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 Post subject: Knightkit T-60 Transmitter Questions
PostPosted: Jun Sun 16, 2019 7:55 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
I'm going to have some questions about this Knightkit T-60, so please bear with me. My skills are limited to repair, not engineering or inovation. I've received this Xmitter as an unfinished modification project apparently, and I'm not sure what they were trying to achieve. Somebody has added a solenoid/relay and a BNC jack on the rear chassis. They also left the negative lead of the big capacitor unhooked. Rather than remove all these modifications and restoring it, I'd rather push on with the mod, IF it can lead to something useful. I've included attachments of what there is so far. Also here is a chart of what is connected where. The schematic isn't clear, because it is a screen shot. BAMA documents are passworded, so I wasn't able to open their PDF in Photoshop for a clear copy. I am including a link to the BAMA site in case you need to download the manual for a clearer view. It's the 3rd 14 mgb file. The schematic is on PDF Page 32. One more thing. Somebody has changed the oiginal RCA connector to some strange connector with a spring-loaded center contact.
The Solenoid: The relay contacts are in the "always up" position by default.
A) Blue wire, goes to center conductor of added BNC jack on back
B) Coil lug 1
C) Pin 2 accessory socket
D) Yellow wire, goes to center conductor PL259 antenna connector
E) Goes to nothing
F) Contact 2 on SW-2, out in standby position
G) Goes to nothing
H) Pin 8 accessory socket

http://bama.edebris.com/manuals/knight/t60/


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Solenoid copy.jpg
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mike connector.jpg
mike connector.jpg [ 191.78 KiB | Viewed 624 times ]
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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 1:22 am 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9908
Location: Santa Rosa, CA
The mod might be a muting relay to silence a receiver while transmitting.

Personally, I would take away all the mod items and return the T-60 to its original state. Of course, change the filter caps before firing up.

Rich


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 1:43 am 
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As Rich points out, it would probably be better to bring the rig back to its original unmodified state rather then trying to second guess what the previous owner was trying to do.
As far as the mike connection, previous owner probably had one of these connectors on his mike cable.

Image

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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 1:51 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
It's my nature to restore it to original also. But I want to find out what this is and if it's actually useful. After all, somebody has already drilled holes in the chassis and defaced it to some degree. If it's going to be useful, I might as well complete it and use it.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 2:15 am 
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I agree with Rich to take it back to stock to avoid problems. From your description, it sounds like the previous owner was installing an internal transmit/receive relay to switch the antenna between the transmitter and receiver.

Rodger WQ9E


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 2:30 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
You mean I spent 3 hours today on the computer preparing my little presentation, and all I hear is put it back to original? Any other time I'd be the first one to say that. But I'm not going to be happy till someone can tell me what I have here, and how to complete it. Then I'll decide whether to remove it. I've been studying a T/R switch from a 1961 QST magazine that uses a 6AH6 tube. That looks very interesting. But I still want to investigate what I have already on this sweet little Knight kit. Tonight I won Knight P-2 SWR meter for a bargain.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 1:59 pm 
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Joined: Apr Thu 12, 2007 3:24 am
Posts: 1991
Location: Milwaukee,WI
Maybe because it was a WIP the wiring makes no sense to me.
1. What possible reason could there be for contacts B and D to short together or open? The contacts are across a piece of wire, already shorted together. Useless.
2. The relay coil connections. One connection side to the AC power line and the other to the 6.3 volt filament secondary? Makes no sense to me.
3. Whatever type of power switching the previous owner was attempting to do might have been radio specific and of no use to you.
4. Without knowing where the 1st lead of the capacitor is connected there is no way to determine where to put the 2nd lead for sure.

I'm all for modding the radio as many others have done. But this hack job deserves to be undone. Get the radio back to original but leave the relay mounted in case you want to redo a mod according to a published article.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 2:54 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
Thanks
That last post opened my eyes. Up till now I had been tracking wires for the purpose of drawing up what I originally posted, without actually thinking anything through. But the above post is right. This is a boob jack job if ever I saw one. I'm taking out this whole mess and putting it back to original. But I do have other questions about other things, so please stay tuned.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 3:14 pm 
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Joined: Nov Sun 15, 2015 8:32 pm
Posts: 118
Location: Poteau, OK
henry finley wrote:
You mean I spent 3 hours today on the computer preparing my little presentation, and all I hear is put it back to original? Any other time I'd be the first one to say that. But I'm not going to be happy till someone can tell me what I have here, and how to complete it. Then I'll decide whether to remove it. I've been studying a T/R switch from a 1961 QST magazine that uses a 6AH6 tube. That looks very interesting. But I still want to investigate what I have already on this sweet little Knight kit. Tonight I won Knight P-2 SWR meter for a bargain.


