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I have a AL80B with a factory installed QSK-5 board. (new 2019) The amp xmit fine. Receive is down. Typically it's those stupid fuse lamps Lp1, Lp2.... Open cover, remove Lp1/Lp2 -- install new ones. Turn on AMP no problem, receiving fine. Turn STBY /XMT OPR on.. poof, lamps blow out. Try with nothing connected to amp, no control lines, nothing. Replace L1/L2, turn on amp, fine. Flip up XMT OPR , lamps blow out. Amp now has low receive, and plenty of output, receive is down -20 -30db . . All bands. Anyone seen anything like this?l've replaced these lamps 1x in 5 years, and it was a no brainer. Something in the receive chain? Pin diodes? ARGH.. Glenn

Here the plate block cap assy is installed. 5 x 200pf @ 15 kv rated doorknob caps are used to make up the assy. The 200 pf cap's were chosen since they are rated at 15 amps CCS of RF current on any freq > 5.11 mhz. Total max current rating is now 75 amps. Total capacitance is 1000 pf. (The 200 pf HT-57 cap is the....'go to'.... cap for the HT-57 series since their 200 pf cap has the highest current rating of the entire HT-57 series). Similarly for the bigger HT-59 series, the ...'go to cap'.....in a HT-59 is their 250 pf cap, rated at 35.5 amps CCS on any freq > 16.0 mhz). 1000 pf = 88 ohms of XC @ 1.8 mhz The general rule for plate block cap total value is.... The XC of the plate block cap assy shouldn't be any more than 5% of the plate load Z...at the lowest freq used (1.8 mhz in this case). In this case, with 7 kv loaded B+ @ 2.5 amps, the plate load Z = 1555 ohms. 5% of 1555 ohms = 78 ohms. 1200 pf would have been 73 ohms of XC.... but in this case, there is severe space restraints, and only 5 x caps can be used. Close enough for this application. 2 x copper straps used, one above, and one below..... with the input at the tube end on top.... and the output at the opposite end...on the bottom. Done this way so the total physical, combined distance in + out, stays the same for each cap. Done this way, the RF current is equally divided between the 5 x caps. (Another similar method used, when 6 or 8 caps are used, is 2 rows of 3 caps.... or 2 rows of 4 x caps. In those cases, the input is dead center between 2 x caps at left side of the top plate...and output is dead center between last 2 x caps, at right side of bottom plate. Same deal, the current will divide equally between the caps). HEC (high energy Corp) sez the PEAK RF voltage ACROSS the cap (or paralleled cap assy).....PLUS any ...'DC bias' can not exceed the stamped cap's voltage rating. What HEC calls ...'DC bias', we call B+. The saving grace at the low freq end (160m) is.... there is hardly any RF current flowing through the plate block cap asy.....and the peak RF voltage is very little. At the upper end of the HF spectrum, 10m, there is a LOT of RF current flowing through the block cap assy. Reason is..... the anode to grid C on the tube makes up 90% of the total required C1 tune C. Think of it as the tube C is 90% of the required C....and the actual C1 tune cap is a tiny, variable padder. Issue is.... the plate block cap resides between the anode and the C1 tune cap. All that current that flows through the tube C now also has to pass through the block cap assy. The XC of a 1000 pf cap on 29 mhz = 5.5 ohms. So even with high current flowing through the block cap, the peak RF voltage is still miniscule. Just to recap, enough C is required for the lowest freq....and the cap has to be able to handle a lot of current on upper HF. https://www.youtube.com/watch?v=bMmCXeB_cew

12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 17 Here the grid and plate overcurrent protection, plus grid current and plate current metering are being done, using existing boards, with some component values modified for this application. The idea here is to be able to re-use the existing metering (100 ua meter movements), and re-scale them to what's required in the new amplifier. Existing metering (and mating overcurrent boards) was for another amplifier, which used lower value scales. Scott has several of these boards, all functional, so it was decided to re-use em for this application. https://www.youtube.com/watch?v=0LaIcnQBuTo

