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LK-450NT
Hi all, Tomorrow I'm going to see a friend?that has some kind of problem with his LK-450 NT amp. At this time I have no idea what the problem is due to inconsistent?information. But I have a question, I've never worked on one of these but I'm assuming the network is very broad banded and you only adjust a "fine tune" for your operating frequency. My common sense tells me that inside there must be some kind of "broader" (lack of a better term) adjustment inside to get the network in the ballpark so a fine tune can dial it in. I'm thinking that especially on 160 and 80/75 it would be critical to get it close for either the top of the bands or the bottom of the bands. Am I on the right track? Also, is there any known common problems I should?be aware of? Thanks all. Bob? W4JFA |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育Yeah, Chuck – that must have sucked ! From around 2500W PEP out down to 1500W PEP out. Ouch ! ? But, as you say, not a big deal to any of us. ? From: [email protected] <[email protected]> On Behalf Of Chuck Neal
Sent: Friday, March 22, 2024 6:04 AM To: [email protected] Subject: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L network (Alpha 78) ? Well, there you go….250W AM carrier for 100% modulation. ? An Upgrade for you guys but when they did that with the 1500W PEP for us USA AM guys years ago, it was about a 3 dB hit.? Not that anyone observes it….{:>) ? -Chuck ? From: [email protected] [mailto:[email protected]] On Behalf Of michaeljcburns via groups.io ?
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
? ?Good day Chuck and Group., ? ?You were well stitched up, it means the FCC and ARRL thought a 4-1000, 100% plate modulated with all the trimmings was equivalent to a TL922 or SB220, amazing !! Our increase is from 400 pep at the aerial to 1Kw at the aerial, which allows the Guys to use what they've got legally.?You'll probably notice that if "G" stations adhere to it then you'll think "Why are the "Gs" an S point down HI . 73 de Michael G3TCA., =================== |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
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On 22 Mar 2024, at 05:26, michaeljcburns via groups.io <michaeljcburns@...> wrote:
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育Well, there you go….250W AM carrier for 100% modulation. ? An Upgrade for you guys but when they did that with the 1500W PEP for us USA AM guys years ago, it was about a 3 dB hit.? Not that anyone observes it….{:>) ? -Chuck ? From: [email protected] [mailto:[email protected]] On Behalf Of michaeljcburns via groups.io ?
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育Understood. Wouldn’t that be wonderful ? A licence-approved 4kW PEP !! Can’t see that ever happening……officially. ? Luckily, it happens all the time, unofficially. Especially on this reflector ! ? I’ll let you know how my YC156 amp goes when it’s completed…. ? Best 73…..and good luck with the regulators. ? John VK6JX ? P.S We tried and failed to get 1kW PEP here in VK. What they don’t know won’t hurt them. ? From: [email protected] <[email protected]> On Behalf Of michaeljcburns via groups.io
Sent: Sunday, March 17, 2024 7:15 PM To: [email protected] Subject: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L network (Alpha 78) ?
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
? Good day John and Group., ? ?We've only heard the figure 1 Kw banded about at the moment, got to wait for the details in writing on our new licences. When I made the post I had my tongue very deeply pressed into my cheek wondering if anyone gave us a chance with 1 Kw fully modulated. That would be something, we'd all be ordering one of Jim's 3CX6000 amps HI. Best of luck with getting the Kw. 73 de Michael G3TCA., ================== |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育Hi Michael. ? 150W DC fully modulated = 400W PEP. So, I imagine your new granted level would be 1kW PEP….? ? This is the new power level we were asking for down here in VK. Our existing legal power output level is also 400W PEP. ? Cheers, ? John ? ? From: [email protected] <[email protected]> On Behalf Of michaeljcburns via groups.io
Sent: Saturday, March 16, 2024 10:56 PM To: [email protected] Subject: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L network (Alpha 78) ?
