+++++++++++++++++++++++ Date: Fri, 13 Jul 2001 19:27:58 -0700 From: "N7SG K7FD" Subject: [Elecraft] TurboCharging the K1/KBT-1 Inspired by a recent visit to the movie theatre and a bag of popcorn, the flick 'The Fast and Furious' got me to thinking. Yes, I know, I know...that IS dangerous. But what if I could add more ooomph to the K1's portable horsepower...just a few more precious volts... If you're curious, check out: http://www.teleport.com/~cqdx/turbo.htm See you on the street, 73 John K7FastDriver +++++++++++++++++++++++ Date: Sat, 14 Jul 2001 18:40:31 -0700 From: "N7SG K7FD" Subject: [Elecraft] re: K1 Supercharger Thanks for the nice comments on the K1 'turbo' mod...hi. It seems quite a few are still waiting for their KBT1's to arrive from Aptos...but are anxious to install the battery option and mod. Last night and today were the first full real test of the battery mod. This is very non-scientific but I turned the radio on from 7:30pm to 1am last night, then today 11am to 6pm. That adds up to 12.5 hours. At 6:15pm today I got the LO BAT warning as the voltage dipped to 8.2v on transmit. My use of the K1 would be termed 'light to moderate', listening a lot, cq'ing a tad bit at 3.5w, and contesting a smidge, too. My NiMH's are brand spanking new, so I'm hoping they'll even get better as the 'get seasoned' over a couple of charge sessions. I'm also using el cheapo brand batteries...maybe with brand name batteries I'd do even better? By the way, the turbo mod DOES fit with both options installed...NB and KAT1. 73 John K7FD, http://www.teleport.com/~cqdx/turbo.htm +++++++++++++++++++++++++++ Date: Sat, 14 Jul 2001 21:28:40 -0700 From: "Glenn Maclean" Subject: Re: [Elecraft] re: K1 Supercharger I just completed John's K7FD turbo mod adding the two additional Radio Shack battery holders to my K1. John is a genuis for coming up with this idea. I think Eric and Wayne should make this mod part of the KBT1 option kit. There is plenty of room at the back of the top cover for the two additional battery holders. I now get a voltage reading of 13.6 volts or so. I am using ten of the green Radio Shack NiMh 1600mAh batteries inside my K1. I am leaving on a trip Monday and will be using my K1 with the batteries every night from a hotel room. I will let you guys know how long the batteries last before having to recharge. Glenn WA7SPY +++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 01:16:10 -0700 From: "N7SG K7FD" Subject: Re: [Elecraft] TurboCharging the K1/KBT-1 This is true! Ten Alkalines might be pushing the envelope...the NiMH's I have are measuring approx 1.38v per battery...so works out OK. Good point, however...I wonder 'how much' over 15v the K1 could go without blowing a piston? 73 John K7FD >John, > >There are battery types (alkaline?) which will exceed 1.5 volts per cell >.. so 10 will exceed tha max voltage of 15 volts for which the K1 is >rated. I think there is no problem with NiMH, though. > >73, Phil W7OX +++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:09:39 -0700 From: Wayne Burdick Subject: [Elecraft] Re: K1 Supercharger N7SG K7FD wrote: > > Thanks for the nice comments on the K1 'turbo' mod...hi. It seems quite a > few are still waiting for their KBT1's to arrive from Aptos...but are > anxious to install the battery option and mod. Hi John, Interesting mod (adding two more batteries), and nicely executed. We considered doing something like this initially. But after doing lab and field tests, we concluded that 8 NiMH cells provide a very reasonable supply voltage for typical K1 field operation. The battery pack stays around 9.0-9.5 V during over 80% of its charge, and this voltage is an ideal match for a power level of 2 to 3 watts, based on calculations of the PA collector impedance. Recall that the K1 has a 1:4 transformer at the PA output. This dramatically increases the power output available from low voltages. In fact, on my K1, which is not modified in any way, I can get over 6.5 watts output on 40 meters and about 5 watts on 20 meters at 9 volts. So there is no techincal requirement to provide the K1 with a 12 V or higher supply. The double-regulation of the VFO, combined with the initial low-dropout 8V regulator, ensures stable operation from voltages down to near 8 V. What your mod offers is the ability to operate at higher power levels (when necessary), and also some increase in operating time as the batteries drop below 1 V per cell. However, for NiMH cells, this cell voltage indates that the batteries are near the end of charge anyway, so you won't get a huge amount of extra time just because there are two more cells. Regarding operating time with new batteries: NiMH cells do tend to gain energy density after the first one or two full charge cycles. 