I have an Ameritron 811H and a Dentron Clipperton L amplifier that I was driving with a Yaesu FTdx3000 through the Ameritron ARB-704 interface (only one in the circuit at a time) . I am using the plug and play cable between the 3000 and either amp. Now neither amp seems to key. With the amp in standby all seems well and I am able to communicate as normal. It would appear that the relay on either amp does not closes. I.E., when I PTT on the transmitter I get the 3000 transmit LED as well as the LED on the 704 but nothing on either amp. I was planning to try to read out the voltages coming out of the linear out connection on the 3000 for a starter. Being both amps are acting the same I am thinking that the problem is with the 3000. Lastly, I will not totally rule out operator error. Any and all advice On what I should check or how I should proceed is appreciated. Attached is a pictorial of my set up. Post note: don’t know if this is relevant but rereading the 704 manual it states that 13.8 volts is coming from the transceiver through the plug and play cable. As a result no external power to the ARB-704 is necessary. In addition to the plug and play cable I have had a 12V wall wart feeding the ARB-704. Fortunately, I didn’t see any ill effects before this point. Thank you. 73 Harrison N1FAM

It's still in a transitional phase as of today. A lot of items are being shipped from OH to CT. A lot of new items will be added, including the entire Penta tube lineup, for both amateur and commercial users. https://www.youtube.com/watch?v=eGAnM8Tboms

Hi, FYI new email below: Philw9ixx@... 73, Phil W9IXX

12 KW CCS ON 160-15M....USING THE 3CX-6000A7..... PART 16 Here all the various tank coil taps are completed. Adjustable SS spark gap installed across the vac load cap. After this video was done, the 2nd adjustable SS spark gap was installed across the vac tune cap. Spark gap across the load cap protects the load cap. Spark gap across the vac tune cap protects the vac tune cap AND the bandswitch. There is also a.... '.7 uh pre-coil'...... that is wired between output of plate block cap assy....and the hot side of the C1 vac tune cap. The anode to grid C + stray C (lower anode fins to chassis) and this .7 uh pre-coil form the step down L network. This transforms the 1600 ohm plate load Z (7200 vdc loaded @ 2.5 amps) down to just 361 ohms @ 21.225 mhz. Then a lower, loaded tank Q can be used for the PI network on 15m. That L network also has a lesser effect on all lower bands. IE: 939 ohms @ 14.175 mhz. 1419 ohms @ 7.150 mhz etc, etc. The original target value for the pre-coil was .6 uh. (which would have transformed the plate load Z down to just 483 ohms @ 21.225 mhz). Trying to tap a tubing coil is tough enough as it gets. With the temp 1600 ohm resistor from anode to chassis....and analyzer on output side (and the pair of RJ2B's relays externally powered on), the swr was 1:1 after tweaking the tune + load to the calculated values for each band = jives with the spreadsheet / GM3SEK software. Previously, both the vac tune + load caps were mapped out, with pf vs turns counters....and a cheat sheet made up. On a similar note, once the tune + load caps tweaked for 1:1 swr, the caps are left alone....and the upper / lower freqs for the 2:1 swr points are noted down. 160 khz wide on 160m, 310 khz on 80m, 600 khz on 40m, 800 khz on 20m, and 1 mhz on 15m. So far, so good. All measurements for the adjustment of the tune + load caps were done with the top lid on. All playlists. https://www.youtube.com/@amprepairguy/playlists

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

Any of these bigger metal tube amplifiers can be used for: (A) ISM (B) educational (C) testing DL's. (D) CAP (E) MARS (F) plasma (G) sputtering (H) tube testing (I) deep tissue healing (J) diathermy (k) low latency, high speed stock market transactions (L) SW broadcast (M) marine Superbowl 6 (O) Embassy (P) CQ WW (Q) Etching (R) emergency use (S) military (T) irradiation. Ok, here's the deal. Next time some bozo asks.....'where is this amp legal'....and 'why so much power' they can look at the above list....and pick one or more at random.

HERE THE FRONT PANEL IS DONE..AND PAINTED. THE 2 LOWER TURNS COUNTERS EACH DRIVE A 6:1 VERNIER...WHICH DRIVE THE C1+C2 PI TUNED INPUT CAPS. THAT MEANS 0-300 INCREMENTS TO GET FROM MESHED TO UNMESHED. https://www.youtube.com/watch?app=desktop&v=9ZCBgp1-Kaw

Does anyone know where a replacement relay can be obtained? Or the manufacturer's name and part number? Thank you.

