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Author Topic: KNIGHT T-175 INFO?  (Read 6833 times)
W4KVW
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Posts: 501




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« on: June 26, 2013, 08:14:19 AM »

I have a KNIGHT T-175 10/6 meter amplifier & can not find any information about the two coils that came with the kit.It has a coil installed but I'm not sure which band it is? It has 9 turns but the manual does not say how many turns is in what coil & I do not have the other coil since this amp was built already when I purchased it.Does anyone know how many turns should be in the 6 meter coil? I don't need any comments about this being a CB amp & a piece of crap from the trolls who frequent this site & others,just the info I requested.I will be using the amp with an old Hallicrafters HR-46 6 meter AM rig just to boost the power up a bit.Thanks for any assistance with this info & God bless! {:>)   Grin   Smiley

Clayton
W4KVW
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K8AXW
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« Reply #1 on: June 26, 2013, 08:45:15 AM »

Clayton:  I've never heard of the Knight T-175 amplifier but if it came with two coils, the one with the smallest number of turns would be the 6 meter coil.

Here is a link where you can plug in the dimensions and turns of each of your coils and see what the inductance is.

http://www.daycounter.com/Calculators/Air-Core-Inductor-Calculator.phtml

The higher the frequency, the less inductance needed to resonate.  6 meters is higher in frequency than 10 meters.

I'm not insulting your intelligence.... just giving you information.
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AA4PB
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« Reply #2 on: June 26, 2013, 09:29:27 AM »

If you could borrow a grid dip meter you could see where the coil is resonant. It would also be handy in cutting down the 10M coil to resonate on 6M. The part number for the 6M coil is M152-172 if it happens to be stamped on the coil anywhere (unlikely). I expect the majority of those amps were built with the 10M coil installed.
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W4KVW
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« Reply #3 on: June 26, 2013, 11:45:01 AM »

The coil that is in it appears HOME MADE because it was made with insulated wire & I do not have the other coil to compare this one to. Thanks for the quick responses.I'll keep looking for more information. {:>)   Grin

Clayton
W4KVW
EM80
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K8AXW
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« Reply #4 on: June 27, 2013, 08:37:33 AM »

Quote
can not find any information about the two coils that came with the kit

Clayton:  Sorry for the misunderstanding..... sometimes there's two ways of reading a statement.

PB has the best and fastest way to answer your question.  
« Last Edit: June 27, 2013, 08:40:06 AM by K8AXW » Logged
N2LXM
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Posts: 74




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« Reply #5 on: June 27, 2013, 08:43:24 AM »

Here is a link to the B.A.M.A. site that has the manul. It should be able to help you. But the grid dip meter idea is a good one to start with.

http://bama.edebris.com/manuals/knight/
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KD0REQ
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« Reply #6 on: June 27, 2013, 08:51:04 AM »

home made, eh?  optimized for 11 meters, I expect.
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KE3WD
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« Reply #7 on: June 27, 2013, 09:06:52 AM »

The coil that is in it appears HOME MADE because it was made with insulated wire & I do not have the other coil to compare this one to. Thanks for the quick responses.I'll keep looking for more information. {:>)   Grin

Clayton
W4KVW
EM80

Exciter-->Amp-->Dummy Load  and attempt to tune up on each band at reduced power, should sort it out rather quickly. 

And, if 6 and 10 don't tune, try 11...


73
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W4KVW
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« Reply #8 on: June 27, 2013, 09:28:52 AM »

I purchased from a LIAR at Dayton Hamvention who said it has the 10 meter coil in it & went into great detail about how great it worked on 10 meters just a week before Dayton.Not possible since the relay does not work without keying the rig then closing the relay manually every time it's keyed.I have the manual & it is NO HELP at all since it only mentions that it comes with TWO coils & the smallest one is for 6 meters.If I had BOTH it would be easy.I'll see if any of the locals have a grid dip meter & go from there.Thanks! {:>)

Clayton
W4KVW
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KE3WD
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« Reply #9 on: June 27, 2013, 12:47:34 PM »

The keying, if from RF sensing, would key on any RF within those limits anyway. 