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
? Good day Jim and Group. ? I reckon your suggestion of using a Pi-net on it's own is the best way to go, can always up the Q a bit and see what happens. ? That line 74 where GM3SEK uses that formula for arriving at the intermediate Rm just gives an equal conversion ratio from plate load to Rm and then Rm to Rout ie 50 ohms which as you've found with your calculations, a greater amount is needed from RL to Rm. ? I make that value in line 74 as 200 and then make line 75 , the Q of the L network as 2. In the example he uses at 29.7 megs, if you look in the Pi-network calculation of the Pi-L network part of the calculation the actual value of C1 is 1 pF !!!!!!!!!!!!!? I remember the whole point of using a Pi-L was so we could have a bit more leeway on the value of C1 on 10 metres so there was some actual adjustment available. ? Suspect these Pi-L-L-L..... networks were more intended for the folks using half a megawatt +++ at Droitwich and their like. I got into this Pi-L stuff in the '60's when a W6 (perhaps R Rinaudo) was publishing circuits using the Pi-L, seemed like a good idea at the time as our BBC band 1 405 line TV was located between 42 and 65 megs. you can imagine the opportunities for wiping out the neighbourhood's TV? HI. ? We even had companies manufacturing TVs with an IF of 14 megs (amazing). ? We've had our power level upped from 150 watts DC fully modulated , to wait for it ,1KW. Do you think it will be 1KW fully modulated or just 1KW pep. We're waiting to be informed. ? When I see the amount of output you put on this group I visualize you've got half a dozen young ladies taking copy while your perambulating the office annunciating your postulations. ?73 de Michael G3TCA., =================== |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
On the gm3sek software, it does a calc, to arrive at image Z...called 'RM'.? ( sq root of? R1 X R2).? R1 = transformed plate load Z? ?R2= 50 ohm output Z).? Fact is,,,? u can enter any value u want on line? 74.? ? Myself, I avoid the PI-L like the plague.? ?And in this case, a lower Q? with the PI-L doesn't work due to the tube C.? ? Back between? 1979 and 1989, when I was up north, 2 of us would visit the VE7ZZZ contest station.? ?It was operated MM? in phone contests...and MS in CW contests.? ?No filters, band pass filters, LP filters, nor stubs used any where.? ? BUT the ants were far apart ( 150-200')? from each other.? ?Separate tower and yagi for? 40-20-15-10m.? ?160m was a vertical wire in a tree.? ?80m was an extended zep between 2 other trees...and up 90'.?? ? Perhaps if multiple ants on the same tower, then the issue starts up.? |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
Good day Jim and Group. ? Excellent effort as always Jim.? In the dim and distant past before spreadsheets we used to make Peter's (GM3SEK's) Rm as 200 ohms and the Q of the eL coil as 2. As you've noticed all that stray capacitance around the tube sets the minimum Q for the Pi part of the circuit. I've got all the formulae written on a crib sheet. makes working out easier. 73 de Michael G3TCA., ================== |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育Thank you, Jim. I’ve had to reverse engineer other people’s results in the past to find out that we were actually talking about the same thing. I have learned one thing in my 40+ years as a professional Electrical Engineer – nomenclature is king. And, everybody needs to be on the same page. Avoids a lot of meaningless arguments. ? Respect, for all that work. ? John VK6JX ? From: [email protected] <[email protected]> On Behalf Of Jim VE7RF
