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Author Topic: Power out increases until the load cap is 100 % meshed  (Read 13532 times)
KM4AH
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Posts: 955




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« Reply #30 on: February 03, 2018, 01:35:57 PM »

All right then fine but if you are called upon to make repairs why not do it right?  The correct load cap is about $35.  Cheap is dear.  You get what you pay for. 

Well, If it can be explained to me why it will play one bit better with the correct loading cap than it will having to add another pad for 40 meters maybe I will.


It will increase the tuning and impedance matching range.


I understand. But, it tunes fine where it is going to be used.
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K9AXN
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« Reply #31 on: February 03, 2018, 02:12:04 PM »

What is the difference in the tuning range capacity of the stock and what is in the radio?
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W8JX
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Posts: 13268




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« Reply #32 on: February 03, 2018, 07:29:15 PM »

All right then fine but if you are called upon to make repairs why not do it right?  The correct load cap is about $35.  Cheap is dear.  You get what you pay for. 

Not sure why he needs to buy a cap if after he swapped 40m and 80m caps he said 40 tunes better and 80 about same as before.
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Ham since 1969....  Old School 20wpm REAL Extra Class..
W1QJ
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Posts: 2966




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« Reply #33 on: February 04, 2018, 07:25:30 AM »

All right then fine but if you are called upon to make repairs why not do it right?  The correct load cap is about $35.  Cheap is dear.  You get what you pay for. 

Not sure why he needs to buy a cap if after he swapped 40m and 80m caps he said 40 tunes better and 80 about same as before.

Ok then, end of thread problem solved.
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AF6LJ
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Posts: 582




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« Reply #34 on: February 04, 2018, 09:56:52 AM »

That will be the simplest thing to try. The tuning is such that the Load Cap on 75 has little dramatic effect. I mean you can find a peak output, but 1/4 turn in either direction won't make 50 watts out difference. Matter of fact on 40 you can unmesh the cap from 0 up to 20 on the dial and won't lose 50 watts. Running about 75 watts drive and 1200 or so out.

Try swapping both, placing 80m 750 pf on 40m and 40m 500 pf cap on 80.


Well, I can drive it with 200 watts if necessary and try what QE says.

I can swap them easy enough, famous last words.
Have you checked the input VSWR to make sure the transmitter is seeing a more, or less fifty ohm load??
That will cause the same thing to happen.

I will. Just finished putting a floor pan in my 81 F150. Worn out right now.
After a job like that I wouldn't want to do much ether. Smiley
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Sue,
AF6LJ

Don't Kalifornicate My Life
W8JX
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Posts: 13268




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« Reply #35 on: February 04, 2018, 10:19:45 AM »

I will. Just finished putting a floor pan in my 81 F150. Worn out right now.
After a job like that I wouldn't want to do much ether. Smiley

Want to try some fun? Yesterday I changed the fuel pump on a friends Volvo AWD in a parking lot in cold in wind. You have to remove rear seats and access plates under then to get to fuel pump in tank. But, to make matters worse the AWD tank is one piece tank split into two chambers connected with a runner over rear drive shaft and pump and sending unit installs on one side and then you have to fish a remote pickup for pump to other side which also has its own sending unit. (so you get to play in gas with hands in cold too.  Top that off with a bastard 4 inch plastic nut that holds units in that needs a special wrench. Fixing a floorboard by comparison would be a piece of cake. 
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Ham since 1969....  Old School 20wpm REAL Extra Class..
AF6LJ
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Posts: 582




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« Reply #36 on: February 04, 2018, 10:37:55 AM »

I will. Just finished putting a floor pan in my 81 F150. Worn out right now.
After a job like that I wouldn't want to do much ether. Smiley

Want to try some fun? Yesterday I changed the fuel pump on a friends Volvo AWD in a parking lot in cold in wind. You have to remove rear seats and access plates under then to get to fuel pump in tank. But, to make matters worse the AWD tank is one piece tank split into two chambers connected with a runner over rear drive shaft and pump and sending unit installs on one side and then you have to fish a remote pickup for pump to other side which also has its own sending unit. (so you get to play in gas with hands in cold too.  Top that off with a bastard 4 inch plastic nut that holds units in that needs a special wrench. Fixing a floorboard by comparison would be a piece of cake. 

