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Re: NOS cermic-metal tube burn in
On Nov 17, 2006, at 9:18 AM, Robert B. Bonner wrote:
Sounds like the heat dam problem. Appsaently the problem lasted c. 13-months. I have not heard of the 3cpx1500A7 having a heat damn problem. What is the date code? A knowledgeable engineer knows that paralleling tubes makes 10m...*** Yeah, there you go. But still no self respecting Collins operation no more difficult than doing it with one tube. cheers, Bob R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: NOS cermic-metal tube burn in
pentalab
--- In ham_amplifiers@..., R L Measures <r@...> wrote:
a 2.7KHz mechanical filter -- i. e., one that was wide enough to... and the audio quality is superb.They were better than later Collins transmitters because they used pass a humanoid male voice with minimal loss of lows. Later Collins transmitters used a 2.4KHz filter, which is wide enough for female voices but NOT male voices. ### Huh ? Most women sound like crap on a ssb Tx.. simply cuz the upper freq response doesn't go high enough. Later Collins S-line KWM2/A rigs all used a single 2.1 khz mech filter.. with lousy skirts. ### I installed a 5.7 khz 10 pole Collins mech filter in all my Yaesu FT-1000-D's and also my Yaesu MK-V's. Also beware, Collins spec's their mech filter's at the -3db points... NOT the -6db points !! My 5.7 khz filter is actually a little wider at the -6db points. This filter of course is used at the 455 khz IF. The 8215 khz xtal filter was replaced with a Inrad 6 khz [-6db] 8 pole, steep skirted unit. Each filter has a 1.5 : 1 shape factor..... and cascaded.. the PAIR have an excellent 1.3 : 1 shape factor ! ### with that combo... then you can have really good sounding ssb... as good or better than our local 10 kw AM broadcast station. ### We also found that by replacing the analog BM pot with a 10-20 turns pot, OR paralleling a resistor with existing pot... that an easy -75 db of CXR rejection is obtained.... and that's with the cxr osc tweaked for just 30 hz @ -6db . With cxr osc set to 300 hz.. @ -6db.... cxr suppresion is >100 db... superb. other than those like that of Verne Troyer, a.k.a. "Mini Me" of Austin Powers movie fame.Hams who run AM are lock-to-talk time-wasters.I'm more of a KW-1 fan onlyI am not a fan of AM because it's a watt-waster and most of the #### I use VOX AM... works superb. Also, you can install a wider AM filter in the yaesu MK-V's... for deluxe AM. You can see all of this info on the 85 page document W5CUL and myself wrote... posted on also on .. under MK-V mods. tubesI think the Collins #### Six 8170's would make some racket too.in themAgreed, Bob, but in those days the choices were few between the later.... Jim VE7RF ... |
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Re: NOS cermic-metal tube burn in
Robert B. Bonner
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-----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of R L Measures Sent: Friday, November 17, 2006 5:55 AM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in On Nov 16, 2006, at 1:30 PM, Robert B. Bonner wrote: Below,To check emission capability for Class AB1 operation, one must (very briefly) measure the anode-I at 0 grid volts. *** OK I'm sureDo you have access to a high-potential tester? *** Currently no, I put the tube into one of my ham amplifiers and fired it up. Did you autopsy the tube, or did you base this diagnosis on ohmmeter measurements? *** In the case of the 8877 back in 1980 it was pretty obvious the amp was working one day and then when fired up the next one of the tubes wasn't home. I did the pull one out at a time to figure out which one didn¡¯t come online and then placed the calls. I checked filaments and both tubes were OK. All the cathode pins were still connected together. But apparently something else had stopped working. The tube was returned to Eimac and they did the autopsy. They informed me of the result and that it was a warranty issue and that the tube would be replaced. On the next production run I received a new tube. At that time the whole process took about a month. During that time the amp was reconverted back to a 77DX and I sold it. :-( The new owner wanted it converted back and provided the money to start building 77 conversions. This led me down the road to many 77 console conversions and eventually the 77DD amplifier. What failed? *** A weld in the actual cathode, I never saw the tube again. But the pins stay connected and the cathode separates from the pins. I figure this 3CPX1500 has the same type of failure, though not a warrantee able situation in this failed in an MRI machine tube. They were better than later Collins transmitters because they used a... and the audio quality is superb. 