73, Wayne N6KR +++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:23:54 -0700 From: Wayne Burdick Subject: Re: [Elecraft] re: K1 Supercharger Glenn Maclean wrote: > > I just completed John's K7FD turbo mod adding the two additional Radio Shack > battery holders to my K1. John is a genuis for coming up with this idea. I > think Eric and Wayne should make this mod part of the KBT1 option kit. There > is plenty of room at the back of the top cover for the two additional > battery holders. I now get a voltage reading of 13.6 volts or so. Glenn, I appreciate your comments, but to emphasize my previous posting, the K1 does *not* require 12 V or more to operate. Because of the 1:4 transformer in the PA, as well as the 8 V low-dropout regulator, the rig will be quite happy at anything over about 8.2 volts. We carefully tested transmit and receive at this voltage level with excellent results. And in my initial field tests, I ran 5 watts on 40 meters and 4 watts on 20 meters over several hours using a typical TX/RX duty cycle. The antenna tuner and noise blanker also perform identically at low and high supply voltages. I think this is partly a case of old habits dying hard. 12 V has been the power supply standard for QRP rigs for so long that the idea of running from a lower voltage takes time to get use to. But consider that many hand-held VHF/UHF FM transceivers and cell phones run on 7.2 V or less! A loy of these units operate at well above 2 watts, and with less efficiency than the K1. The mod may be popular with those who want to run up to the maximum power (7 W) all the time with their K1s, even from the field. But (in my opinion) it is not a required modification or a necessary addition to the KBT1 kit itself. 73, Wayne ++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:26:33 -0700 From: "N7SG K7FD" Subject: [Elecraft] Re: K1 Supercharger Hi Wayne, Thanks for the note. Interesting about higher power vs. longer operating time. I didn't realize the finer points of batteries! HI! I was actually hoping for more 'distance' than higher output, but as you say, higher output may be what I get! What I decided was to boost the output up to 3.5w and hope I could get the best of both worlds - a little more output and a little bit more operating time. In unofficial test results, this seems to be the case so far. 73 John K7FD Wayne sez: >What your mod offers is the ability to operate at higher power levels >(when necessary), and also some increase in operating time as the >batteries drop below 1 V per cell. However, for NiMH cells, this cell >voltage indates that the batteries are near the end of charge anyway, so >you won't get a huge amount of extra time just because there are two >more cells. > >Regarding operating time with new batteries: NiMH cells do tend to gain >energy density after the first one or two full charge cycles. > >73, >Wayne >N6KR +++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:45:44 -0700 From: Wayne Burdick Subject: [Elecraft] Another point regarding the use of 10 cells in the K1 If you're thinking about putting in John's mod (two extra batteries), I recommend that you also add an SPDT switch to *bypass* these two cells. There are two reasons for this: 1. You might have only 8 cells available. AA cells seem to be "quantized" in batches of 4 or 8 most of the time--the physics of this is not well understood ;) 2. You might not have time to charge 10 of them! Here's the scenario: the Radio Shack and other NiMH fast-chargers generally charge 8 cells at a time. If you're in a hurry to charge the cells and hit the road, the last thing you want to do is have to figure out how to safely charge two *more* cells at the last second. But if you don't charge your NiMH cells all equally, all the time, you can end up with odd lots of partially-charged or even over-charged cells. This reduces battery life and can lead to field failures. It is concerns like this, combined with the fact that the K1 works so well with 8 cells, that led us to stick with 8 cells. 