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Here's a simple request from one op who is interested in amps. Personal grudge matches are bad news and will put off people who don't have any ax to grind. If we really want to support ham amplifier work, this stuff is counterproductive. Let's take our flames back to the NNTP world. I am giving the Yahoo group a try, because I think the anonymous moderation and "appropriate use" policies of the other list were very worrisome. I hope I don't have to unsubscribe from both of these groups! 73 Martin AA6E

Just in case some of you don't already know http://groups.yahoo.com/group/rfamplifiers/

All, I have the following four pieces of test equipment for sale; (1) Model 1020-B Megohm Meter by Freed Transformer 1 meg to 100k meg (2) Model 404M3 "Hypot" by Associated Research 4 kV @ 100w (3) Model 3050 sine/square wave generator by B&K Instruments (4) Model 3500 5-1/2 digit DMM by Data Precision I bought these with some other equipment and was going to overhaul each. I've not had the chance to thoroughly test each, and already have other equipment like this, so I'm going to sell these cheap as a lot. The cost for the lot is $75 US Plus shipping. Postal money order prefered. Please e-mail me at: craxd1 at verizon.net Thanks, Will

I have obtained a Drake L7 amp from an estate. It had lightning damage to the power supply. I need to replace a couple capacitors and diodes. Has anyone rebuilt this supply? I read somewhere on the Net that a complete board can be purchased from a company in California but I lost the info. Any suggestions? Tom W8JWN

This may be my first and last post on this list, but I wanted to clear a few misconceptions: Tom Rausch is not the Admin of Amps. I'm not either ;^) W4AN was not a fan of free speech - he replaced me as Admin of Towertalk when I refused to censor posts there; this is not a knock on Bill, just a difference of philosophy. I run a local community affairs mailing list with only two rules - sign your real name and maintain basic civility - keep it substantive, not personal. In 6 years, I've had to ban one person for a week. A parallel list has no such rules, and has disintegrated into ugly name- calling. From what I have read, such a regime on amps would have worked pretty well, though the Admin would have had to ban a few people. 73, Pete Smith N4ZR

I'm searching for a solid state amplifier circuit, a Henry model C130A30 (for VHF FM). The one I have seems to have been modified, I see some resistors strangely connected both at base and collector; also after an extensive search (Google, Alltheweb, data sheet pages, and so) I did not yet found nearly a bare specification of the transistor used. Input is specified in the range of 20..40 Watts, and output of 130 Watts, and as I see it, the circuit consists of a resistive input attenuator, then follows a first stage with a CD-4778, which drives three CD-4778 (yes, the same) in parallel. All four are B-E open. It has a nice LPF at the output. Very good components with the exception of the above stated resistors. Thanks in advance Best regards Guillermo - LU8EYW.

Jim, Grid drive I suppose? In GG I would guess with 200W drive maybe 5-6 kW, or? Im planing to replace my 2x4-1000As with a YC-156, I think its a ideal tube. As soon as I can get hold of a good one at a decent price, would be a quick swap. However it will be GG. The 4-1000A is a pain in the rear end and Im getting to old to struggle with them. 73 Jim SM2EKM ----------------- pentalab wrote:

Gents On these 3CX-6000's and also the socketless version [ YC-243], I fool with from time to time, Eimac/ Svetlana state's the grid diss at 225 Watts CCS. [3CX-3000A7 is also 225 w CCS grid] Now, since the tube(s) can be operated in either GG OR grid driven.... it occured to me that in grid driven mode... the grid should still has a 225 w CCS rating ??? The point here is..... in GG service... you bolt this huge grid ring to the chassis.... and in the case of the socketless version.... an even bigger diam grid flange is bolted to the chassis ! Now... that alone should heatsink the grid ??? Since the grid is sitting in a vac... the only way for thermal heat to escape is via the grid flange. Since the below chassis compartment is pressurized... one might think the actual grid dissipation can perhaps be increased via this heatsink action ?? [GG mode] Am I out to lunch here ??? Later..... Jim VE7RF

