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If you can get someone that has a NanoVNA H4 with the DSlord firmware in it to sweep the crystal you have you should have all of the information you need to change to the 55MHz crystal. There are some

Hi Bruce, Yes I saw your message, on ko4bb Thanks My 7603 scope is temporarily sick and waiting my attention so my 7L13 system is out of action Not sure if I will bother with this system anymore as

This is the link I failed to provide in my previous message http://www.ko4bb.com/doku2015/doku.php?id=test_equipment:tracking_generator_-_convert_tr-502_to_tr-503_configuration The major step is

The TR503 and likely TR502 crystals were supplied by Colorado Crystals.? They might be ale to provide the needed ordering information.? Some years back, they still had a few 55 MHz crystals left

Hi Nigel, Thanks for the reply I have a 7L13 but it is a toy compared to your 7L14 so I want to switch over to using my TEK 494 which requires a TR503 tracking generator. The tr502 and tr503 are

Firstly I'm curious as to the benefit of converting to a 503? I have a 502 & 7L14 and had to do some very tricky repairs in the 502 A120 assembly (and others); I had to remove and refit one silica

Hi All TEK lovers, I would like to try and convert a TR502 to a TR503 I understand that I need a 55Mhz crystal to replace the 52.5Mhz.The specs say its a series resonant quartz crystal , do I need to

EEVblog.com WTB forum, Ham radio fleas see ARRL.ORG for your local swap meet Jon

I need a pair of Tek 7K plugins.? I thought I would try here before going to the auction site. 7A12......I actually have a need for this specific amplifier type. (dual inverting) 7B53A w/Option

Hi Jason, I seem to recall that the filter capacitor for the -15V supply is almost always bad. It is one of the 180uf 40V caps. The -15V supply has as its principle load the EHT power supply that

--- R1292 should be adjusted for +10V at TP201. It will impact +5V regulation but it will impact other circuits as well. It is best to set it to 10V.

Low voltages and one of the 180 μf 40 volt caps was obviously bad. Probably the rest of them too. It seemed to come on fine in the scope. I checked voltages and 10 v was dead on, 87 v is 80.8, 42 v

Single 2-ohm 25W from J232 should be enough. The resistor network in the manual is for full load, PSU should function enough for debug with a single resistor. What issues do you see with the PSU (it

Okay. The manual was fairly clear, but I don't have a J303 on my ps board for some odd reason so that would have put all the draw on that one fuse, and might wind up blowing that fuse, so I was trying

Yes. Different manuals say different things. Anything that can dissipate the power, and is between 1 and 2 ohms, is fine. You can actually get away with less current (higher resistances). Switching

Hi Jason, Your understanding is correct. Ozan ===

Let me make sure I'm understanding this correctly. In the service manual it says to connect two 2 ohm 25 watt resistors, one to J232 and one to J303 and then to ground. In effect a 1 ohm 50 watt

I use 330uf 63V caps for either the 180uf 40V or the 250uf 25V that appear in the supply. I choose to use the higher voltage, rather than stick with the voltages tek used because the ESR is lower for

Thanks for the advice on the caps. I was wondering if I needed to stay with close to the same values or go with the 330μF recommendations across the board with those. So I CAN completely remove the

I'll agree not frequently.? Assuming about 40 to 50 pieces of powered equipment, most at least plugged in, one failure.? The simple numbers say 2%, the actual numbers, if I had more equipment,