73, Wayne N6KR +++++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:49:02 -0700 From: "N7SG K7FD" Subject: [Elecraft] Re: Another point regarding the use of 10 cells in the K1 Good point! This would also allow the use of 8 AA Alkalines...where 10 Alkalines would provide too much voltage...at least by my measurements here. So I DO get to put a real 'TURBO' switch in, cool! :) 73 John K7FD +++++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 10:46:36 -0700 From: "Glenn Maclean" Subject: Re: [Elecraft] Re: K1 Supercharger Wayne, Thanks for the informative discussion on the lower voltage operation. I can see one advantage of the extra batteries is longevity of operation. A good example would be going on a week long back packing trip. I would hope to get longer operation having the extra two batteries. I would run less than 3 watts of course. Thanks again for the KBT1 option it works very well. Glenn WA7SPY ++++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 11:08:00 -0700 From: Wayne Burdick Subject: [Elecraft] Re: K1 Supercharger; KBT1 low-drop protection diode "Brian B. Riley, N1BQ" wrote: > I had bought a Rat Shack 9.6v NiMH pack to use > in my FT-817, but decided to buy one W4RTs One-Plus Power units instead > ... so my thought is to use the RS pack on my K-1, just putting an > appropriate 'tweenie' to go from the RS Molex connector to the back of > the K-1. My question is will that give me less power than the battery > pack in the KBT1? That is to say, is the diode in series with the > internal pack as well as the external power plug? Brian, The KBT1's reverse-polarity protection diode is only in series with the K1's internal battery. The K1 itself also has a reverse-polarity protection diode, which is only in series with the external power supply. However, they are two entirely different diodes, and this has a bearing on your question. The 95SQ015 diode supplied with the KBT1 is optimized for low-voltage use, and drops less than 0.2 V at 500 mA. (It's a very expensive diode, which trades a small increase in reverse leakage for a decrease in voltage drop in battery-powered systems. It's rated at 9 amps.) So, when you use the internal battery, the K1's voltmeter will indicate about 0.1 V lower on receive and 0.2 V lower on transmit than the battery's actual terminal voltage. We felt that the extra expense for this diode was worth it, specifically so you could get the best possible "mileage" from an internal 8-cell NiMH pack. NOT supplying a reverse-polarity protection diode for the battery was never even considered. This is a very important safety feature. And it's much safer to use a series diode than to depend on a shunt diode and a fuse. (The K2--a more expensive rig--actually includes both types of protection.) The K1's normal reverse-polarity protection diode is a more conventional Schottky power type that drops about 0.5 V at 500 mA. The K1 internal voltmeter will indicate about 0.3 V lower on receive and 0.5 V lower on transmit than the external supply voltage. So, to answer your question (finally!), you will get more usable voltage from the K1's internal battery than from an external battery, assuming the two have the same terminal voltage. You could replace the normal K1 reverse-polarity protection diode with a 95SQ015, though, and the two would then be identical. 73, Wayne +++++++++++++++++++++++++++++++ Date: Sun, 15 Jul 2001 11:34:57 -0700 From: "N7SG K7FD" Subject: [Elecraft] ...more KBT1 notes... Wayne and all K1 owners, I could get 6.8w on 40m with just the stock battery pack! So Wayne is on the money about the K1 design being 'maxified' for the 8 cells... ...all this stuff about batteries is very interesting and I really appreciated N6KR jumping in with some 'solid' technical info! One thing that is a definite danger (brought up by W7OX) would be to run 10 AA Alkaline's...and go over the 15v rating of the K1...hope nobody tests that! I am definitely adding a SPDT switch to add flexibility between the original 8 cell pack and the two additional batteries. Thanks again for the note Wayne and your level of support on this... 73 John K7FD > > >From: Wayne Burdick > > >Hi John, > > > > > >Did you ever check your maximum transmit power output level when you >had > > >only 8 cells? As I posted, I could get over 5 watts on both bands at 9 > > >V. With a 12 V supply, and by "tricking" the RF detector, I can get 10 >W > > >out on 40 meters ;) > > > > > >tnx > > >Wayne +++++++++++++++++++++++++ Date: Tue, 17 Jul 2001 01:09:59 +0100 From: Larry Cahoon Subject: Re: [Elecraft] Batteries for K1 At 05:25 PM 07/16/01 -0700, lhlousek wrote: >Each battery holds a certain amount of energy. 