Since Eimac never made a chimney for either a 3CX-3000A7 or a 3CX-6000A7 [or the socket] several after market chimneys have appeared. I purchased the one for the 6000A7. It was solid 1/4" thick teflon... straight up and down, no flanges.... and it's weight held it to the chassis. 6.130" ID 6.630" OD We found that this restricted the airflow up from the chassis too much. [both the ceramic 'stem' on the 3000/6000 are identical.. and much smaller diam than a YC-156 or a 10,000A7. ] For an experiment, I remember W7IUV had fabricated a fiberglass box around his YC-156.. for a chimney. We tried the same trick... except the vertical sidewalls were made from wood... about 9" square... top was also made from wood.... and the original chimney was placed in a groove.. on top of this wooden affair. Now we could increase the hole sizes on the chassis. The result was a huge improvement! Intead of the original 205 cfm... we are now getting an easy 320 cfm [using a Dayton 5C508 dual speed, capacitor start blower]. On the next chimney... we will toss the after market straight up and down chimney... and just increase the vertical sides of the box... and use a solid teflon top lid.. with a 6.130" hole in it. This technique can be used on any metal tube. The after market chimney's for the 3000A7 [4.130" ID] restrict the air too much as well. On one 3000A7 project... I used a SK- 306.. designed for a 4CX-5000A7.. which is a bit too big a diam at the top.... so we filled the gap.. by wrapping a few layers of silicone rubber around the tube.. held in place by a SS hose clamp... worked good. ... since the SK-306 chimney has a flared out base. Eimac specs the 6000A7 for 205 cfm of air. [based on a 50 deg C /121 deg F inlet air temp.] With 320+ cfm... and an inlet air temp of 25 deg C..... we calculated the anode diss is now an easy 8500+ Watts ! Talk about the sleeper of the year. This tube is real easy to increase it's stock anode dissipation. The secret is the small diam ceramic 'stem',makes for larger fins underneath... compared to a say 5000A7/YC-156..... which has a huge diam 'stem'... and a smaller anode cooler. The Dayton 5C508 blower is a dual speed 1100 rpm /1450 rpm unit. Comes with a single oil filled start cap. The over temp protected motor is partially embedded in one end. It draws intake air from both ends. With no back pressure... in free air, it's 765 cfm on high speed..... and down to 320 cfm @ .9" water pressure. They installed clip weights to some of the impellor blades.... so it's perfectly balanced from the factory... like balancing a car wheel. Later..... Jim VE7RF

Gents This may well be old news to some... but Coaxial Dynamics makes a 25 kw slug.[2-30 mhz].. for a standard 7/8" line section....cheap. They also make the usual 10 kw 5 kw.. 2.5 kw qrp slugs. It's Not on their website.. nor catalog... but has been around for years. I'll dig up the model number and post it in a few days. Fits the Bird 7/8" line sections too ! The 7/8" line sections all have a huge 3/8" inner conductor tube running down the middle..... where they then neck it down to the small diam... to take the QC [quick connector's]. They also make 7-16 DIN QC connector's [male or female] for both the 7/8" + 1 5/8" line sections. You can also get 7/8" EIA flange connector's as QC connector's. Any QC connector will fit either a 7/8" line section OR a 1 5/8" line section. The 1 5/8" line section requires an adaptor plate... in order to accept the QC connectors. My buddy in Ohio tells me you can also get 50 kw 2-30 mhz slugs... but didn't say what size line section it was designed for. later...... Jim VE7RF

All, I started editing the page on transformers at Wikipedia at 6:00 PM this evening, and it is now 4:30 AM in the morning. I corrected a few errors from others plus added a complete section on steel used in transformers. I also added more in the formulas concerning designing transformers using the square inch measurement for the core. In other words, I showed the converted metric to inch formulas. I also showed references to any books I used throughout the page. Below is the links on some of the sections I corrected, modified, or wrote new. http://en.wikipedia.org/wiki/Transformer#Elementary_analysis http://en.wikipedia.org/wiki/Transformer#The_Universal_emf_equation http://en.wikipedia.org/wiki/Transformer#Losses http://en.wikipedia.org/wiki/ Transformer#Operation_at_different_frequencies http://en.wikipedia.org/wiki/Transformer#Steel_cores http://en.wikipedia.org/wiki/ Transformer#Electrical_Silicon_Steel_Types http://en.wikipedia.org/wiki/Transformer#Windings http://en.wikipedia.org/wiki/Transformer#Insulation http://en.wikipedia.org/wiki/Transformer#Shielding http://en.wikipedia.org/wiki/Transformer#Coolant That's about it folks, I'm tired and off to bed! Hopefully, some might add some additional knowledge about RF transformers as it's kind of lacking (IE ferrite types, powdered iron types, their use, etc). 73, Will

