OTB – Tektronix 453A

I picked up a broken Tektronix 453A scope from Craigslist. It had a few issues, however none of them were fatal for this unit. I initially checked the power supply voltages and they all seemed okay. After looking around a bit more and reading the service manual I found the primary sawtooth signal was basically … Read more

OTB – Old Yellowing Plastic

I was repairing an piece of older HP test gear, and the control buttons had all Yellowed with age and sun exposure to a large degree. So I pulled them all off the system, and tried the Hydrogen Peroxide + UV treatment. This process works great!  You need 40% (or greater) hydrogen peroxide, which you can … Read more

Tested – Realistic Navaho TRC-431 40 Channel CB

This 40 Channel CB radio has a very nice signal output is really clean after some elbow grease IPA and a zillion paper towels…. Power filter caps are good, power supply ripple is very low, and internals are very clean. Verified receive sensitivity and transmit THD all in spec. Checked with my spectrum analyzer, frequency counter, … Read more

OTB – Kenwood TR-9000

I picked up a TR-9000 from the Dayton a few years ago, It was a bit dirty and needed a little tune up. Worked for the most part, except the PLL was not locking until warmup. A detailed alignment exists for this radio and once followed all was well. It’a a nice 2M SSB radio, … Read more

OTB – HP 5216A 12.5 MHz Electronic Counter

I picked up an HP 5216A 12.5MHz Electronic Counter from a hamfest recently in Loveland CO. I figured it needed a lot of love, based on it’s condition at time of purchase.  After checking it out, found it had a totally fried resistor in the attenuator section and some very, very dirty switch contacts which … Read more

OTB – HP 3325A Sensitized Function Generator

On the Bench: HP 3325A Sensitized Function Generator. It had a completely sorted out bridge rectifier and a shorted transistor on the -15v rail. It is also had a broken power button, missing another button (Now on order) and was missing a “spring” on one of the buttons as well. Else, this tests out great … Read more

OTB – HP 5385A Frequency Counter

On the bench today┬áis a HP 5385A frequency counter which seems to have a short to ground on the 5+ rail. Someplace….. Hunting.   Fixed: The 5v over voltage crowbar protection circuit was being switched in, because the 5V rail became noisy/ripple (+/- 700mv ripple voltage). Replaced the aged smoothing capacitor on the 5v switch … Read more

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