Re: [Elecraft] Current Flow on Copper Strips - a Question
What's more appropriate for coaxial building entry grounding management? This wide-strap, allegedly low inductance, approach... https://www.comm-omni.com/polyweb/images/pb.jpg ...or this more R56 approach... http://www.radio2way.net/MGB.jpg ? 73 John, kx4o On Fri, April 27, 2018 02:21, Wes Stewart wrote: > "When skin effect is present, the current is always redistributed over > the conductor cross section in such a way as to make most of the current > flow where it is encircled by the smallest number of flux lines. This > general principle controls the distribution of current irrespective of the > shape of the conductor involved. Thus, with a flat strip conductor (figure > reference not shown) the current flows primarily along the edges, where it > is surrounded by the smallest amount of flux, and the true or effective > resistance will be high because most of the strip carries very little > current. (A reference to the missing figure) makes clear that it is not > the amount of conductor surface that determines the resistance to > alternating current but rather the way in which the conductor material is > arranged." > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dish/Direct TV RFI?
You are, of course, absolutely correct Jim. Know that one model of the sat receiver uses an RF remote of some sort that many think is the culprit. Sadly the response from the, understandably RF clueless, sat help lines is kind of like going to a doctor with the plea "it hurts to do this" and response of "well don't do that." I suspect nothing will change much until a 40m signal affects the sat systems of the ham's neighbors resulting in a Part 15/97 brawl. On Wed, March 14, 2018 22:47, Jim Brown wrote: > Problems like this are the result of design defects in the cable modem. > It should be possible to solve problems of this sort by winding multiple > turns of both the coax and the power cable #31 or #43 Fair-Rite toroids. > See > > http://k9yc.com/KillingReceiveNoise.pdf > > for part numbers and guidelines for winding. While the app note discusses > RX noise radiated from gear like this, the cures are the same > for both. > > AND -- because it's the result of a defective modem (i.e. a bad design), > ALWAYS call the vendor and tell them to fix it. > > 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Dish/Direct TV RFI?
I have personally seem a 40m signal change the channels on our Direct TV setup. This is, unfortunately, a common problem... https://www.google.com/search?q=direct+tv+amateur+radio+changes+channels=direct+tv+amateur+radio+changes+channels John, kx4o On Wed, March 14, 2018 12:56, Reed wrote: > Has anyone had trouble with RFI, receive or transmit, with Dish or > Direct TV. I have cable through Comcast & tired of their rate increases > so thought I give satellite a try since looks like more bang for the buck. > > Thanks, > > Reed W4JZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Experiences using a portable HF loop
Small loop efficiency is relatively dismal, but as G8HQP once said concerning this topic... That would depend on what you mean by 'efficient.' Probably not efficient in the usual engineering sense of power out vs. power in, but perhaps 'efficient' in the common meaning of being able to do the job of radiating something from a small space. My small space and portable (or to some lugable) example here... http://www.hamradio.me/antennas/small-loop-hf-antenna.html ...performs surprisingly well on 40m despite the losses, hence supporting G8HQP's premise. An additional important thing to keep in mind is the seriously high E and H fields around these things even with QRP power. The H field especially exceeds MPE limits a couple meters out along a line through the plane of the loop. Some folks operate next to their loops... not me man. Small loops are an enigma at first, but part of the fun is unraveling the mystery through experimentation. Join us. 73 john, kx4o On Sat, April 22, 2017 01:24, Eddy Avila wrote: > Greetings all, I'm curious to hear from anyone using a portable HF > magnetic loop. I've read the theory behind them so I'd like to hear your > opinion about them? How efficient these antennas are, especially running > qRP. > > > Thanks all, > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] [KX3] Adding TX/RX "Relay" to KX3 Operation
All, Oh the things that come up for Field Day with just weeks left to prepare. Say someone commits to bringing a "mighty-fine" RX only electrically steerable antenna of some sort to field day 2016. Not wanting to be forever mechanically switching between TX and RX antennas... How would you approach adding an automatic TX/RX swtiching capability to a KX3 operating QRP? Would you consider some sort of "diode" switch or stick with good ole mechanical relays? I have my thoughts, but thank you all in advance for yours. John, kx4o __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] This will effect pilots and Hams throughout the Western US
Time to refit my Rose bag for a sextant and charts... and a fine watch? John, kx4o On Fri, June 10, 2016 20:03, Fred Townsend wrote: > > This Is Likely Why The Navy Is Causing A Massive And Mysterious GPS > Outage > In The Western US - The Drive > > > http://www.thedrive.com/the-war-zone/3865/this-is-likely-why-the-navy-is- > cau sing-a-massive-and-mysterious-gps-outage-in-the-western-us > > Fred, AE6QL > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Bonding KX3/PX3/KXPA100 - any examples?