You asked to know what the relay mod is and how it's connected.


The large connector on the front panel next to the CW key socket is the "Microphone" connector. This is
shown in the T60 manual. While this connector may not look the same as the original connector, it's
there to connect a microphone to. The T60 has AM mode that uses "CCSM" (Controlled Carrier
Screen Modulator) method for modulating the final amplifier's screen for AM. If you don't know what
CCSM is then go to page 26 in the T60 manual that explains how CCSM AM mode works. A member has
already shown you the microphone connector that will screw onto the mic connector on the front panel.
Those connectors can be found on eBay.

You didn't specify what the relay coil specifications are (typically stamped on the relay coil). Without
those specifications (make, model, coil voltage etc) I can't say how to wire the relay coil, to 120VAC or
to 6VAC. Also not knowing whether the relay coil is rated for AC or DC make a difference.

If your letter labeling is correct, there is at least one major Safety wiring error!!

Major wiring error!!
One terminal of the relay coil "C" is connected to "X" on the rear panel octal socket
pin 2 which connects to the power transformer's 6VAC filament secondary winding of
the power transformer. The other terminal of the relay coil "F" is connected to Function switch
tab "2" which connects to "120VAC". This will never work and will cause a short between one
lead of the transformer's primary winding of 120VAC and one lead of the transformer's secondary
winding of 6VAC when the Function switch is set to any position other than OFF.




The relay terminal letter "H" shows the N.C. relay terminal is connected to the rear panel octal socket
terminal "8" which has "120VAC" from the power transformer's primary winding. This will, with the
relay NOT energized, put 120VAC on relay terminal letter "E" which has a wire that's not connected
to anything.

The relay terminal letter "G" shows nothing connected so nothing to discuss here.

The relay terminal "A" provides a antenna connection to "D", most likely for a receiver
antenna connection. With the relay not energized, the antenna at "D" connects through
the relay terminal "A" to the newly added BNC connector on the rear panel (receiver antenna).

The relay terminal "B" appears to connect coil lug 1 to the rear panel SO-239 antenna
connector at "D" when the relay energizes. Provides a path for RF output to the antenna
with the relay energized.

Relay terminals "A" and "B" appear to provide a T/R relay switch with a receiver connected
to the newly added BNC connector on the rear panel.

Why the capacitor's negative lead is disconnected is unknown. Can't speculate why that lead
is disconnected since there's no indication where the positive lead is connected.

There is a major wiring error as stated in the beginning. Not knowing the relay specifications
it's difficult to determine whether to power the relay from 120VAC or 6VAC. Also the relay
specs will determine if the relay coil is AC or DC. Some relays will operate from a high AC
voltage or a low DC voltage. The relay part number and manufacturer plus coil voltage is
often stamped on the relay coil. You need to look for that information before proceeding.

_________________
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Mike W5RKL
https://www.w5rkl.com


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 3:50 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 13817
Location: S. Dartmouth MA 02748-1225 USA
henry finley wrote:
Thanks
That last post opened my eyes. Up till now I had been tracking wires for the purpose of drawing up what I originally posted, without actually thinking anything through. But the above post is right. This is a boob jack job if ever I saw one. I'm taking out this whole mess and putting it back to original. But I do have other questions about other things, so please stay tuned.
+1, 2 & 3!

I will tell you why...

Google [Knight T60 transmitter problems]. That search sums up what may go on with "unmodified" T60's.

My SK Ham friend had one, could not stop the final from going into VHF oscillation on its own above 20 meters. Ate 3 new finals before flipping it at a Ham flea...

A game changer will be the condition of the function and band switches. If these are burnt only a new one from another rig will fix or some sort of creative mod...

Clean the switch wafers and rotors with 91% alcohol only and dry thoroughly, NO contact lube as it will creep and leak to the shaft causing a B+ burnout...