10 batteries gives you >10 times as much energy as one. However in the case of the K1, the >energy in the two additional batteries placed in series gets wasted as >heat if you operate at the same power as you could with only 8 >batteries. More or less... Only true if you run the same current in both cases. At a higher voltage - 10 cells - you might be running less current. Check it out. Set the rig at 3 watts or whatever power you want to use and see what current it draws with a ten cell pack and then with an eight cell pack. If the numbers are the same then the extra two cell are a waste. If they are different you know how much longer the ten cell pack will last. Try it both on receive and transmit. I don't see much difference with my K1 set at 2 watts. 73 de Larry............WD3P in MD http://www.qsl.net/wd3p/ +++++++++++++++++++++++++++ Date: Mon, 16 Jul 2001 22:10:47 -0700 From: Wayne Burdick Subject: [Elecraft] K1 batteries -- attempt at a summary I appreciate all the discussion on this topic, which could be the newest black hole ;) To summarize: - - Adding more batteries increases the voltage, not the current. - - Higher voltage means you *can* get more power out, especially on the higher bands. But: you may not want to use higher power when operating portable anyway. (W7ZOI made the 1/2-watt level famous as a good tradeoff between battery weight and communications efficiency. A bunch of us pushed the 2-watt level in the 90's. Now we're pitching 3 watts for use with K1/battery ;) - - Batteries with higher mAhr ratings will last longer, but cost a LOT more, and some of them may be too big to fit in the KBT1 battery holder. Worth the trouble? Maybe not. Radio Shack cells work great. - - 10 cells are a pain because all the fast-chargers are designed for 8. And here's my personal favorite: - - For a given power level (say 2 watts), higher voltage *will* allow you to operate longer, because the transmit current goes down. But it isn't as big a deal as you might think--here's an example: Let's suppose you add 2 batteries (V increases 20%) and that, as a gross approximation, your current goes down 20% at your chosen power level. You'd think, "Aha! I can now operate 20% longer!" Not! Suppose you are actually *key-down* only 20% of the time. That means you're only saving 20% of the current 20% of the time, or an average of roughly (and I do mean roughly!) 4% increase in operating time. Is this worth the addition of two batteries? Maybe not. So my conclusion is this: add two batteries only if you need to in order to operate at your chosen power level on your chosen bands, but *not* because you'll dramatically increase operating time, which you probably won't. If your K1 has low output at 9 V on your chosen bands, see our freshly-posted application note about increase the TX buffer gain! 73 and happy hiking! Wayne N6KR +++++++++++++++++++++++++++ Date: Wed, 18 Jul 2001 19:31:42 -0700 From: "N7SG K7FD" Subject: [Elecraft] Results: K1 Battery Test Well, the mad scientist is at it again at K7FD. The battery torture chamber has been very active this week...and I have some VERY unofficial results from the labor-a-tory. But first, if you haven't yet read Wayne N6KR's take on the 8 vs 10 NiMH cell's for powering a K1, please take a moment to visit http://www.teleport.com/~cqdx/turbo.htm and read what he has to say. His points are valid and your style of operating comes into definite play... ...ok, N6KR disclaimer out of the way, here's what I did and what I found. Tuesday morning, I stuffed **10** fresh 1600 NiMH cells in K1/52 at 7am. Unplugged my key, turned on the rig to 14.060MHz, put headphones in the jack, and set AF at 9am. Then I went to work. The radio stayed ON while I was away. At noon, I ran home, set my power to 3.5w, popped the key in, called CQ 3 times with no takers. Time to go back to work, so again left the rig ON. At 5pm, I got on the radio and began my 'normal' evening radio activities... I had 5 - 8 ragchews throughout the evening, most in the 10 - 20 minute category. Several of you commented on reading the 'battery' thread ;) Then at ***9:20pm***, the 10 pack of batteries died...(i.e., no frequency stability on transmit). So, I got about 14 and half hours of continuous operation, mostly listening...but with a flurry of transmitting in the evening hours. Now for **8** battery torture test/comparison Part II: This morning I went through the same exact fire drill at 7am, but this time with 8 (not 10) fresh 1600mAh cells. Same deal, go off to work, then a few 3.5w cq's on my lunch break but no takers. I get home tonight, and at 5pm start calling CQ...immediately in the log, Dan N0BN/m with a very short qso due to QSB. Then Mike KD5KXF for a short hello. After a brief break for dinner, Dan N0TK answers my CQ. Then at ***6:20pm*** ...bingo... instability and the batteries are below usuable voltage on transmit. In fact, I was in mid qso w/ Dan N0TK when he tells me I'm 'chirping'...I double checked