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Author Topic: 6146??? 6146B - w  (Read 9756 times)
KD0REQ
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Posts: 2023




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« Reply #15 on: September 11, 2017, 12:43:35 PM »

did you neutralize the tubes in the new rig? yah, yah, yah, negligible differences Cpg Cps etc. they put neutralization instructions in the manual for a reason.
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KB2WVO
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Posts: 382




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« Reply #16 on: September 11, 2017, 01:50:59 PM »

did you neutralize the tubes in the new rig? yah, yah, yah, negligible differences Cpg Cps etc. they put neutralization instructions in the manual for a reason.
iam lookin thru the build manual i see nothing .. on the rite way to do it for this rig.. iam sure its a basic idea. but i would like to be 1000% sure on how its done ..
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KD0REQ
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« Reply #17 on: September 11, 2017, 02:08:57 PM »

To expand... power tube specs are rated in a band of ranges. They indicate manufacturing tolerances, and the chances of two random tubes matching what you had installed are not great. This means different gains and thus different reactions to stuff around them. So on changes of power tetrodes, you have a different system at RF. So you need to neutralize and likely change the drive level. The equipment intolerant of 6146B tubes do not have a wide enough neutralization range (or none at all, if the designers intended you buy their own selected tubes.)
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KD0REQ
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« Reply #18 on: September 11, 2017, 02:13:31 PM »

Neutralization is generally capacitive, a trimmer or bendable wire or plate. Generally, you take the B+ off the plates, set a CW signal on at the top frequency, and adjust the measured output down to some value with the neutralization cap. If your manual does not have the directions, ask around.
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KB2WVO
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Posts: 382




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« Reply #19 on: September 11, 2017, 04:30:32 PM »

Neutralization is generally capacitive, a trimmer or bendable wire or plate. Generally, you take the B+ off the plates, set a CW signal on at the top frequency, and adjust the measured output down to some value with the neutralization cap. If your manual does not have the directions, ask around.

ill have to check around for a heathkit group of some sorts.. this old girl is in great shape.. untouched for 22 years. as i owned it 22 years ago.. sold it and got it back sunday .. and the old valves that were in it them were still in it..

so a good goin over might be in store. and the ham i sold it to. knew tons more then i ever will.. tho he is SK now. sadly missed to ..

lil by lil ill figure it out i guess. lots to learn for sure. the fun of the hobby .. never stop learning something new every day .
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KD0REQ
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« Reply #20 on: September 11, 2017, 06:24:57 PM »

on the classic Heathkits, the instructions are the same for the HW-100, 101, SB-100,101, 102.  it's in all those manuals, floating around behind the build instructions.  you lift two wires on a terminal strip, and follow the instructions.  danger, warning, fattening, that's up to 800 volts, spark it off to ground and unplug the power supply from the wall, just in case, before lifting the B+ and before replacing it. the circuitry is almost identical one to the other, especially in the final cage.
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KB2WVO
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« Reply #21 on: September 11, 2017, 07:50:09 PM »

i read thru the manual. found the area.. its under transmitter alignment..
about 20 or so steps.. and iam about 99% sure it hasnt been done in at least 22 years..
so iam reading it a few 100 times to absorb it. and understand it a lil..

lordy i love radios.. so much fun..
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KB2WVO
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Posts: 382




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« Reply #22 on: September 11, 2017, 10:01:37 PM »

on the classic Heathkits, the instructions are the same for the HW-100, 101, SB-100,101, 102.  it's in all those manuals, floating around behind the build instructions.  you lift two wires on a terminal strip, and follow the instructions.  danger, warning, fattening, that's up to 800 volts, spark it off to ground and unplug the power supply from the wall, just in case, before lifting the B+ and before replacing it. the circuitry is almost identical one to the other, especially in the final cage.

will not trusting the meter on radio persay.. i did the neutraliz with a xtern watt meter. got her stable at around 80 watts on 50.125. thats fine for now. and thats with the old 6146A's that were in it. that i resoldered the tophat on .. darn thing is just slidin rite along. friend is goin to post video of how i sound form his side.. ill post link for it .. also when he spoke from my side. video will be posted for those who like to see.

https://youtu.be/RZjpQ8bCLec
« Last Edit: September 11, 2017, 10:21:50 PM by KB2WVO » Logged
G3RZP
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Posts: 8143




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« Reply #23 on: September 12, 2017, 01:49:21 AM »

One point to note with all the 6146 family is that the specification allows for given plate, screen and bias voltages for the plate current to vary over approximately a 2:1 range. So if the tubes are not matched, you could set the bias for 50mA for two tubes and in the extreme, have one tube drawing 16.6mA and the other drawing 33.2mA. Tubes from the same batch tend to match reasonably well, which is how you get away with it in manufacture, but it is not quite so easy these days to find tubes from the same batch.
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K1ZJH
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« Reply #24 on: September 12, 2017, 01:08:46 PM »

One way to check neutralization quickly is to see if the plate dip (when tuning the plate) coincides with maximum power output.  If power out increases either side off of resonance--the lowest plate current dip, it might indicate the neutralization is incorrect.  Just a tip for the future.

Pete
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G3RZP
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« Reply #25 on: September 13, 2017, 01:00:04 AM »

 I basically agree Pete, but there can be a problem in that most rigs measure cathode current and the dip in plate current corresponds to a peak in screen current: especially if the screen supply isn't well regulated, this can result in misleading answers. Something to be aware of...A lot depends on the ratio of screen to plate currents, so the test is best done at full power where the ratio is greatest.
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KB2WVO
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Posts: 382




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« Reply #26 on: September 13, 2017, 07:48:10 PM »

One way to check neutralization quickly is to see if the plate dip (when tuning the plate) coincides with maximum power output.  If power out increases either side off of resonance--the lowest plate current dip, it might indicate the neutralization is incorrect.  Just a tip for the future.

Pete

pretty darn close.. like neddle width.
now to get the 101zd in tune. grrrr... i get almost all bads but 15 i think it was that would oscar on itself..  o will no big hurry with it. probey could use a recap .. and alignment. and and lol
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N2DTS
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Posts: 748




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« Reply #27 on: September 15, 2017, 12:12:36 PM »

There are differences between 6146, 6146a, 6146b and 6146w tubes.
You need to adjust the radio to the tube type, mostly the grid circuit as the tubes will have different amounts of capacitance and the grids are in a resonant circuit.
On some radios the preselect knob tunes the grid circuit as they use it as a preselector on RX.

Read the manual carefully. Be aware of the high voltage, turn off and short to ground before touching anything, use insulated tools for adjustments.
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KB2WVO
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Posts: 382




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« Reply #28 on: September 15, 2017, 04:16:43 PM »

There are differences between 6146, 6146a, 6146b and 6146w tubes.
You need to adjust the radio to the tube type, mostly the grid circuit as the tubes will have different amounts of capacitance and the grids are in a resonant circuit.
On some radios the preselect knob tunes the grid circuit as they use it as a preselector on RX.

Read the manual carefully. Be aware of the high voltage, turn off and short to ground before touching anything, use insulated tools for adjustments.
i need to learn the inereds of tubes. as i will be goin thru the radio down the road for a tune up and such.

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AK0B
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Posts: 269




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« Reply #29 on: September 29, 2017, 09:24:17 AM »

6146 series of tubes are very sensitive to gird current.  I love the them but have destroy several by over driving the grid.  I no longer use them for that reason.  I seem to remember 2 ma would give full output on CW.

Stan ak0b
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