I wish I had more pictures, but this one... http://www.hamradio.me/wp-content/uploads/2015/07/20150627-009.jpg ...from my FD article... http://www.hamradio.me/activities/kx4o-1b-battery-va-field-day-2015.html ...shows a strap of copper running behind all the gear shown roughly following K9YC's advice. I used some 1/4 inch braid I found somewhere, crimped some lugs on each end and connected each chassis to the strap. The RigBlaster connects via one of its case mounting screws. The PX3 and KX3 connect via one of the chassis thumbscrews. Not shown is a 5V linear regulator to power my USB splitter from a Pb equiv. battery. It uses the copper strap as the heatsink. This works quite well. I've never encountered the noisy conditions that Jim's steps help mitigate, but I think it is a good idea regardless. John, kx4o On Fri, June 3, 2016 14:14, David Orman wrote: > Hi, > > > After reading Jim/K9YC's helpful documentation, as well as various > suggestions on this and other lists, it's clear bonding equipment together > is a good plan. I'm curious to see _how_ people have done this with > their KX3/PX3/KXPA100 combinations, as in what points (thumbscrews for the > feet? something else?) they are bonding together, using what kind of > braid/wire, and how they've got everything put together in general. I > searched Google with minimal luck finding any such examples, and I think > it would be useful for the group to see some good examples of how things > should be done. > > Thank you, > David/K5DJO __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KX2 haiku (attempt )
The Haiku format: Contains seven five seven 'syllables' okay? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KX3 IQ Outputs - What to expect?
On Tue, March 17, 2015 05:16, Peter Lambert wrote: Thanks Peter. Good clues and I will have a look. Schematics printed and heading to work where we maintain an electronics lab that is an anti-static wonderland. I wonder, though, if there isn't some external forensics to try first. I mean if the I or Q are not proper at the points you mention, there should be some evidence in the operation right? Although I do note proper I an Q levels when the VFO is close to the test frequency and within the demodulating bandwidth. Elecraft has been sent a note along with o-scope plots of the IQ out connector, but I will perform a visual inspection of the spots you mention. John Hello again John, Looking at the schematic, any difference you see should be so slight that you'd not make comment on it. If it were me I'd take a look at the inductors LD-LG (on page 4 of the schematic) to see if there is the possibility of one of them being shorted. I haven't had look at these but it's common to twist the terminating wires together - a likely spot for a short. I'd stick the CRO on the output of each of the 4 inductors (where the circuit shows RX_I and RX_Q and the opposite side of C1K and C1L) all the levels here should be pretty much identical. Of course you can only expect this over the range of +- 96kHz or so. 73's Peter VK4JD __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KX3 - Power out vs. ALC bars
Thanks Walter. I think I understand now. What is the loop bandwidth of the power control loop? Thanks. John, kx4o On Mon, March 2, 2015 05:54, Walter Underwood wrote: No. Most likely the power varied as it was hunting for the right level. It probably started low then increased power slowly throughout each transmission. wunder Walter Underwood wun...@wunderwood.org http://observer.wunderwood.org/ (my blog) On Mar 1, 2015, at 9:44 PM, John k...@hamradio.me wrote: Is it safe to say my very low input audio level was compensated by the KX3's power control loop to yield 5 watts out (the actual radio power setting)? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KX3 - Adjustable RTY/PSK Idle Timeout
Hi Don.
I'm aware of the IM feature and I do make use of it during casual use.
However, I'm trying to make the most of the CAT sending capability of the
KX3 and USB cable in a contesting/event situation (like Field Day) using
N1MM, but without audio interfacing.
For N1MM macros can one embed this IM into a KY command string without
it becoming an I followed by an M? I did try this, but it just comes out
I and M as I suspected it would. On another KX3 group, Wayne mentioned
other methods including sending 0x04 and using a | symbol. Neither seems
to work in the N1MM macro context.
The good news is I have successfully programmed the macro to terminate
right after sending using this N1MM macro string designed for the VaQP...
F1 Run CQ,{CATA1ASC KY CQ VQP CQ VQP;}{CATA1ASC KYW DE {MYCALL}{MYCALL}
QRZ;}{CATA1ASC RX;}
This nicely waits to execute that last RX command till after the last
character is sent to the KX3, but the RX executes immediately cutting off
that last character mid transmit. Somewhere somehow I need to introduce a
delay between the last character sent and the execution of the RX command
long enough to finish transmitting that last character in RTTY or PSK31.