It may be that the key sensing circuit has a fault.  Blown transistor, bad diode or cap. 


73
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W4KVW
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« Reply #10 on: June 28, 2013, 09:07:22 AM »

The keying, if from RF sensing, would key on any RF within those limits anyway. 

It may be that the key sensing circuit has a fault.  Blown transistor, bad diode or cap. 


73

Those all check out OK relay is bad for sure! Thanks!

Clayton
W4KVW
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WA3UTC
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« Reply #11 on: July 16, 2013, 10:27:56 AM »

The Knight Kit T-175 coil for 6 meters is 6 turns of #10 copper wire.  The coil for 10/11 meters is 9 turns.   I just completed a full re-build of a T-175.   Also note that the electrolytic can C-21a and C-21b in the power supply, if it is the original capacitor may be leaky as well as the other electrolytic’ s.  These cans are still available in in 40MFD/40MFD/40MFD at 450VDC, this is a three section capacitor, just use 2 of the sections.

Finding the 2 other C-19 and C20, 40MFD 450VDC electrolytic’ s is difficult, however a 47MFD @450VDC will work just fine in the power supply.   There are 3 other electrolytic’ s that should also be replaced and they are C16, C17 and C18.  They are 200MFD at 25VDC. 

Also note if you provide more than 4 Watts drive to the amp it will be over driven, hence use a 50 or 51 Ohm resistor as indicated in the drawing.  I would opt for a 10 watt resistor if you can find one. 

The amp is RF sensed with a sample of the incoming RF passed to V1 via a small sampling circuit.  Also note if you are using this amplifier on 6 meter AM to following the tune-up instructions in the manual or the amplifier will not be in linear operation.

Charlie, WA3UTC
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WA3UTC
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« Reply #12 on: July 16, 2013, 10:31:15 AM »

Forgot one thing about the 6 meter 6 turn coil.  It is wound on a 3/4 inch form, hence the inside diameter is 3/4 of an inch.

Charlie, WA3UTC
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KE3WD
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« Reply #13 on: July 16, 2013, 02:32:57 PM »

Hi Charlie,

Isn't it amazing how many hams nowadays want to be able to purchase a darn coil of wire rather than learn the simple arithmetic of rolling their own?  AND - the internet is chock full of automated calculators that make it so easy it ain't funny. 

Well, this fellow's problem turned out not to be the coil anyway, it appears that the RF sensing relay wasn't working.  He should also seriously consider bypassing that RF sense stuff and set the amp up to key from the rig...


73
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WA3UTC
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« Reply #14 on: August 19, 2013, 10:33:41 AM »

Clark:  Coils can be perplexing to some new folks if they have not been exposed to them.  Interesting enough that most tank coils for 6 meters are either 5 or 6 turns as you know.   Education is the key.

As far as the RF sense circuit it is a very simple diode detection circuit.  The problem with the one in the Knight kit T-175 is either low input drive or the input capacitor being out of spec, bad tube, bad relay or even leaky electrolytic’s. It is not necessarily the best RF sense circuit around.  Sonar in their 10 meter amps had a good circuit and it could be used in this amplifier easily; however I do prefer to use an simple keying buffer to key the amplifier.  I have built a couple of these boards and use them in amplifiers I re-build for folks and even in the KK1L antenna switches I build.  I have had great success with them.

Some folks also forget that with this amplifier if you have an input greater than 4 watts input a swamping resistor is required, or the amplifier will not be linear in operation, they sound like crap when they are non-linear.  The next thing with this amplifier is its duty cycle…..  100% key down for 20 minutes means looking for a new set of finals and they are not cheap, hehehe.  Cooling is another issue with this amplifier.   The stock fan just does not cut the mustard,  the amplifier needs at least three times the CFM of the current fan in order to keep the tubes cool enough.  These amplifiers are very good candidates for re-build for 6 meter AM,  see you on 50.400

73’s Charlie,  WA3UTC
 
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