Re: L7 makes alot of smoke
Bob,
Thanks for the added info. ?When you said the amplifier went dead I thought all power to the RF deck was lost thus the filaments were not illuminated, meter lights out, status indicators out, ?etc. ; that's why I thought the breakers might have tripped.
If one uses the B+ line as a reference, it seems like there are problems on the tube side as well as the RF output side. A parasitic/self oscillation could probably cause something like that, and possibly if the amp is operated as a doubler or tripler (e.g. if the bandswitch was in a band different than the exciter). ?Wonder ?if there is any damage to the RF safety choke across the output or if the bandswitch contacts were damaged.
In any case, I'm curious to learn from your inspections and recommendations of the experts on the Reflector. ?Please keep us posted, we'd all like to learn.
73,
Evan, K9SQG
On Friday, April 19, 2024 at 11:12:40 AM EDT, K6OXN Bob <bobk6oxn@...> wrote:
Both of the Parasitic Choke resistors were kind of burnt. That may be because of parasitics as C39 and 40 were the blown capacitors. I don't think the breakers blew as it seems when the caps went I lost HV. Haven't checked the PS to see if the .82 resistor blew, been cleaning up the area around the tubes.? All the RFC's look ok, no burn marks and check out with an ohm meter.? I have fully grounded grids as I did that not too long ago.? Resistance between grid and filaments check ok. Along with resistance between grid and plate. I really think some type of parasitic oscillation took place while on 15 meters.? I will carefully clean and replace those bad components and then bring it up gradually.
So much for trying to contact Easter Island as they were on strong last night at 221262.00. I could hear them very well about a 58 here and would have liked to have that contact.
73? Bob
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Re: Another TR7 Journey begins
I got the 3296P-1-103LF (10k ohms) and 3296P-1-102LF (1K ohms).?
They are horizontal adjust which puts the trimmer towards the top of
the radio.? Just a personal preference.? I haven't gotten around to
installing them yet.? Too many other projects. An R-4B to align, T4X
to figure out why it's not putting out any power now and a mini
lathe I'm upgrading with a longer bed.? Made time for some DX today
though. Chad on 2 new bands, 20 and 17 meters.
73
Stan
KM4HQE
On 4/19/24 15:14, Bill NZ0T wrote:
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Mouser:
5?3296Y-1-103
1?3296Y-1-102
73, Bill NZ0T
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Re: Another TR7 Journey begins
Operator preference. Use whatever way works best for you.
73
-Jim
NU0C
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Re: Another TR7 Journey begins
Thanks Eric I have that info saved and have to order sometime soon. Too many irons in the fire.
73, Jim VE1RB
Here is the thread about the multi turn pot in the TR&s.? Looks like there are some options.? I need to do this to my TR7 as well one of these day.??
/g/DRAKE-RADIO/topic/88447282#61251
73,
Eric
K8CCA
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Re: Another TR7 Journey begins
Mouser:
5?3296Y-1-103
1?3296Y-1-102
73, Bill NZ0T
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Re: Another TR7 Journey begins
Here is the thread about the multi turn pot in the TR&s.? Looks like there are some options.? I need to do this to my TR7 as well one of these day.?? /g/DRAKE-RADIO/topic/88447282#6125173, Eric K8CCA
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Re: Another TR7 Journey begins
Does anyone have a list of the pot values otherwise I will go look them all up. Also do you have the part number to buy either from Mouser or Digikey?
Thank you, 73, Jim VE1RB
Any other tricks I need to know?? Mount vertical or horizontal?? Horizontal seems better to me.
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Re: Another TR7 Journey begins
Any other tricks I need to know?? Mount vertical or horizontal?? Horizontal seems better to me.
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You, and all of us are in luck, Garry¡¯s wife is still providing the Drake service manuals.? Just visit K4OAH.com.? Garry used to also provide paper copies but now it¡¯s all downloaded.? I got a 2C manual from her a couple years ago. ? 73, Scott WA9WFA ?
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From: [email protected] < [email protected]> On Behalf Of Larry K3PEG via groups.io Sent: Friday, April 19, 2024 10:39 AM To: [email protected]Subject: [DRAKE-RADIO] 2-B info ? Hi,
I wanted to purchase the Drake 2-B info from K4OAH, but I found that he's an SK. RIP,? Garey.
Did anyone continue on supplying Garey's Drake rig information?
73,
Larry? K3PEG?
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Re: Another TR7 Journey begins
You will not regret it. When I do it I measure the existing pots so I can ballpark the new ones before I do the alignment. Makes it a bit easier. On Fri, 19 Apr 2024 08:55:26 -0700 "Bill NZ0T via groups.io" <nz0tham@...> wrote: I just ordered 10 turn pots for the power supply board from Mouser.? Seems that if I just look at the damn things they change so a bit over $35 shipped will be well worth it IMO.