It is my suspicion the relay was an in chassis installation of a T/R switch, nothing more. To take the wear and tear off of the function switch. It is not an "RF" rated relay, this addition to the tank circuit could cause a stability problem.

boob jack job The self/shorting/ closed circuit mic jack was to solve an RF feedback problem into the speech amp when using CW with no mic attached. I would leave that in place, very sensible change.

One may still need to transfer the antenna via an RF relay for station operation. Switch power for that would come from the accessory socket in the rear. Be aware that source may have some stray RF when key down, so some bypassing, use of shielded cable required.

SOP with this transmitter, the 6DQ6 cathode will shed oxide like a spray gun.Dip and load FAST! the oxide soon sheds to the control grid and the tube then takes off into VHF oscillation. Best advice is to have a good antenna ready and not experiment with SWR using the T60.

Post an image of the front panel. As restoration moves forward, certain sensible changes could make use of the holes.

BTW What is your call and QTH?

GL

Chas

WA1JFD

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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 4:50 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
Thanks. I'm KN4SMF, Charlotte. The main reason I think I was wanting to salvage this mess was to save the function switch from constant switching. But for now, I've already removed the solenoid and will be working on restoring the wiring back to original. Here are some photos of the extracted solenoid. As for antenna switching, I'm thinking making the little box I posted earlier from the 1961 QST article, and possibly eliminating the power supply and using the takeoff points from the transmitter socket. Except I wonder if Allied took into account when they designed the rig, the need to put in an over-sized power transformer, so as not to overload it at the accessory socket.
I will be asking other questions in this same thread, so as not to be continually making new threads.
Im concerned with the meter movement, as it has no provisions for zeroing and this radio came to me with the needle 1/4 inch to the right of zero. I suspect the meter may be bad therefor.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 6:03 pm 
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It was probably an attempt to use an open frame for an antenna change over relay. The BNC was most likely for the receiver antenna connection.

The relay would have followed the function switch going between standby and tune/transmit. Since it is a DPDT relay, one pole could be used for antenna, and the other pole for the receiver muting.

Two problems. The coil should have NEVER been connected to the plate tank! And, the correct relay would have a 155VAC coil at 60 Hz. Not a 6 volt coil!

A lot these were sold to inexperienced novice licenses back in the 50's and 60's. It is not uncommon to find hack modifications performed by hams who had little technical skill.

Pete

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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 6:38 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
Thanks for the help. Right now I'll be running the rig CW as I only have one 7037 kc crystal. But I have found a Knight vfo. A bit overpriced but they're a lot rarer than Heathkit. I'm including a link to the auction if anybody wants to put in their 2¢ worth. Otherwise I'll be keeping my eye out for a Heath VF-1. My preference for the Knight one is it has its own power supply and the Heath has to take off the transmitter, and I've heard that causes chirp. See link below:
https://www.ebay.com/itm/Vintage-KNIGHT ... %7Ciid%3A1


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Mon 17, 2019 9:23 pm 
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Joined: Nov Sun 15, 2015 8:32 pm
Posts: 118
Location: Poteau, OK
73 magazine ran an article on the T60 in their March 1962 issue. Their test shows the
T60 had an approximate RF output of 40 watts on 80 decreasing to approximately 13 watts
on 6 meters. At that low power level a 6 or 12 volt DC DPDT relay could handle the RF.
The article is available on my website by clicking the link below:

https://w5rkl.com/wp-content/uploads/2019/06/73-Mag-comments-on-T60.pdf

The relay in the mod appears to be a 6VAC 50-60 cycle DPDT. I have a similar new Potter & Brumfield
KY-11AY-6 6VAC 50-60 cycle DPDT relay. The coil's resistance is 7.2 ohms. With 6VAC applied
the current flowing in the coil is approximately 0.833 amps (833ma).

6 / 7.2 = 0.833 amps

I would not attempt to power that relay using the T60's power transformer's 6 volt filament winding,
you could easily exceed the 6 volt filament winding current rating.

A better T/R relay would be to use a 120VAC DPDT relay powered through the T60's rear
octal socket pins 7 and 8.

The meter is a "REL PWR" indicator, not a plate meter. I recommend using the low sensitivity
setting of the rear panel meter sensitivity switch. I burnt out the meter in my T60 back in
the 60s using the high sensitivity setting (higher meter indication). All that's needed is to see
a peak indication on the meter, whether using the high or low sensitivity setting.

CW keying, keys the cathode circuit of V1A Osc, V1B Multiplier and V4 final amp. The DC
voltage on the CW key will be rather high when the CW key is not pressed. This is typical
for Cathode keying.