2.7KHz mechanical filter -- i. e., one that was wide enough to pass a humanoid male voice with minimal loss of lows. Later Collins transmitters used a 2.4KHz filter, which is wide enough for female voices but not male voices other than those like that of Verne Troyer, a.k.a. "Mini Me" of Austin Powers movie fame. *** OK. While I've never personally owned a KWS-1. I did a really large trade at one time in Collins gear. I have owned many late S-Lines however not any recently. My personal keeper at the time was a 32S-3A with a DX engineering processor and a D104. Coupled to a reasonable amplifier (30S-1, Homebrewed 3-1000, and finally a Harris RF-103A) and a big antenna I had a beautiful sounding signal. I had just graduated with my bachelors, took my first apr¨¨s-school job. Bought a small house that just happened to have a Telrex Bertha in the back yard. Not too bad at 24... SO I took down my 160 foot 55G on the lake at my parents home and moved to town. Back during that cycle I was quite the DX hog. I'd spend the evenings going up and down 20 meters working everybody. AT least once an evening or more the DX would say.. BOB, you were not the loudest signal in the pileup, but I just had to come back to YOU as you have the best sounding audio I have ever heard. It did have good punch. And it did sound good. I have spent the next 26 years attempting to get the audio sound back. IT HASN¡¯T EVER HAPPENED. Which is a huge disappointment. I've tried every different rig, played with audio... There is no way to duplicate the Collins mechanical filter without a Collins mechanical filter... I think to finally get what I'm looking for will require implementing these components. I'm more of a KW-1 fan onlyI am not a fan of AM because it's a watt-waster and most of the Hams who run AM are lock-to-talk time-wasters. *** Yes no AM is just a toy. Most of my time is spent fast break SSB (not vox) talking to my buddies from 35 years ago still or working DX. I think the CollinsAgreed, Bob, but in those days the choices were few between the 7580/4cx250R and the 8170. They of course wanted a transmitter to match the 75A-4 butSix of them in parallel would have been about right for the then legal 1000w DC indicated input on SSB. *** Yeah, there you go. But still no self respecting Collins engineer would ever stick 6 in a box and call it a day. Then Collins would not be a collector's item but stacked in piles next to Galaxy sweep tube KW's. BOB DD ... R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org Yahoo! Groups Links |
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Re: Big Tubes on the Desktop?
On Nov 17, 2006, at 6:57 AM, n6jp wrote:
Jer: With the aforementioned cooling air-pressure, RTTY would require that the anode PS potential be reduced to c. half of that for SSB. This is semi-easy if the HV-PS is FWD/FWB switchable.This is somewhat less than wonderful. OTOH, with an 8171 at sea-Rich, using a 8171, what specs would you recommend for a mode such as end R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: Big Tubes on the Desktop?
This is somewhat less than wonderful. OTOH, with an 8171 at sea-Rich, using a 8171, what specs would you recommend for a mode such as rtty? Jer
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Re: Big Tubes on the Desktop?
On Nov 17, 2006, at 3:04 AM, badgerscreek wrote:
Anyone built a desktop amplifier with a very large tube, say aYes, I built an 8170 amplifier, however, the 8171 is the same tube inside but it has a more efficient anode cooler which works ok with a 1700rpm blower instead of a 3400rpm one. Greg -- An 8170 at sea-level with 0.4 inches of water-column is good for 2000w dissipation. Since the required ZSAC for good linearity is 0.5A, 2000w would limit the anode supply to c. 4000v. Since the usual screen potential for an 8170 (or 8171) is 1300 to 1500 volts. a 4000v anode supply would allow only about 2500v of anode headroom. This is somewhat less than wonderful. OTOH, with an 8171 at sea- level using 0.4-inches of WC will dissipate c. 4500w. This allows using a 9000v anode supply - but only for SSB. Thus, on SSB with a 1500v screen supply, the headroom is 7500v. The bottom line is that with 0.4" of cooling, the 8171's output is c. 3x greater than 8170's output. At 9kV and 1500Sc-V, an 8171 should do c. 19k-pep out on SSB. If you have a good-emission 8170 and you would like for it to have an 8171 anode cooler, the anode cooler can easily be swapped out by a tube rebuilder. end R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: NOS cermic-metal tube burn in
On Nov 16, 2006, at 1:30 PM, Robert B. Bonner wrote:
Below,To check emission capability for Class AB1 operation, one must (very briefly) measure the anode-I at 0 grid volts. I'm sureDo you have access to a high-potential tester? Did you autopsy the tube, or did you base this diagnosis on ohmmeter measurements? What failed? They were better than later Collins transmitters because they used a 2.7KHz mechanical filter -- i. e., one that was wide enough to pass a humanoid male voice with minimal loss of lows. Later Collins transmitters used a 2.4KHz filter, which is wide enough for female voices but not male voices other than those like that of Verne Troyer, a.k.a. "Mini Me" of Austin Powers movie fame.... and the audio quality is superb. I'm more of a KW-1 fan onlyI am not a fan of AM because it's a watt-waster and most of the Hams who run AM are lock-to-talk time-wasters. I think the CollinsAgreed, Bob, but in those days the choices were few between the 7580/4cx250R and the 8170. They of course wanted a transmitter to match the 75A-4 butSix of them in parallel would have been about right for the then legal 1000w DC indicated input on SSB. ... R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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]Re: NOS cermic-metal tube burn in
Hsu
¿ªÔÆÌåÓýThanks who reply my question.