Here the complex chain drive is finalized. Spur gears used on the inside of the inner front panel. The idea of the 3 x chains is to get the tune + load turns counters, and the bandswitch knob located in the correct positions on the outer panel. After some preliminary attempts, this latest version works good...and the front panel simply sides off....leaving all 3 x chains intact. On a side note, I shipped the new 397 uh plate choke today, along with a pair of .01uf @ 30 kv disc caps, used for bypassing at the cold end of the plate choke....used for the lower bands. A pair of 500 pf doorknobs will also be used at cold end of same plate choke...for bypassing at the upper bands. A pair of 100 amp supercon panel jacks also shipped. It's slowly coming together. This chain drive setup complicates things quite a bit, and required a lot of head scratching. But it's finally done...and works. The mapping has yet to be done (turns counter markings vs actual pf) for the tune + load caps. Once done, the mapping....aka .....'cheat sheets' can be made up. https://www.youtube.com/watch?v=Q3zf2PrzJs0

Howdy Folks, A quick question (and maybe a stupid question... but): Can anyone see any issues in reversing the polarity on the key-line circuit (from "positive ground" to "negative ground") on the FL-2100B amp? Has anybody attempted this? Background: I'm refurbishing an FL-2100B, and have already done some upgrades and mods: New PS diodes, cap's & boards (from Harbach); Directly-grounded the grids; Performed the "Self-bias mod" (CT of filament xfmr grounded thru a 100k resistor on RX, grounded on TX thru a separate/new cube relay); Installed a new band switch (original was burned on 80m capacitor contacts), and some other general clean-up. Currently, the key line is "positive ground" (utilizing a simple, single-diode 1/2-wave rectifier and 1000uF cap). The positive side of this DC circuit goes to the chassis ("ground"), and negative side to the keying relay. Thus, when the RCA jack is shorted to "ground" by a transceiver, it is actually switching the "positive" side. I have read elsewhere that this "reversed" polarity could cause issues with some "modern" transceivers which require a "negative ground" key-line circuit (particularly those employing solid state/transistor switching), and therfore requiring the use of an external key-line "buffer" (which I have built and used succesfully). Anyway, since the bias-circuit no longer has anything to do with the keying relay circuit, any issues that anyone might be aware of, by reversing the polarity? I've studied the circuit schematic (and corrected it, as per my other changes), and I can't see anything that would prevent this from working. Since doing that bias mod, the key-line power supply only supplies power the key-line relay, and has nothing to do with bias. The key circuit currently runs at 19 volts (open circuit) and 280 mA keyed. Ultimately, this amp will be put up for sale, but I wanted to do the upgrades & mod's before I put it up for sale. Following the aforementioned modifications, I have run it, driving it with my Yaesu 101D (using my key-line buffer), and it works quite well, giving about 650-700 watts PEP (on a Telepost LP-100A). Of course... I wouldn't run it that hard in regular service, but it did work fine for the short testing done. The newer "Taylor" 572B's are in great shape. Lastly, I'm quite well aware of the many other quirks and issues with the FL-2100's, so no need to get into a discussion about all of their other problems... LOL! Thanks for the help. -- 73, ~Alan