If any of you intend to series parallel Oil caps for greater V ratings... BEWARE. I did just that with 4 x 50 uf @ 4500 V units. These were each 12" tall x 8' wide x 4" thick. I got em years ago from W6RR, Roger Mace... now sk. I had one of em flash over [6900 vdc no load] . The arc occured between the steel case and the threaded rod that comes up outa the oil !! Even though these units had large cone HV insulator's out the top... the weak spot is BELOW the insulator /rubber O ring. The fix was to FLOAT all 4 of em... both from the chassis... and from EACH other ! I used a huge sheet of 1/4" thick HV Red Micarta under them... and 1/8" thick sheets of micarta BETWEEN em. End of problem. Even though mine.. and most of these oil caps have a nice grnd lug welded to the steel case... DON'T BOND it to the chassis. By floating all the cases... you will RELIEVE the stress on em... they will never arc. Treat em like lytics. There is now an abundance of huge size 350 V / 450 V / 500V lytics on the surplus market. 1600uf to 5200 uf. Lotsa joules ... which is what we want. The 1600 uf @ 450 V lytics I obtained from Fair radio yrs ago [$5.00 each] were all measured between 1900 uf and 2000 uf. They were all 3" diam x 6" long... and used # 10 machine screw terminals. I mounted 20 of em horizontally [4 rows of 5].... between two huge sheets of 3/8" thick UHMW [from the local plastic shop] We used a 3" hole saw in a modified drill press... and drilled out both sheets at same time. It all fits in a nice 19" wide short rack... with front and rear panels. The HV meter is a 0-1 ma with 10 x 2 watt, 1 meg, 2% tol series resistor's. This is my "external cap box". I used Millen Red/ Black HV connector's on it. IF using the Millen's.... either use nylon mounting screws or mount em on Micarta. Both Kings and ROWE make better HV connector's imo. Measured C is 100 uf. I built it years ago and used 50 k, 5% tol, 25 watt wire wound's across each cap. If you build one of these huge lytic stacks... use Rich Measure's 100 K @ 3 watt units across each lytic. For faster bleed down time... use a PAIR of his 100K 3 watt units across EACH lytic. With the wirewounds, I used 'L' shaped copper straps on each screw terminal... to dissipate heat. One end of the 'L' goes to the screw... the wire wound is screwed to the other end of the 'L'. With just a single 50 K resistor across each one.... HV bleeds down slowly.. a few mins. With 100 K units.... it takes longer. I recently obtained cases of 2500 uf @ 450 V lytics from that fellow in Florida. Now these newer design caps are slick... only 2" diam x 4" long.... and a whopping 9.8 A CCS ripple current rating. ESR is aprx 50 MILLI ohms each. I have 72 of em.... so I'm building 3 x banks .. with 24 caps per bank. I can use 1 or 2 or all 3 banks in parallel. To protect all this mess.... we used a BUSS HVU-3 HV sand filled fuse [ SSON has ton's of em... so does Buss... Buss has em in a huge variety of ratings]. These units are 13/16" diam on the ends... and fit a standard 3/4" fuse clip snugly. I used the 3/4" from SSON that have end retainers on em... so once inserted, there is NO way they can migrate out.. esp when mounted vertically. The surplus HV fuses from SSON are rated at 3 A CCS.. and are sandfilled. $3.50 each... in bulk. The SSON units are glass bodied.... the newer ones from Buss are Ceramic bodied... other wise, they are identical. The 5" long HV fuses are rated at 5 kv AC RMS.... and work at 8 kv DC no sweat. They also make 10" long fuses... rated at 10 kv AC RMS / 16 kv DC. I install ONE of these HV fuses... in ONE leg.... between the SECONDARY of the Dahl plate xfmr and the FWB diodes. The 2nd HV fuse goes BETWEEN the B+ output of the lytics and the HV "Glitch Resistor's" If something ever shorts out in the lytic banks.. the 1st HV fuse between sec of plate xfmr and HV diodes will save the diodes every time. With fault current... they blow REALLY fast. The 2nd HV fuse, located in the B+ line is always located BEFORE the glitch Resistor... never after. IF u flipped em around... and something happened to