Glad you got it done, the only car I ever owned was a Mopar (77 dodge charger) Like that Valvo they are a little different. Smiley


I spent yesterday reassembling the resolution bandwidth / span width switch in my HP-8569B spectrum analyzer.
Broken contacts needed repaired. The rotary switch is made from an etched circuit board with the pattern of the stationary contacts, the rotor is a plastic disk with metal contact fingers hot staked to the plastic rotor. The contacts fall due to fatigue after about 25 years. Lots of small pieces and everything has to be clocked right for both switches to work, they are driven off a common shaft that can be disengaged to allow each control to work independently.
The hard one is next, that being the course and fine IF gain control which shares a shaft with the input atten....

The last time I did one of these (last year) rebuilding the IF gain / input atten. control stack took four tries to get it right ... I didn't have the rotors and their coupling hubs clocked right. This time I shall make lots of witness marks, and take even more photographs.

When I am not rehabbing amateur radio boat anchors, I am rehabbing HP and Tek Iron. Smiley

Won't be doing ether for a while, I injured my wrist yesterday wrangling an 8569 parts queen...

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Take Care
Sue,
AF6LJ

Don't Kalifornicate My Life
W8JX
Member

Posts: 13268




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« Reply #37 on: February 04, 2018, 10:55:31 AM »


When I am not rehabbing amateur radio boat anchors, I am rehabbing HP and Tek Iron. Smiley


I used to repair rigs for others some times ago but do not anymore. I sometimes struggle to keep up with own needs. (motivation)
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Ham since 1969....  Old School 20wpm REAL Extra Class..
AF6LJ
Member

Posts: 582




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« Reply #38 on: February 04, 2018, 11:34:36 AM »


When I am not rehabbing amateur radio boat anchors, I am rehabbing HP and Tek Iron. Smiley


I used to repair rigs for others some times ago but do not anymore. I sometimes struggle to keep up with own needs. (motivation)
I understand; sometimes a long walk in the woods is a better alternative.
I still enjoy it a lot though, been into electronics as a hobby since about 1968, a job from 1972-1994...
Always a hobby and my first love.
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Take Care
Sue,
AF6LJ

Don't Kalifornicate My Life
K9AXN
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Posts: 442


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« Reply #39 on: February 04, 2018, 11:52:43 AM »


When I am not rehabbing amateur radio boat anchors, I am rehabbing HP and Tek Iron. Smiley


I used to repair rigs for others some times ago but do not anymore. I sometimes struggle to keep up with own needs. (motivation)
I understand; sometimes a long walk in the woods is a better alternative.
I still enjoy it a lot though, been into electronics as a hobby since about 1968, a job from 1972-1994...
Always a hobby and my first love.

Sue,

The HP 8568B is one of the most used instruments on the bench here.  A real tribute to a time when excellence was a way of life.

Regards Jim
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AF6LJ
Member

Posts: 582




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« Reply #40 on: February 05, 2018, 11:49:06 AM »


When I am not rehabbing amateur radio boat anchors, I am rehabbing HP and Tek Iron. Smiley


I used to repair rigs for others some times ago but do not anymore. I sometimes struggle to keep up with own needs. (motivation)
I understand; sometimes a long walk in the woods is a better alternative.
I still enjoy it a lot though, been into electronics as a hobby since about 1968, a job from 1972-1994...
Always a hobby and my first love.

Sue,

The HP 8568B is one of the most used instruments on the bench here.  A real tribute to a time when excellence was a way of life.

Regards Jim
Indeed...
To many who pride themselves in repairing test gear this falls in the intimidating category.