I have the T60 assembly manual and a better/clear schematic on my website in pdf format.
Click the links below to download them free

Schematic
https://w5rkl.com/wp-content/uploads/2019/06/T60-Schematic.pdf

Assembly manual
https://w5rkl.com/wp-content/uploads/2019/06/T60-Assembly-Manual.pdf

Good luck with the T60.

_________________
73
Mike W5RKL
https://www.w5rkl.com


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 12:36 am 
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Joined: Dec Sun 14, 2008 3:33 pm
Posts: 843
Location: Tokyo
Part of a long thread on the T60. Scroll down to W9BRD's comments on the design. Educational.

https://www.antiqueradios.com/forums/vi ... 8&start=40

Rob


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 1:40 am 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
Bit by bit I'm getting rid of this mess. This had to date back all the way to original building, as the wire routing, drilled holes, and solder joints could never be done to the finished radio in the manner they are. What a knucklehead mess.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 2:55 am 
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Location: S. Dartmouth MA 02748-1225 USA
shinkuukan wrote:
Part of a long thread on the T60. Scroll down to W9BRD's comments on the design. Educational.
https://www.antiqueradios.com/forums/vi ... 8&start=40
Rob
Yes, there is the answer to the T60 that frustrated me so 50YA. Designed by a committee... None the less there was some interesting factoids about the 807 (Knight T50).

Chas

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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 1:33 pm 
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Chas wrote:
shinkuukan wrote:
Part of a long thread on the T60. Scroll down to W9BRD's comments on the design. Educational.
viewtopic.php?f=5&t=180838&start=40
Rob
Yes, there is the answer to the T60 that frustrated me so 50YA. Designed by a committee... None the less there was some interesting factoids about the 807 (Knight T50).

Chas


The T50 is a solid little transmitter and not surprisingly since it is a nearly perfect copy of the Johnson Adventurer. The T-60 and T-150 can be tamed but they definitely aren't as clean or forgiving as the T50.

It is a good think Allied/Knight never actually produced the T-400 "expandable" transmitter because at the rate things were going downhill with design after the T50, the T-400 would have been a true disaster.

I prefer the Knight to the Heath VFO, I have a couple of them. If you buy a VF-1 (or HG-10) I would advise building a separate power supply for it because the T-60 supply is on the light side anyway and I wouldn't want to put any extra load on that transformer.

Rodger WQ9E


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 7:52 pm 
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Joined: Jul Sat 28, 2012 9:32 pm
Posts: 233
Well I got it together and tuned it up on a light bulb for the first time, with a key and crystal on 7037. The directions say to tune it with the function switch on tune, the switch over to cw and retune. But the 2 positions have totally different behavior. Further in the cw position, the load control buried the meter to the right as I turn it higher in the cw position. And another thing-- as I listen to the cw tone on my hallicrafters sx 110, the tone starts out at one pitch when I close the key, and goes higher pretty quickly. Is this chirp? I'm told to expect that with something like Heathkit VF1 with power takeoff from the transmitter. But I wasn't expecting it on a crystal. I wonder where to start looking in the transmitter to clean up the tone pitch. But all in all I was glad that I actually got it working.


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 Post subject: Re: Knightkit T-60 Transmitter Questions
PostPosted: Jun Tue 18, 2019 8:06 pm 
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The transmitter should behave differently between Tune and CW positions, Tune is a reduced power position for initial tuneup while CW allows full power which is why tuning must be done quickly. Power output will go up as loading is increased until loading is excessive at which point it will begin to drop. As loading is increased, the circuit is brought back into resonance with the plate tune control so you are alternating between both for proper tuneup for CW. If the loading is increased to the point that the peak with the plate tune control is broad and shallow, then loading is excessive and the load control should be slightly reduced and the plate re-tuned for peak.

This is easier with rigs that have a plate (or final cathode) current meter but it is doable with only an output meter like the T-60 provides.

Where did you get the crystal that you are using? It sounds a lot like one of the fake FT-243 crystals with a tiny crystal inside that will shift with initial heating. In a low power rig like the T-60 they will generally work OK for AM but not for CW where they create a constant chirp with keying. I have a couple of those for 3885 in my Ranger and Viking 500 and they shift a few hundred hertz every time they go into transmit.

Rodger WQ9E


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