? Sorry for my bad English,
??? The KWS-1's origional tubes are
4CX250R, All OK, without any problem.full output(500-600W).
?? But my friend replace?with a pair
?Chinese NOS FU-251F, the output power? only 300W orso.
? the anode current can reach 400-500ma( a pair)
if change the bias, I think the tube is good.And same
a group(? not this pair,but with same date
code)tubes, I insert?them?to a old Chinese? 400W SSB transmitter,
All OK.output is 500W orso.I do not know the
reason.About durability of Chinese 4CX250(FU-251F), one of my
friend, a? retire??Lieut.Col., service engineer has bee told me
that Chinese FU-251F can use 1-2 years( depend on?the brand, Jingguang is
the best)?in 400W CCS output tranmitter in very hard to use( often
transmitting for?very lony time even 2-3 hours, and all day ,24 hours
?power on).
?I think it is a not too bad.But maybe the American
product is?bettar than Chinese product.?
??? Thanks again!
?????????????????
Hsu
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Re: NOS cermic-metal tube burn in
Robert B. Bonner
Below,
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-----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of R L Measures Sent: Thursday, November 16, 2006 2:48 PM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in On Nov 16, 2006, at 11:06 AM, Robert B. Bonner wrote: RL,I wondered about that problem after I clicked Send. However, if the tubes will draw 500mA, there can not be a lack of emission provided they do that briefly at 0 grid volts. **** Yes exactly, the emission seems good by rocking the bias. Have to be careful here as 400ma is 800 watts dissipation. But if it was just a quick check... I'm hoping he's not going all the way to zero control grid volts, I'm sure he's just moving it a bit. That's why I figured the issue is alignment and driver power. Or possibly some other issue not finals related. We'll have to wait for his response to the questions. I've seen a number of Eimac pulls that were kaput. ****I was referring to new old stock 4CX250's the 20 year old ones or more, they just seem to keep right on ticking no matter where you get them from if new. Pulls are always a crap shoot. I just had a beautiful 1 YO 3CPX1500A7 test bad last night. Obviously a hammered cathode as it drew no plate current, made no grid current or RF. But the filament warmed up nicely. This one was a new tube placed in an MRI and it faulted... Obviously the fault was a violent one. Really too bad, I was getting emotionally attached to that tube, now I need to send it back to the guy. I had thought I had a great purchase there. I had a new low hours 8877 back in 1980 do the same thing without a fault. There was a time that Eimac had issues with quality on the 8877, a weld came loose INSIDE the tube separating the cathode from the pins. Just after turning it on when keyed my 77SX went to half resting current. This was my amplifier and I just about lost it. I worked for a medium sized Eimac dealer at the time. I talked directly first to Eimac, then ETO and since that tube was within warranty I went through all the standard return paperwork. They tore the tube apart and in fact it was the warrantable quality failure problem and they sent me a new tube. ... and the audio quality is superb. **** Yes for an early SSB rig they were great. I'm more of a KW-1 fan only because they were total brutes. I'm sure you agree. I think the Collins engineers sort of let us down a little by not putting bigger tubes in them from the start. They of course wanted a transmitter to match the 75A-4 but still. The 4X150 was a sexy little tube. I wonder if we would have ever seen an S-Line if the 4CX1000 would have been available in the 50's? Something to think about. cheers, Bob. ... R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org Yahoo! Groups Links |
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FW: NOS cermic-metal tube burn in
Robert B. Bonner
Because he adjusted the BIAS to make the 400-500 ma of resting plate
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current. You have to very closely read his message. There's a very slight language barrier. That's why I'm wondering a couple things. Curious what tubes were in the transmitter previously... and if the unit makes full power with a different set of tubes. I'm thinking these 4CX250's are quite possibly just being difficult. It doesn't take much to detune the driver tuning and lose drive. I'm not familiar with the durability of Chinese 4CX250's in storage, but the Eimac ones are like concrete. Seems you can pull an Eimac one out of the soup and crank it up any day of the week. The KWS-1 is a persnickety device in the first place, but once lined up they work well. I don't necessarily recommend going after it with a diddle stick without knowing more about it working with other tubes and the unit's condition. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of R L Measures Sent: Thursday, November 16, 2006 12:14 PM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in On Nov 16, 2006, at 9:26 AM, Robert B. Bonner wrote: Hsu,So why is there 500mA of anode-I? Its been a long time since I've tuned up a KWS-1. The ones IR L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org Yahoo! Groups Links |