65 LBS of love. Smiley
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Take Care
Sue,
AF6LJ

Don't Kalifornicate My Life
KM4AH
Member

Posts: 955




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« Reply #41 on: February 05, 2018, 01:50:48 PM »

I will. Just finished putting a floor pan in my 81 F150. Worn out right now.
After a job like that I wouldn't want to do much ether. Smiley

Want to try some fun? Yesterday I changed the fuel pump on a friends Volvo AWD in a parking lot in cold in wind. You have to remove rear seats and access plates under then to get to fuel pump in tank. But, to make matters worse the AWD tank is one piece tank split into two chambers connected with a runner over rear drive shaft and pump and sending unit installs on one side and then you have to fish a remote pickup for pump to other side which also has its own sending unit. (so you get to play in gas with hands in cold too.  Top that off with a bastard 4 inch plastic nut that holds units in that needs a special wrench. Fixing a floorboard by comparison would be a piece of cake. 


My own stupidity I admit. But, I frost bit my thumb and index finger cutting out the old pan with a die grinder. Had a pair of gloves on the bench. Sore as the dickens for a couple of days. So, not so much sympathy for your cold hands.
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W8JX
Member

Posts: 13268




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« Reply #42 on: February 06, 2018, 05:05:48 AM »

My own stupidity I admit. But, I frost bit my thumb and index finger cutting out the old pan with a die grinder. Had a pair of gloves on the bench. Sore as the dickens for a couple of days. So, not so much sympathy for your cold hands.

I have repaired several floorboards in my life time. I do not use metal though. I remove loose rusted metal and then I sandwich the damage area between fiberglass mats. (mat has random weave pattern vs fiber glass cloth and it molds and bonds better for this kind of repair)  If a support is needed due to a large hole to can use a board covered with a garbage bag to support it as it can be removed when it sets up. I also drill 3/8 inch holes through good metal around repaired area so that mat coated with fiberglass resin can bond through holes and make reliable patch. You can use fiberglass resin with a cheap throw away paint brush to apply it or fiber glass gel wit a nylon putty knife that it it easy to remove hardened gel from.When finished I coat underside of repair with spray on undercoat.  Never had to redo a repair and patch itself is rust proof.   
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--------------------------------------
Ham since 1969....  Old School 20wpm REAL Extra Class..
KM4AH
Member

Posts: 955




Ignore
« Reply #43 on: February 06, 2018, 10:13:08 AM »

My own stupidity I admit. But, I frost bit my thumb and index finger cutting out the old pan with a die grinder. Had a pair of gloves on the bench. Sore as the dickens for a couple of days. So, not so much sympathy for your cold hands.

I have repaired several floorboards in my life time. I do not use metal though. I remove loose rusted metal and then I sandwich the damage area between fiberglass mats. (mat has random weave pattern vs fiber glass cloth and it molds and bonds better for this kind of repair)  If a support is needed due to a large hole to can use a board covered with a garbage bag to support it as it can be removed when it sets up. I also drill 3/8 inch holes through good metal around repaired area so that mat coated with fiberglass resin can bond through holes and make reliable patch. You can use fiberglass resin with a cheap throw away paint brush to apply it or fiber glass gel wit a nylon putty knife that it it easy to remove hardened gel from.When finished I coat underside of repair with spray on undercoat.  Never had to redo a repair and patch itself is rust proof.  


Yeah, I thought about that. I have a roll of 1708 and maybe a gallon of West Systems 105 left over from rebuilding a 1960 Glasspar G3 . Plus a big bag of cabosil.

But, I just bought a pan from LMC and went that way.
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KH2BR
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Posts: 15




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« Reply #44 on: February 11, 2018, 10:59:34 PM »

When we get older, we take shortcuts and at times miss simple things while working/ troubleshooting circuits.
One big one that got me a couple of times is that I could not measure voltage in a circuit, and started tracing backwards and found I did not have power hooked up to the circuit even though the power supply was turned on.
Another problem is changing out parts and finding out the load was wrong.
I just bet a dummy load was not used to isolate the antenna system. I also expect the use of a  antenna analyzer was overlooked.
Changing out parts needlessly is a bummer if you overlook the obvious. 
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