#29 Vintage gear I picked up for future teardowns and restore videos - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 14, 2016, 02:51:58 am
content: In this video we take a quick look at some vintage ham radios and test gear a friend gave to me today. This is what we have:Kenwood TS-520 hybrid HF rigHeathkit DX-20 CW transmitterEico model 215 signal generatorHeathkit HP-23 power supplyHP model 410A Volt OHM meterI will used these in future repair and restore videos

author: AF6LJ
author_rank: Unknown
timestamp: February 15, 2016, 11:53:30 pm
content: In a Word Cool...

author: TimFox
author_rank: Super Contributor
timestamp: February 17, 2016, 09:35:02 pm
content: The only piece of equipment that I own that is older than me is an -hp- 410A voltmeter (on the left of your title still).I had to replace one capacitor (across the line) and clean up the sockets on the RF diode (2-01C).I replaced the 6SN7 dual triode, but it was not quite dead.After that, it was easy to calibrate the unit back to factory spec.I believe there were two options on the diode: mine used two 2-01C vacuum diodes, one in the probe and the other to balance out the DC offset, but the manual I found showed a solid-state diode in place of the balancing unit.Note that the DC input resistance is 110 Megohm, with 10 Megohm in the probe. Normal VTVMs of that era had 11 and 1 Megohm, respectively.I took a vacation cruise with many people my age a few years ago. At dinner one night, the husband of the other couple at the table said he had retired from -hp- and I mentioned the 410A. By coincidence, his first job at -hp- was to write the manual for the 410B.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 17, 2016, 10:15:05 pm
content: Quote from: AF6LJ on February 15, 2016, 11:53:30 pmGood word

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 17, 2016, 10:19:02 pm
content: Quote from: TimFox on February 17, 2016, 09:35:02 pmThanks for that story. Sounds that it was great to meet the guy that wrote the manual.As far as the 2 diodes mine has both. I slid the cover off the unit last night. Cover is going into the media blaster this weekend due to large amount of surface rust. on it. Inside looked fairly decent. I will take pics before doing anything and add them to the tear down/restore video. Going to have to replace the probe leads. AC lead is very stiff, common lead is cracking up.

author: TimFox
author_rank: Super Contributor
timestamp: February 19, 2016, 07:22:23 pm
content: I also had to replace all of the unshielded test lead wires due to bad cracking.I rescued my unit from a dumpster during my university days.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: February 19, 2016, 07:39:53 pm
content: Quote from: TimFox on February 19, 2016, 07:22:23 pmAnother one savedThose leads really get in bad shape after all these years

author: AF6LJ
author_rank: Unknown
timestamp: February 21, 2016, 01:26:05 pm
content: Quote from: Radio Tech on February 17, 2016, 10:15:05 pmOne of my favorite words....

author: AF6LJ
author_rank: Unknown
timestamp: February 21, 2016, 01:28:50 pm
content: Quote from: TimFox on February 17, 2016, 09:35:02 pmThe college I went to had a couple of those in their electronics lab, I can remember drooling all over myself dreaming of the day when I would own one of those.I have a well cared for HP-412 VTVM that works like a bomb.