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Re: NOS cermic-metal tube burn in
On Nov 16, 2006, at 11:06 AM, Robert B. Bonner wrote:
RL,I wondered about that problem after I clicked Send. However, if the tubes will draw 500mA, there can not be a lack of emission provided they do that briefly at 0 grid volts. I've seen a number of Eimac pulls that were kaput. ... and the audio quality is superb. cheers, Bob. ... R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: NOS cermic-metal tube burn in
Robert B. Bonner
RL,
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Because he adjusted the BIAS to make the 400-500 ma of resting plate current. You have to very closely read his message. There's a very slight language barrier. That's why I'm wondering a couple things. Curious what tubes were in the transmitter previously... and if the unit makes full power with a different set of tubes. I'm thinking these 4CX250's are quite possibly just being difficult. It doesn't take much to detune the driver tuning and lose drive. I'm not familiar with the durability of Chinese 4CX250's in storage, but the Eimac ones are like concrete. Seems you can pull an Eimac one out of the soup and crank it up any day of the week. The KWS-1 is a persnickety device in the first place, but once lined up they work well. I don't necessarily recommend going after it with a diddle stick without knowing more about it working with other tubes and the unit's condition. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of R L Measures Sent: Thursday, November 16, 2006 12:14 PM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in On Nov 16, 2006, at 9:26 AM, Robert B. Bonner wrote: Hsu,So why is there 500mA of anode-I? Its been a long time since I've tuned up a KWS-1. The ones IR L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org Yahoo! Groups Links |
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Re: NOS cermic-metal tube burn in
On Nov 16, 2006, at 9:26 AM, Robert B. Bonner wrote:
Hsu,So why is there 500mA of anode-I? Its been a long time since I've tuned up a KWS-1. The ones IR L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: NOS cermic-metal tube burn in
Robert B. Bonner
Hsu,
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200 watts out, it sounds like he is not getting adequate RF drive to the finals. Its been a long time since I've tuned up a KWS-1. The ones I worked on (back in the 70's) were both 4X150 powered units, not 4CX250. Does the unit make a KW with another set of tubes in it? It sounds like with adjusting the bias you can draw current with the tubes. But if the transmitter doesn't make RF drive it cant make output. Could just be an alignment issue with the tube change. I don't have a manual for that transmitter here. BOB DD -----Original Message-----
From: ham_amplifiers@... [mailto:ham_amplifiers@...] On Behalf Of R L Measures Sent: Thursday, November 16, 2006 3:32 AM To: ham_amplifiers@... Subject: Re: [ham_amplifiers] NOS cermic-metal tube burn in My guess is that the wattmeter is in error. On Nov 15, 2006, at 4:58 PM, Hsu wrote: R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org Yahoo! Groups Links |
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Re: Pseudo Grid Current
On Nov 15, 2006, at 5:54 PM, craxd wrote:
It's a possibility that the reason the plate choke did what it didDoes the choke exhibit a self-resonance c. 95MHz when it is in place? If it looked like someone had been playing aroundR L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: NOS cermic-metal tube burn in
My guess is that the wattmeter is in error.
On Nov 15, 2006, at 4:58 PM, Hsu wrote: R L Measures, AG6K, 805.386.3734 r@..., rlm@..., www.somis.org |
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Re: Pseudo Grid Current
craxd
It's a possibility that the reason the plate choke did what it did
was over the amp being ran at a frequency where the choke would have went self resonant. If it looked like someone had been playing around with the tank coil taps, that could have been what happened. You may be able to remove a few turns from the top and save it. Use a dip meter to see what its self resonant frequency is, and that it's not in the operating bands of the amp. I would check the complete meter circuit out and add the modifications Rich mentioned. Best, Will --- In ham_amplifiers@..., jmltinc@... wrote: repairing in my spare time. Amongst the defects it had, was a plate choke flash-over. This took out the .5 ohm (20 watt?) resistor and diode (on the powersupply) that hold the B- to near ground potential. It also took out a small(.1?) cap at the plate current meter (in the desk console). The schematic is notcorrect for this unit and Henry was no help. I did what I think is correct."grid current", but plate current. See the table below for results:Out follows the plate current. Hmmm...grid meter, here is a .5 ohm resistor shunt from ground to cathode with a 470ohm, 3 Watt series dropping resistor from the cathode side of the shunt to thegrid meter. (The other side of the meter is grounded).from the glitch R to the cathode. The meter is connected across this with a150 ohm series dropping resistor between it and the shunt R / glitch R connection. |
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