73, Bill NZ0T -- 73 -Jim NU0C
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Re: L7 makes alot of smoke
Don't lose hope. They were loud on 10m a little while ago but working EU. I scored Chad for ATNO and two bands yesterday with someone else's L7. This one suffered a flashover in a Chinese 3-500z a couple of weeks ago. That is an event that I don't want to experience again... You would probably know if the safety resistor in the PS went. They go off like a M80 and leave shrapnel inside the PS. On Fri, 19 Apr 2024 08:12:38 -0700 "K6OXN Bob via groups.io" <bobk6oxn@...> wrote: So much for trying to contact Easter Island as they were on strong last night at 221262.00. I could hear them very well about a 58 here and would have liked to have that contact. -- 73 -Jim NU0C
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A golden screwdriver even less so. 73 -Jim NU0C On Fri, 19 Apr 2024 10:19:48 -0400 "Mike Bryce via groups.io" <prosolar@...> wrote: Must have been the same old tech that told me, ¡°A screwdriver will never fix a broken radio.¡±
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
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Yes his xyl still sells the files but not CD¡¯s. The info in his web site is good. Just send an email
73, Jim VE1RB
Hi,
I wanted to purchase the Drake 2-B info from K4OAH, but I found that he's an SK. RIP,? Garey.
Did anyone continue on supplying Garey's Drake rig information?
73,
Larry? K3PEG?
|
Re: Another TR7 Journey begins
I just ordered 10 turn pots for the power supply board from Mouser.? Seems that if I just look at the damn things they change so a bit over $35 shipped will be well worth it IMO.
73, Bill NZ0T
|
Hi,
I wanted to purchase the Drake 2-B info from K4OAH, but I found that he's an SK. RIP,? Garey.
Did anyone continue on supplying Garey's Drake rig information?
73,
Larry? K3PEG?
|
Re: L7 makes alot of smoke
Both of the Parasitic Choke resistors were kind of burnt. That may be because of parasitics as C39 and 40 were the blown capacitors. I don't think the breakers blew as it seems when the caps went I lost HV. Haven't checked the PS to see if the .82 resistor blew, been cleaning up the area around the tubes.? All the RFC's look ok, no burn marks and check out with an ohm meter.? I have fully grounded grids as I did that not too long ago.? Resistance between grid and filaments check ok. Along with resistance between grid and plate. I really think some type of parasitic oscillation took place while on 15 meters.? I will carefully clean and replace those bad components and then bring it up gradually.
So much for trying to contact Easter Island as they were on strong last night at 221262.00. I could hear them very well about a 58 here and would have liked to have that contact.
73? Bob
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Peter Thanks for the info, ok on it being for the RR1 RR2.?? Great picture of the LN4 in the RR1. Sure don't remember seeing anything like that. I was not that familiar?with their marine line products as much as their 4 line. Thanks Rex WB8TDG
You are the winner of this thread.
On Thu, 18 Apr 2024 19:53:57 +0000
"Steve Wedge, W1ES/4 via " <w1es=[email protected]> wrote:
> I'm going to go take a shower now...
>
>
>
> Steve Wedge, W1ES/4
--
73
-Jim
NU0C
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Must have been the same old tech that told me, ¡°A screwdriver will never fix a broken radio.¡±
Mike, WB8VGE
SunLight Energy Systems
The Heathkit Shop
J e e p
o|||||||o?
A man with one clock knows what time it?is. A man with two clocks is never sure.
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On Apr 18, 2024, at 11:10 PM, Jim Shorney < jimNU0C@...> wrote:
An old tech once told me that "it's almost never the alignment". If it is equally deaf on all bands you have a fault in the common parts. Follow the signal chain and see where you lose it. 73 -Jim NU0C On Thu, 18 Apr 2024 21:40:18 -0500 "Ed KG5UN via " < maikranze@...> wrote: The jumper made no difference. It appears this rig just is a little deaf.?
I am going to see if I can return it.?
Ed?
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Re: L7 makes alot of smoke
Bob,
Could you provide a few extra details?
Were all of the parasitic choke resistors "fried"? ?If so, that might be symptomatic of a self-oscillation or parasitic. ?. ?With the strapping as a DC path it is unlikely that they failed due to a B+ or tube problem.
If the entire amp went dead, then that means the circuit breakers probably tripped. ?
What two capacitors exploded?
73,
Evan, K9SQG
On Friday, April 19, 2024 at 12:47:40 AM EDT, K6OXN Bob <bobk6oxn@...> wrote:
Earlier this evening, while trying to tune my L7 up on 15 meters, there was a large flash and bang.? The L7 went dead and alot of smoke came out.? Opened it up and found the 47 ohm plate resistors fried and the 2? capacitors exploded. I have ordered a couple of new door knob caps and some resistors. Does anyone have any more ideas as too what else might be effected?? Much thanks in advance.
73? Bob
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Re: L7 makes alot of smoke
Sounds like a plate-grid short. Check the tubes for shorts. Check the plate choke to see if it opened. Look under the chassis and check the grid chokes.
In the power supply check the .82 ohm resistor as it will act as a fuse. Hopefully it didn't take out any rectifiers.
It could also be one of the plate caps shorted. Check RFC6.
Those are the most common failures but these events can be quite catastrophic so hopefully none of the metering got damaged.
--
73 de Mike, W1NR
THAT was the equation. EXISTENCE!... SURVIVAL... must cancel out... programming!
- Ruk -
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Jim Shorney
K8CCA