Mike, I bought a bunch of these SHV connectors and bulkheads from Powell, a Kings stockist/distributor. rmilligan@... , Ryan Milligan from Powell was kind enough to send a handul of these conector over the pond to The Lowlands. However, I do not like them. They are in physical terms too flimsy and do not accept a 11 mm coaxial cable for HT connection purposes. Currently my 3 phase HT psu is connected to the desktop RF deck wit a silicone insulated coaxial cable which is hard wired on the choke in the amp and on the cap stack in the 3 phase HT psu. Cheers, Dick PA3DUV .

wrote: full ### Peter, et all ### I had an engineer buddy of mine cook up a high reflected power shut down circuit for me. My buddy got a hold of a ton of Bird single line sections. He joined two of em together with some brass rod and soldered the outside flanges... to fabricate a "double line section". ### He made two such assemblies. We installed one on the input of the amp... and the 2nd one on the output. [4 x slugs installed] ### Since the big amp is remoted 30' away from the shack..... we had to be able to read all 4 x line sections in BOTH locations. My engineer buddy designed a peak reading board that would work with all 4 x line sections.... and continuously monitor the PEP reflected power from the ant [line section # 4 ] ### Only one bird 30 ua meter is used in each location.... and either end can be switched independently to any of the 4 x line sections. He used line drivers at the amp end.. to drive the box in the shack. ### The high PEP reflected power threshold is fully adjustable... and in this case was set to 1 kw. When the threshold is exceeded.... a minature dpdt relay operates [ in <2 msecs] and one set of contacts applies -10 vdc to the ALC jack of the Yaesu MK-V.... shutting it down asap !! ### The 2nd set of conatcts activates a 2nd, identical relay [also in < 2 msecs] ### This 2nd DPDT relay opens up the key line to both the IPA [ intermediate pwr amp] and also the 12 kw amp. The circuit latches.... and lights a red led. A spring loaded push button resets the circuit . [AFTER you find out why the high swr condition occured] ### Since the 2 x minature relay's are sequenced.... the ALC shut down on the xcvr occurs 1st.... followed by kicking BOTH amps off line ! NO Hot switching! ### To key both amps.... I used a PAIR of P+B opto isolators.... they run on +13.8 vdc @ 10 ma each. The "electronic TX ground" from pin 2 of the MK-V's band data jack supplies the grnd to both opto's on TX. ### The output side of each opto is rated at 200 Vdc @ 1 A CCS. They also have 4 kv isolation between input and output... and operate in under 100 microseconds. Cheap too. ### We used +120 vdc to operate all 4 x vac relays in the big amp. [speed up circuit, with a pair of dropping resistors] ### The high swr circuit could have been configured to open off the INPUT to both opto's instead.. of the Opto outputs. Moot point. ## I had my engineer buddy also include a short 12-14 msec delay... used in conjunction with the yaesu "TX inhibit lead" [used on both the 1000-D... plane MP.... MK-V /field. ## BOTH amps are keyed NOW.... after 10-14 msecs... TX inhibit is removed... allowing full power from the Yaesu MK-V. ### This delay ensures the vac relays won't hotswitch on TX... even though all 4 x are sped up.... we are using RJ1A's on the input side [one for drive RF... the 2nd RJ1A shorts out the 100k resistor to remove the cutoff bias. We paralled a pair of larger, slower vac relays on the output 10 kw side. ### We didn't want a situation where input relays operated 1st... drive applied to cathode... and no ant connected ...yet !! ### This delay circuit is for SSB / FM /AM ### In the MK-V menu.... on CW only.,... you can delay the RF by 0-30 msecs [ digital delay... NOTHING gets truncated either] ... and still key the amps in real time... NOW. It needs to be set between 10-30 msecs. ## The above T/R scheme is super fast vox cw/ ssb /fm /am. Due to the 'slower' larger vac relays on the 12 kw output side....qsk is not recomended. ### If anybody is interested.... the high swr circuit will be made available down the road... along with the rest of the schematics. It's saved everyones bacon a few times so far... works slick... and works on any bird line section / slug size. Later......... Jim VE7RF

Greg, Thanks for info. Your statement on the Powerpoles for HT use is amazing. Did you test the small Powerpoles (30-45 amp) or the larger 75 amp models? One thing is very important though; for HT connectors, beside the HT rating, it is VERY important to have the connector arranged in such a way that ground makes contact long before B+ in order to prevent the RF deck to become on B+ potential any time. I cannot see a Powerpole meeting this. Also I use a second ground connection from the HT psu to the RF deck. This ground connection is wired in the control cable connector and provides the needed redundancy. Cheers, Dick PA3DUV