Here, some updates. This is the beginnings of the elaborate chain drive assy. 2 x more chains, yet to be installed, plus tensioner's....( for the vac tune + load caps). Note on the big model 90 switch, there is a tall, rhombus shaped black end plate....at both ends of the switch assy....(oriented vertically). In the normal configuration, the black end plate, at the FRONT of the switch is mounted on the INSIDE of the panel (along with the spring detent / nylon assy). In normal configuration, only the 1/4" steel shaft sticks out the front of the panel....through a panel bearing. In this amplifier, the switch was taken apart, and the FRONT end plate was mounted on the OUTSIDE of the front (inner) panel....( along with the spring detent assy). Done like this so the switch wafer assy doesn't stick as far back on the inside of the RF deck. There is severe space constraints on the inside of the RF deck. Ferrite loaded plate choke finally fabricated...(and tweaked)....and tested on the VNA. It will be shipped out to Scott later this week. I had to make new, narrower copper straps ( 1/2" vs 3/4") so I could get an extra 8 turns onto the assy. The winding is now 5.5" long (vs 5.0") . Final choke config is now 405 uh. This dropped the 1st series resonance freq down to where I want it. (1st series resonance now at 17. 125 mhz...midway between top of 20m..and bottom of 15m..so choke won't work on 17m). The amp only works on 160-80-40-20-15m. NO 17/12/10m on this amp. It only has a 5 position bandswitch...with 4 x sequential rotors.... to make it into a shorting style bandswitch. And no, we can't re-use the 15M tap on 17m. Reason is, with the L coil inserted between the plate block cap assy, and the C1 vac tune cap, it's designed to lower the loaded tank on 15M. In software, if 15m tap re-used on 17m, the loaded tank Q skyrockets to an unacceptable value. Without the extra '"L" coil installed, the Q is too high on 15M..... BUT if re-used on 17M, would only increase the tank Q by another 17%. So L coil installed, low Q on 15m, and no 17m operation. Since no 17m operation, having the plate choke resonate near 17m band is a non issue. The model 90 switch is a 10 position, 36 deg switch. The max you can do with that switch is a 5 pole sequential rotor...which results in a 6 position bandswitch. Scott is re-using an old model 90 switch, and it only came with a 4 pole sequential rotor...so only 5 x bands. Original loaded plate choke with it's 5" winding, was 305 uh, and resonated at 19.750 mhz....(and also 33 mhz). Interestingly enough, as an experiment, I removed 3/4" of turns so 12.5 turns removed...and winding was now only 4.25" long. Inductance dropped to 249 uh....and 1st series resonance shifted up to 23.3 mhz.... ( and 2nd series resonance shifted up to 39.990 mhz). Ok, winding completely removed....and new, narrower straps installed. This time, winding length increased to 5.5". Choke is now 405 uh. 1st series resonance is now 17.125 mhz.... ( and 2nd series resonance is now 29 mhz). I believe this latest, and last config will work good. It will also minimize the residual RF current through the choke on 160m. Stay tuned for more. https://www.youtube.com/watch?v=exY4_UBmhsI

Even located in the adjacent room I can still hear an arc if were to occur. The 3x6 I’m building now will have a spark gap on the c1 and c2 , grid overload , plate overload , cathode return fuse , grid current fuse , plate b+ fuse , series glitch plate b+, fuse in series with one side of the plate secondary , blower pressure interlock. Should be pretty bullet proof.

Does anyone know if Ameritron have resolved the issues with their spare parts plate chokes? I would be interested in purchasing a couple if they are not going to burn up. 73, Alek VK6APK.

I recently acquired a few Alpha amplifiers that needed repair. Along the way I decided to test all 10 tubes I had on hand. I put each 3cx400A7 in one at a time, let the filament run for a while to burn in. I Applied 1500 volts for 10 minutes or so.. then Keyed up While monitoring Grid and Plate current for 5 minutes. I noted idle current and then applied 15w RTTY drive on 20 meters and noted output power. Out of the 10, Two where bad, one had open filament and the other a grid short. The other eight where all good. Output power for those eight tubes: 175 w 175 w 175 w 150 w 140 w 120 W 100 w 75 w I let them run each tube keyed for 5 minutes or so and power was stable, and no tuning would produce more. All tubes ended up at pretty much exactly the same tune and load. ONE of the new tubes made 50W but after a cycle of key OFF and Key ON power rose up. 75, then 100, then 120. It ended up at 175 over about a 10 to 15 minute period. Interesting to see it rise up like that. Something was coming back to life. ALL other tubes made power instantly. What is interesting is that even the tubes that have lower output power and gain at 15w, make FULL power in the amplifier. I can take the two weak tubes, 75 and 100, and put them in the amp and make 1500w out with a woodpecker. I can put the best three in the other map and make 1800w. I can remove them and put the weakest three in the amp and make 1800w. Is there a better way to test power tubes? Or do you really need to just test them to full output? I had reservations about applying 2700 volts to them right away, that's why I used 1500v and low drive. Some of the tubes where new and marked 1980 so some run time is probably advisable at low voltage. I guess the drive and or added B plus is overcoming the loss of gain? C