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I had a sort of similar situation. I needed to regulate a high voltage for a tube rig. The PS that I had delivered 325V and I needed 275. I put a zener diode across the pass transistor to guarantee

It was a very warm day in 4 land today, so I finished painting the MS-4 cabinet. It's not "perfect" but it looks a lot better than what it did. I'm going to leave it as is.? I used Krylon 5557 satin

It is the boost voltage for the VCO so it is pretty low current. It runs one op amp that drives the tuning voltage to the varactors. Total capacitance between the 78L24 and the op amp is 3x 1uF, with

Jim, Given the high input voltage, voltage spikes are certainly a possibility, but I would also investigate how hot the device is running. High device temps accelerate failure rates. If I remember

Looking for Crystals? 23.5 mhz? ?and? 25.5 Regards KB9ASU

Hi Richard, Thanks. I worked on the T-4X earlier and was able to adjust front trimmers. With 1 volt at the injection connector, I have around 1.8 volts at the test point on all bands. The next step of

One of my TR7s suffered a 24V regulator failure yesterday. It was just sitting there running and failed overnight. Anecdotal evidence suggests that the 78L24 is a high failure rate part and in my

No, you do not have to remove the power connectors to take the covers of the RF deck. You DO have to take the bottom cover off the L4-PS and disconnect the line cord to remove the top cover of the PS,

Sounds like a relay contact problem. Steve Wedge, W1ES/4 Time flies like an arrow. Fruit flies like a banana. Sent from [Proton Mail](https://proton.me/mail/home) for iOS

Just two quick comments. Sometimes it helps to use a thin screwdriver to ease the covers off of the RF deck. ?Slight pry on the front area, then the rear, and back and forth. ?Then pry the sides

You can get the filter caps for your TR4C from Hayseed Hamfest. Can Capacitors and Re-cap Kits for Drake – HAYSEED HAMFEST LLC ( https://hayseedhamfest.com/collections/drake ) 73's, Mark, WB0IQK

Why not just replace the movement?

I have not had my cover off in a long time but seem to think that there are tabs so that you have to remove the power connector before the covers can be removed.? Probably a safety device to make

Hello to everyone in the group, I am looking for a plate meter for my Drake TR-4. Let me know if anyone has one to sell. Kevin M— W2AQY

Yes, I have. But that wasn't the OP's question. 73 -Jim NU0C "Jerry Kessler" <N4JL.cw@...> wrote:

Not to the order of removal. My experience has been that the tabs cause binding unless the opposite cover is loosened. Jim - have you noticed that? Jerry, N4JL Get Outlook for

Yes there are tabs that align the edges of the two covers. But they are not relevant to order of removal. 73 -Jim NU0C "Jerry Kessler" <N4JL.cw@...> wrote:

It's been a while since I've had my L-4B apart but isn't there a tab on at least one corner of the cabinet (top or bottom) similar to a TR-4 cabinet where in order to remove the top cover it helps to

The rotor is connected to a terminal which faces pretty much straight out of the bottom of the switch. Look carefully with the power off, its not hard to find. You need to do this in two places, both

That's OK, they have schools for that now. :D But seriously, all of us have to go back ad RTFM again often enough. Most people don't know this but I keep a PDF copy of the TR7 service manual open on