the voltage drop on transmit, & sure enough I'm toast. I switched to the K2 and completed the qso. OK, so what does this test tell me? It tells me 10 cells are better in THIS test, which is NOT REALLY indicative of the way I would operate my radio on batteries in the field! Also, I kept the output at 3.5w for both 8 and 10 cells, a smidge high for 8 cells (for max efficiency). On the other hand, it's awfully hard not to see that the 10 cells went a LOT further (3 hours) in this limited test. Maybe at 2w instead of 3.5w, the 8 cells would have lasted another 3 hours? Variables abound, apples vs oranges, too...however, in both tests my evening operating habits were nearly identical. It was quite obvious to me, my evening operating was cut short with the 8 cells. I was just getting underway when the bottom dropped out, so to speak. Maybe if the transmit drain was more 'evenly' expended throughout the day, the difference would not have been so great. I'll leave that one up to the experts. In the meantime, I'm charging my new 1800mAh cells as we speak ;) 73 John K7FD Notes: (K1 keydown voltage readings throughout the day) Time Keydown V (10 cell) Keydown V (8 cell) 7:00am 12.6 9.9 12 noon 11.9 9.4 5:00pm 11.7 9.2 6:00pm 11.3 9.0 6:20pm - 8.2-7.5... 7:00pm 11.1 8:00pm 10.8 9:00pm 8.8 9:20pm 8.2-7.5... PS. One unrelated HUMOROUS OT note. Last night I qso'ed Steve WD9FJL...and mentioned I was going to the DX convention in Seattle. Then he came back and said he was going to the DQ convention in Nashville. ? I thought he made a sending error...but no, he's the Dairy Queen rep for New Mexico! ++++++++++++++++++++++++++ Date: Thu, 19 Jul 2001 22:56:55 -0700 From: "N7SG K7FD" Subject: [Elecraft] KBT1: Energizer Bunny? OK, this is IT for now...last K1 battery news for awhile, I promise...BUT... ...I ran ten new **1800mAh** GP batteries all day starting at 7am...and here it is almost 11pm. This was the very first charge on the new 1800mAh cells so I'm hopeful they'll be even better after a few more cycles. Again, the K1 was turned ON at 7am, receive only all day, then 3.5w tx began at approx 5:30pm and throughout the evening until now. My last qso was at 10:49pm with HA3FTA. Keydown voltage still read 9.2v when I signed with Feri in Hungary (got a 559!). I would venture to say I 'put the peddle to the metal' tonight and kept the transmitter going hot n' heavy, either CQ'ing or calling foxes (thanks Jim and Doc!). Other highlights included a nice ragchew w/ 92 yr old YL Carmen WR6C, Todd AG0T and his 300mw, Tom N2UI with his FT817, and Lou W7DZN running an '8 cell' KBT1. Total qso's: 14, including the two foxii. In other words, I didn't baby the K1/KBT1 in an effort to 'stretch' the battery life...just my 'normal' operating. 7am to 11pm on one charge...16 hours, I'm happy! Now I gotta finish packin' for Seattle and the DX Convention tomorrow...I'm throwing the 1800mAh cells back on the fire right now to get them ready for the trip...please keep an ear out for K7FD/P & the K1/PW-1 this weekend, starting tomorrow evening I hope! 73, John K7FD Here's the hourly keydown voltage readings: 7am 13.0v 12noon 12.0 5pm 11.9 6pm 11.7 7pm 11.6 8pm 11.4 9pm 11.2 10pm 11.0 10:30pm 10.5 10:50pm 9.2 11:00pm bedtime! +++++++++++++++++++++++ Date: Tue, 24 Jul 2001 06:28:10 -0700 From: lhlousek Subject: !Re: [Elecraft] K1 Mojo Go Juice Hi Doc, <<>> I got my GP1800 batteries at http://www.greenbatteries.com/ along with their PowerHaus charger. Most chargers take at least two hours to charge 4 batteries and some take as much as 12hrs but the Powerhaus does it in 1 ~ 1.5 hrs or so. The charger is a reasonable size but it does have a separate wall wart. Another feature of the Powerhaus is that it will charge just two cells so if you are a turbo mod user you can charge the two extra cells. The charger and 8 cells cost $60 including shipping. That'd buy a lot of AA alkalines at Costco! A set of alkalines will run about as long as a freshly charged set of NiMHs, maybe a little less. The charger is larger and weighs more than 16 AA cells so depending on what kind of battery ops you intend to do alkalines may not be a bad solution. Radio Shack sells 1600mAh NiMH batteries and chargers as do most big consumer electronics stores that carry digital cameras. Make sure to check how long it takes for the charger to do the job. Remember, you gotta charge 2 sets of 4 batteries to fill up the K1. Elecraft has warned that some high capacity cells are physically too large to fit in the K1's battery holder. The GP1800 and Radio Shack 1600s fit properly. Lou W7DZN ++++++++++++++++++++++++++++++++