As I understand it, a RTTY character takes about 165 milliseconds to
transmit and the worst case PSK31 character (10 bits) takes about 313
milliseconds.
There are several potential solutions.
First I would never want the RX command to change since having something
that instantly takes the KX3 out of transmit is a good thing. So a new
command (i.e. RXABE - RX after buffer empty?) that puts the KX3 into
receive only after the character buffer has completed transmission might
be nice.
I suspect the simplest solution of all is for me to eliminate the RX
command in the N1MM macro string and the KX3 provide a method to adjust
that 4 second idle time to user preference. This could be:
DATA_IDLE_TIME: 4s (default), 2s, 1s, 0.5s, etc.
...or maybe...
DATA_IDLE_TIME: 4s (default), ASAP
Where ASAP = 200 milliseconds for RTTY and 400 milliseconds for PSK31
At this point, I'd be happy with a 1 second idle time option to complement
the 4s ragchew default.
All hail software defined radios where feature requests like this actually
have a possibility of implementation.
John, kx4o
On Wed, February 25, 2015 05:08, Don Wilhelm wrote:
John,
Send the IM character to stop transmission immediately. That is sent as
a prosign would be - dit dit dah dah, and not as 2 letters. If you have
trouble sending it correctly, think of it as sending the numeral 2 without
the last dah. You can also imbed that character in memories. It will not
send anything in CW, but will end transmission immediately in data modes.
73,
Don W3FPR
On 2/24/2015 9:32 PM, John wrote:
Hello,
Is the default 4 second idle timeout in the KX3's built-in keyer
RTTY/PSK31 transmit feature something we can adjust to, say, 1/2
second? It seems all too often a response is well underway by the time
the transmission ends in quick QSO conditions.
__
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to arch...@mail-archive.com
[Elecraft] Toughness
Field Users, Which Elecraft products stand up best to knocks, bumps, etc. seen while fielding a station? Thanks. John, kx4o __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Toughness
Understood about the external features Ingo and good advice. My primary concern is over the internal soundness of products touted as portable. Thruhole and surface mount components are quite sturdy. Edge and header connectors are, well, good enough most times. My primary concern are those round masses held with wisps of wire... toroids. Has anyone ever seen toroids come loose and turn their rig into a maraca? John, kx4o On Mon, April 9, 2012 13:59, Ingo Meyer, DK3RED wrote: I think the elecraft transceiver are all robust for fielddays or portable use. But all transceivers have knobs, jackets and displays, which shold be sheltered during transportation. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Toughness
The ultimate goal is backpacking a 10W K2 on certain trips. Thanks to all for the inputs thus far. It sounds like things should be fine so long as common sense is applied to packing plus no drop kicking of the pack. John, kx4o On Mon, April 9, 2012 19:56, Mike Heitmann wrote: I can vouch for that. I backpack with my KX1 and have never had a problem with it. It's been a workhorse for me, and will continue to serve in that capacity until my KX3 arrives (although, I'm beginning to wonder if that will ever really happen). I also have a K2 with the 100W and and auto tuner in a separate enlcosure. Never a problem with them either. I've not ever taken the K2 backpacking but I have used it for fixed portable ops and for demos and had no trouble with it. They're pretty tough when properly assembled. Mike, N0SO is fragile, modern electronics is not). I have over 600 repairs to my credit and have never seen a broken toroid wire. If the toroids are mounted with the leads snugged down, they will not move substantially after soldering. 73, Don W3FPR __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Supply Voltage Range Elecraft K2 transceiver
Hi Rolf, Judging from the K2 schematic, there is no over-voltage protection, save for the SB530 (D12) reverse protection diode which, in normal hookup, won't do much until the bus hits ~30V; This is clearly meant for reverse protection only and really that's taken care of with D10. I guess D12 is there in case someone drives power reversed into P3. Smart. A related question concerning whether the K2 can handle high voltages is... Did the K2 designers have automotive power systems in mind when designing the rest of the circuitry that touches their 12V internal bus? This implies 9-15 nominal voltage, as their spec. sheet suggests, but also implies the ability to handle the addition of power bus ripple up to ~16.5 Volts peak and temporary spikes/surges up to 25 volts or more... the real world of vehicle power busses. 