Sent: Tuesday, March 12, 2024 12:15 PM To: [email protected] Subject: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L network (Alpha 78) ? Finally got it all figured out.? It's a bit of a complicated mess.? There is a total of 5 different? 'Q's'? involved on the GM3SEK? PI-L spreadsheet.? ? The short of it is.... I had to maladjust the 'total network Q' (line 39) to '7.74' ......so that the 'PI network Q'? (line 82, called? 'Q0PI' ) = 6.0? ? The 'PI network Q'? ? is what Peters is using to enter his Q of 6.? This is the PI-net portion of the PI-L.? On the GM3SEK sheet, only line 38 can be changed.? It spits out everything else.? INPUT Q? ? =? 4.4? ( Line 83)? ( called Q1) Input Q + Output Q =? PI network Q.? (4.4 + 1.6 = 6.0)? ?( PI network Q on Line 82) The L NETWORK? Q? = 1.7? ?(line 75) ( called QL) OVERALL NETWORK Q? ( called? Q0) =? ?PI network Q + L network Q ( 6.0 + 1.7 = 7.7)? I also used Peters 200 ohm image Z, and 1100 ohm plate load Z.? ?Then the main coil? comes out to peter's 29.0 uh.? ? I did have to maladjust the plate choke to 141.5 uh? to get the main C1 tune cap = to peter's? 350 pf.? ( the plate choke value has a big impact on the C1 cap...as the 2 are in parallel electrically.? Software spits out 1487.2 pf for the C2 cap.? ( close to peters 1500 pf) Software spits out 7.66 uh? ( close to peters 7.65 uh)? ? Short of it is I'm entering...? 'overall network Q'... ..while peter is entering .... ' the PI net Q'? ? BTW, coil current in the main coil is? INPUT Q x dc plate current.... and not PI net Q? x DC plate current.? ? (I verified this via actual measurement).? 4.4 x 2.75 dc amps? = 12.1 RF amps in the main coil.? ? ?Same deal with the simple PI network ( INPUT Q x DC plate current = coil current.) So it's semantic at best.? On 40m, min OVERALL NETWORK? Q that can be used with a PI-L? is? 8 ...........? ?(This is all based on having the MIN C1 being at least 14 pf).? ? The lower Q concept works on 160+80m...... but not 40-10m.? The Tube C is just too great.? ? |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
Finally got it all figured out.? It's a bit of a complicated mess.? There is a total of 5 different? 'Q's'? involved on the GM3SEK? PI-L spreadsheet.? ? The short of it is.... I had to maladjust the 'total network Q' (line 39) to '7.74' ......so that the 'PI network Q'? (line 82, called? 'Q0PI' ) = 6.0? ? The 'PI network Q'? ? is what Peters is using to enter his Q of 6.? This is the PI-net portion of the PI-L.? On the GM3SEK sheet, only line 38 can be changed.? It spits out everything else.? INPUT Q? ? =? 4.4? ( Line 83)? ( called Q1) Input Q + Output Q =? PI network Q.? (4.4 + 1.6 = 6.0)? ?( PI network Q on Line 82) The L NETWORK? Q? = 1.7? ?(line 75) ( called QL) OVERALL NETWORK Q? ( called? Q0) =? ?PI network Q + L network Q ( 6.0 + 1.7 = 7.7)? I also used Peters 200 ohm image Z, and 1100 ohm plate load Z.? ?Then the main coil? comes out to peter's 29.0 uh.? ? I did have to maladjust the plate choke to 141.5 uh? to get the main C1 tune cap = to peter's? 350 pf.? ( the plate choke value has a big impact on the C1 cap...as the 2 are in parallel electrically.? Software spits out 1487.2 pf for the C2 cap.? ( close to peters 1500 pf) Software spits out 7.66 uh? ( close to peters 7.65 uh)? ? Short of it is I'm entering...? 'overall network Q'... ..while peter is entering .... ' the PI net Q'? ? BTW, coil current in the main coil is? INPUT Q x dc plate current.... and not PI net Q? x DC plate current.? ? (I verified this via actual measurement).? 4.4 x 2.75 dc amps? = 12.1 RF amps in the main coil.? ? ?Same deal with the simple PI network ( INPUT Q x DC plate current = coil current.) So it's semantic at best.? On 40m, min OVERALL NETWORK? Q that can be used with a PI-L? is? 8 ...........? ?(This is all based on having the MIN C1 being at least 14 pf).? ? The lower Q concept works on 160+80m...... but not 40-10m.? The Tube C is just too great.? ? |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
开云体育He didn’t, Mike. He said “playing dumb”. Not the same thing at all ! Good to see passion is not dead around amplifiers. On 11 Mar 2024, at 21:27, mike repinski via groups.io <mikflathead@...> wrote:
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Re: Kudos to Digi Key and Hammond Mfg.
