4VD

Re: Power Supplies

Thanks Grant. I thought there'd be a little more inside for charging the
battery. I did a quick look for schematics on Google but didn't find
anything.

Kev

On Wed, Jul 20, 2016 at 6:12 PM, GRANT YOUNGMAN <[hidden email]>
wrote:

> The PWRgate is just basically Schottky steering diodes used to direct
> power from one terminal to another. It does not generate noise …
>
> Grant NQ5T
>
>
> > I was (and maybe still am) a little skeptical about …. the PWRgate which
> I think is just the switching
> > portion of a switching power supply? So far they do not seem to be
> > generating noise. I'll have to give it some time to see if any snakes
> come
> > crawling across the waterfall.
> >
>
>

Richard Fjeld-2

Re: Power Supplies

In reply to this post by Kevin - K4VD

Kevin,
I will be interested in anything you find. I have a RS-50M and I am not
aware of any noise as you describe. It may be my hearing.

I do have a line isolator in-line left there from the days when I had a
G5RV. That is the only time I have known of RFI. It was pretty bad.

Dick, n0ce

On 7/20/2016 5:03 PM, Kevin - K4VD wrote:

> A follow-up to the situation.
>
> I purchased a PWRgate PG40S. On one side I have a marine battery. On the
> other side I've got an Alinco DM-330MVT. In the middle is the KX3 and the
> Flex. Only one has an antenna at any time.
>
> I added a line isolator right below the BALUN of the OCF and another one
> right at the rig input.
>
> At this point there is no difference in the noise level on the KX3 when
> comparing internal batteries vs the power setup described above. The Flex
> is also not showing anything of concern on the waterfall.
>
>