9-18 Vdc is the usual nominal rating for anything that connects to a 12V automotive power bus. A quick glance at all the parts touching 12V or 12V IN finds items with ratings of 20V (6V Reg.), 22V (Audio Amp), 25 V (Finals), 26V nom. 40V peak (8V reg.), etc. I suspect nothing will punch through those higher rated parts when run at 16V. However, I would have concern over the power dissipation of those finals and voltage regulators when running more than 15V. Given the voltage ratings of the K2 parts on the 12V bus, I wouldn't connect a K2 to an automotive power bus without a peak clamping circuit inline... similar to D28 in the K3 design. However, you are asking about 4S Lithium Battery Packs. Until someone runs a stress analysis on the key warm parts in the K2, I would not run it beyond 15V. You can do what other 4S Lithium converts from many industries (who face this exact same problem) do... put a low dropout regulator in series with the pack and set it to 14V or so. This ensures you are not pushing power dissipation in the K2's parts beyond their design limits. John, kx4o On 1/12/12 4:49 AM, rolf wrote: Elecraft specifies the voltage supply range for the K2 transceiver to 9-15 Volts. snip Question: Keeping the RF power output and the DC Current of the K below the maximum limit, is it possible to apply a supply voltage exceeding 16 V without causing a failure to the electronic components in the K2? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [KX3] LiPol battery pack and KX3 - voltage vs output
Being a switching circuit topology, boost circuits' efficiencies can well exceed 50% and often 80%. Some are in the nineties. You can think of them as a constant power circuit which will tend to consume more current as the voltage drops to deliver the same power to the load. What this means to your battery life is hard to say. Lithiums can maintain a decent current till the voltage dives off the cliff so your idea has merit. However, the boost circuit is a switching circuit and generates a ton of noise that requires special care in design to reduce. It's not impossible to achieve, but not easy. For simplicity's sake, you are likely to be better off adding one more cell in series and using a linear low dropout (LDO) regulator to ensure the voltage never exceeds 15V or whatever Elecraft says is the practical max. As the battery voltage lowers below 15V+headroom the voltage will track downwards with a small loss. LDOs sometimes misbehave (oscillate) at the point where the Vheadroom drops below regulation, but the lower loss is usually worth it. Lots of choices exist including just living with the 3 cell voltage. The switcher is likely too noisy. The LDO allows for max voltage longer. A plain old linear regulator with 2V+ headroom might work too, but you are wasting a bit more power. John, kx4o I'm not an EE so maybe someone who is can answer my question. A boost circuit certainly cannot have 100% efficiency, but how efficient would it be? Some of the energy in the battery will be consumed by the boost circuit and not available to the radio. So then how does one evaluate whether using a boost circuit will get you more operating time or not? I presume it must have something to do with the flatness of the battery's discharge curve and also whether you need more than 5 watts. David K0LUM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] OT Quality UHF Connectors
All, Does anyone know a good source of UHF connectors? If so, please respond off list with Make, Model and, if you have it, Vendor. Thanks. John, kx4o __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K2 - Board Cleaning and Conformal Coating
All, Being in the electronics biz, we usually wash boards post assembly with the usual products and in accordance with IPC610, etc. Often, the boards are sprayed with conformal coating: Some to handle condensing environments and others just because someone wanted it. My operating locations will include salty beaches and moist mountains. I couldn't find details in the K2 manual concerning these steps. I did find a few posts in old Elecraft archives, but need to ask... Are there any components used in the K2 boards that will not tolerate typical board washing procedures? (Most modern components expect this step, but some don't - often switches) Is there any reason not to conformal coat the boards once complete? (Cost is no object to make this last a long time in beach environments) Thanks. John __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Battery Charger Voltage High?