开云体育If it's shipped freight, it likely is dropshipped directly from
the factory (Hammond). Mine was. Steve, K0XP
On 3/11/2024 3:16 PM, Alan - W5ARM
wrote:
On Mon, Mar 4, 2024 at 08:23 AM, NI5L wrote: --
See my QRZ.com page at |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
We really don't need people being called dumb.
On Sunday, March 10, 2024 at 08:25:18 PM EDT, Amp Guy Llc <kb1sel@...> wrote:
Keep playing dumb Correction (calculations)auto correct On 2024-03-10 18:20, Peter Voelpel wrote: > Whats your problem? > I don?t know what you mean with Carla. > > This thread is about Pi-L networks, not about anything you do. > > 73 > > -----Original-Nachricht----- > Betreff: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L > network (Alpha 78) > Datum: 2024-03-10T23:31:48+0100 > Von: "Amp Guy Llc" <kb1sel@...> > An: "[email protected]" <[email protected]> > > The site jim uses provided the input and output network Carla’s for the > 3x6 10kw pa and were? dead nuts on. > > Has also been used for more pa’s then I can count in the past. > > Peter I’m starting to think you’re the kinda guy that just won’t admit > they are wrong. > > Seems like you are going out of your way to put down how we have > decided > to build this current pa. > > I already own 98 percent of the parts I’m using including the re > purposed cabinet. I’m fitting components of ample rating to support 100 > percent duty cycle with minimal cost out of pocket. > > 73 > > > > > > > On 2024-03-10 12:38, Peter Voelpel wrote: >> Hi Jim, >> >> I use the formulas by Eimac and also the PIEL software depending on >> what computer I use. >> >> My values for the anode capacitors are the total values. >> >> Any strays and tube capacitance etc. as well as inductor lead length >> are not taken into account. >> >> I guess you deducted capacitances like that of the tube from your >> figures. >> >> The current through the coil of the pi part is indeed Q*Ia where you >> used 3.2 and not 6. >> >> With a Q of 6 the current is 6*.2.75A= 16.5A. >> >> You also used different frequencies, I used 1.8 and 7MHz but that will >> not change much. >> >> I am operator at the M/M contest station DR1A so familiar with >> fighting harmonics. >> >> But how many stubs will you connect to a multiband amplifier? >> >> A single stub will kill some harmonics but not sufficient enough, we >> use cacaded stubs made from LDF cable behind the mono band amplifiers. >> >> >> I measured a YC-179 bolted to the chassis. >> >> 73 >> >> Peter >> >>? And this is copper after >40 years: >> >> -----Original-Nachricht----- >> >> Betreff: Re: [ham-amplifiers] High Temperature in Toroid of the PI-L >> network (Alpha 78) >> >> Datum: 2024-03-10T16:29:32+0100 >> >> Von: "Jim VE7RF" <jim.thom@...> >> >> An: "[email protected]" <[email protected]> >> >> On Sat, Mar 9, 2024 at 10:46 PM, Peter Voelpel wrote: >> >>> Sorry Jim, >>> >>> I can?t follow your calculations and for what reason a Q of <8 >>> should not be possible on 40m. >>> >>> Lets assume a YC179 with 6kV on the anode and 2.75A anode current. >>> >>> Tube output impedance will be 1.1kOhm at 10kW. >>> >>> Pi-L intermediate impedance 200 ohms. >>> >>> Coil currents will be about 15A. >>> >>> Example for 160 and 40m at a Q of 6. >>> >>> 160m: >>> >>> Ca 350pf, La 29?H, Cb 1500pf, Lb 7.65?H >>> >>> 40m: >>> >>> Ca 90pf, La 7.5?H, Cb 380pf, Lb 1.97?H >>> >>> 3CX6000A7 has 12pf less output