I couldn't resist. To make a 40-10m choke balun for 40-10m yagi's use type 43 beads [1" OD x .5" ID x 1" long] slid over RG-393 teflon coax. The balun is 17" long when completed [16-17 beads.] The Z at 7 mhz is 1350 ohms. On 10/12m... power rating is 8500 watts CCS dead cxr. For 75m it has to be 24" long [1350 ohms Z.] For 160m, it has to be 30" long [1350 ohms Z] And no... 500 ohms Z is NOT enough... take ur ARRL ant book ...and toss it ! 10 turns of 10" diam 213 u won't work on 75m either.... too low a Z. Coiled up coax in a solenoid is a huge windload... and a pain to manhandle on a tower. When using [expensive new] 393 teflon high power coax... the last thing u need is a megabuck worth of coax to make a solenoid. Besides.. a real linear will cook 213 u on 75m. Type 43 is bomb proof... and cheaper than the type 77 beads [type 77 is shorter .81" long] Type 43 beads are still $2.00 each.... the inferior type 77 are $3.00 each. They are cheaper still... in bulk from Amidon. You can also get em pre-made from Ken Hirschberg at Cal-Av labs..[and also from Jay Terleski at Array Solutions].. comes with a 7-16 DIN... and teflon coated 10 ga wires. His are pumped with silicone glop... under pressure.. then bubbles removed in a vac chamber. All siver soldered to boot. The teflon wires are unique. Each layer of fine wires is reversed in twist cw.. ccw...cw...ccw etc. End result is... when u form the 10 ga wire.. it stays put !! Won't spring back....slick. You can't blow these babies up if you tried. They won't heat up either. Best Balun ever made... period. You can pump 15 kw into em all day long. The boys on the contest reflector finally figured out the same thing. The typ W2DU baluns using 303 teflon coax.. and the tiny type 75 beads would heat up with just a 500 w dead cxr on all bands from 1.8 to 30 mhz. They switched to type 43 small beads... and the same small 303 teflon coax.[slightly longer.. more beads] They ran the exact same test as b4..... except 2200 watts.... zero heat ! I use type 43 for all my bifilar rods as well. [for fils of thoriated tungsten fils] .. but that will be another story. Later.... Jim VE7RF

Let me correct this: Jim said: This is my "external cap box". I used Millen Red/ Black HV connector's on it. IF using the Millen's.... either use nylon mounting screws or mount em on Micarta. Both Kings and ROWE make better HV connector's imo. Where can one find the Kings or Rowe connectors? The only thing I have in my junk box are the Millen Red and the brown phenolic. I understand the brown ones *aren't* very good. However, my local parts jobber confided in me that the Millen connectors were supposedly rated for 4500 VDC. Mod-U-Lator, Mike(y) W3SLK

Am 23.09.2006 um 15:41 schrieb pentalab: I'm dying to see some beautiful pictures of all those neat things you describe... Please be so kind and put some into the photos area of this group on yahoo. Mni tnx de Frank DG1SBG

I have been using Belden 10 KV test prod wire for the last several years.... comes in red/black. I use both red/black on everything......... vey flexible.... abot .21" diam.... silicone rubber. Many fine strands inside. Test V is 29 kv. Funny thing is, the smaller 5 kv test prod wire has a test V of 20 kv.... go figure. My real concern using this stuff EXTERNALLY like between RF deck and HV supply... or HV supply to an external cap box is it would appear to be very easy for something to cut through it. It needs to be re enforced on the outside. Back in 1976... our local emporium had 40 kv stuff.... but had a solid teflon dielectric... was stranded inside... and NOT very flexible. Anybody know the V rating on RG-303 TEFLON coax ??? My other idea was to place the Belden 10 kv silicone test prod wire INSIDE some plastic tubing. I also saw VERY flexible aluminium BX sheath material at home depot. Also saw the flexible plastic tubing with the slit all the way through it... to make life easier getting wiring inside it. I have seen some fellows place the HV supply very close to the main 200 A breaker panel..... then run longer lengths of HV wiring... sometimes inside conduit... to the remoted RF deck. The idea there was to minimize V drops in the 240 wiring. The peak current every 8.3 msecs in the 240 V ac line is unreal.... like almost 4-6 X. Later...... Jim VE7RF