Keep in mind automotive power busses can and do have steady state voltages over 15V and even 16V when you include allowable ripple. Power busses are a terrible terrible place. Assuming the K3 designers' had in mind a car's electrical system, the choice of the BZW50-15 (in the QRP version) puts the effective clamping voltage above 16.6 volts and even then it is a gradual rise in clamping action vs. voltage. Then if you take away the 1/2 volt or so drop from the reverse protection, the net bus voltage inside can be more than 16V steady state and even higher for brief surges. Yuck. Clearly the designers' know about real-life DC power busses and designed the rest of the radio to take the abuse with some margin and rely on that clamp diode to blow the fuse should things get hopelessly ridiculous on the power source. So the good news is the K3 should be able to take the smack in the face from what I assume is a PWM style battery charger when in trickle mode. However, I would not make a habit of it and heed others' advice about staying within the 15V limit with a good DC power supply or charge with the radio disconnected. It should have less electrical noise as a side benefit. John Dick, Yes, 16 volts is too high. There is a 15 volt zener diode right at the DC input of the K3 which should limit the voltage to the K3 at 15 volts (or until that zener diode is damaged). The charger may be dropping into the bulk charge output rather than staying in the trickle charge state. You may be better off with a simple trickle charger than a 2 or 3 state battery charger. 73, Don W3FPR On 5/26/2011 1:58 PM, r...@aol.com wrote: Hi Guys, I'm operating from a portable location and using a 12-volt automobile battery with my K3. To keep the battery charged I'm using a Schumacher 15-Amp Charger/Maintainer that automatically switches to Trickle Charge when the battery is charged. My concern is that when the charger is connected the battery voltage is peaking at 16.0 volts. The K3 manual says maximum voltage is 15 volts. Do I need to be concerned about powering the K3 with 16.0 volts? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] XV432 Oscillates with Amp connected
All the suggestions about trying different cable lengths are good thoughts to help find the sweet spot of compatibility between the XV432 output circuit impedance and the Henry input impedance. Folks on the repeater-builder group talk about this very issue often; Of course in their case they are concerned about the transmitter feeding a reactive duplexer assembly. Oscillations don't seem to be the issue presented, rather, the tendency of the transmitter output stage to produce other by-products when forced to feed a reactive load, such as a narrow band-pass duplexer, causes unhappiness in the transmitter. Spurious signals are the result. The oft touted simple cure proposed is try different lengths of cable between TX and Combiner. The more professional solution is to place an Isolator between the TX and the Amp during transmit. One example is shown here... http://www.rflambda.com/pdf/isolator/RFLI101M40M50.pdf This way, the TX only ever sees a nice infinite coax assuming, of course, the third port is properly terminated into 50 ohms. Of course you need to receive as well and the isolator won't help with that by itself. So all I have done here is to propose a workable, but unwieldy and expensive solution if, in fact, the cause of the oscillations is impedance issues between the XV432 output stage and the Henry input stage. The point is impedance issues between a Source and Load can cause the source to not play nice. Let's hope your problem is just a feedback path solved with chokes. John Good day, I'm working with the XV432, Flex 1500 and Henry 2004A Amp. The rig, xvrtr and amp PTTs are sequenced. Hoping somebody might have been down this path before and has a solution. If I connect the transverter output to the amp (or different pieces of open coax) and key the transverter, the power meter goes full scale and I see an oscillation on the spectrum analyzer. The frequency of the oscillation varies with the load. (i.e. amp connected or different lengths of coax) If I connect the XV432 to a 50 ohm load, no oscillations and all works well. I ran through the alignment procedure again with the XV432 connected to a 50 Ohm load. All the voltages look right and the tuning is smooth. (e.g. 20mV Quiescent Current Adjustment, TP3/TP4) It's obvious the XV432 is happy into 50 Ohms, but not into impedances that wander from 50 Ohms. BTW, I have added all the mods as per the Elecraft website. Any ideas? 73's Stu2 W7IY __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] K2 and K3 Microphone Input Impedance
Wayne et al. I am surveying various rigs to see what their microphone input impedance values might be. I note the K3 schematics show just about every audio path including the microphone's path terminated in 10k ohms or so. In the KSB2 I see 1k ohm (or 180 ohms if /ATTEN is asserted). Was there a compelling reason for having different termination values, 10k vs. 1k, between transceiver model lines? Thanks. John __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Overvoltage Protector Update
Nice circuit. Since this is meant to help protect the K3 from faulty power supplies, this begs the question of what abuse can the K3 (or K2) take from the power bus. As an automotive power bus is a terrible awful place, will the K3 design tolerate these typical values found on a vehicle power rail: - Steady State Voltage between 12.5 to 15 Vdc, - Upper and lower ripple of +/- 1 Vpeak riding on the Steady State values, - Surge values between 9 and 20 Vdc for 600 ms, - Spikes of +/- 125 Volts peaking for 70 uS falling to steady state levels after 1 ms, ? I've updated the drawing to include construction notes and a mechanical sketch: http://www.ssec.wisc.edu/~scotte/hr/OVP.pdf The large heat sink, I know, will seem to some like overkill. To me, an extra 20 bucks seems like cheap insurance. See the notes. As W8JI notes, a simpler circuit just uses a zener diode to drive the SCR. I chose the more complex version to allow the trip point to be set close to the operating voltage. The K3, for example, has a maximum rating of 15.0 V, too close to 13.8 for the simpler circuit. At the moment, all the parts are available from Digi-Key. Scott K9MA On Aug 20, 2010, at 3:00 PM, Scott Ellington wrote: Some power supplies, like the Samlex SEC 1235, have no built-in __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