capacitance, at 6kV output impedance >>> will be lower then 1.1kOhm as current will be higher and therefore >>> La smaller , I guess a Q of 6 will be possible even on 20m with a >>> Pi-L. >>> >>> The whole tube family does not need a harmonic suppressor. >>> >>> Harmonics of SSB signals can be copied. Once I did the CQ 160m >>> contest and were phoned by a ham 120km away, he found my signal in >>> the 80m dx window. >>> >>> Copper / copper tubing is very expensive nowadays here and silver >>> plating does nothing on HF. >>> >>> I get more then 7 Euros for 1kg scrap copper like LDF cable >>> leftovers. >>> >>> 73 >>> >>> Peter >> >> ##? I just? plugged ur? YC-179 numbers into the GM3SEK PI-L software. >>? The YC-179 has 35 pf anode to grid C... which rises to 52 pf with >> grid flange bolted to chassis. I also allowed for an extra 5 pf of >> stray C on top of the 52 pf..( so a total of 57 pf used).? ? I also >> used ur 6 kv loaded @ 2.75 amps...and also used? your? 200 ohm image >> Z....and also ur? 61% eff, and used 1840 khz for the design freq. >> And also used a 400 uh plate choke.? And also used ur 1100 ohm plate >> load Z....and also ur 10 kw output. >> >> ##? This is what it spits out...for a total network Q of 6.? ( Input Q >> = 3.2? Output? Q = 1.0? L network Q =? 1.7 )? Coil current in L1 >> should be input Q X plate current or 3.2 x 2.75 =? 8.8 amps. >> C1- 215.7 pf >> L1 - 35.53 uh >> C2 - 1198.2 pf >> L2-? 7.49 uh >> >> The above is not even close to ur calcs.? ( Ca 350pf, La 29?H, Cb >> 1500pf, Lb 7.65?H )? What are u using for software ??? >> >> ............................................................................................................................................................................................................................................................................................................................................................................................. >> >> >> Ok, let's try 40m (7150 khz)? and again using your numbers. >> C1-? 9.6 pf >> L1 -? 9.14 uh >> C2 -? 308.3 pf >> L2 -? 1.93 uh >> >> Again, not even close to your numbers.? ? ( Ca 90pf, La 7.5?H, Cb >> 380pf, Lb 1.97?H? )? What are u using for making ur calcs ?????? >> >> A 1/4 wave shorted stub will kill all the even harmonics.... by 15-23 >> db.? Try listening to urself on a 2nd RX on the 2nd, 3rd, 4th >> harmonics..... while Tx'ing on SSB.? Say TX on LSB / USB on 7100, then >> listen on 14.200 and 21.300 and 28.400 mhz. >> >> Flexible Copper tubing has risen a bit in price, but is still >> relatively cheap.? Typ comes in 10'- 15' - 25'- 50' rolls.? And in >> 1/8"? to? 1.125" OD sizes....and every size in between. >> >> I hate the look of bare copper,? which really looks bad after several >> years.? The silver plating is cheap, and is strictly an aesthetic >> thing.? ? >> >> >> Links: >> ------ >> [1] /g/ham-amplifiers/message/40324 >> [2] /mt/104698543/8135091 >> [3] /g/ham-amplifiers/post >> [4] /g/ham-amplifiers/editsub/8135091 >> [5] >> /g/ham-amplifiers/leave/12941173/8135091/773995006/xyzzy > > > > > > ? > > > |
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Re: High Temperature in Toroid of the PI-L network (Alpha 78)
Keep playing dumb
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Correction (calculations)auto correct On 2024-03-10 18:20, Peter Voelpel wrote:
Whats your problem? |
Bob
Dave, KW4M
Alan - W5ARM