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Not as simple as I thought. Preparing to connect 2 Heathkit 54-30transformers: Single Pri/Sec windings for 110v to 1800v at 400mA with a CT. I need more plate current. The 54-30's are potted with no markings regarding phase (direction of windings around core), I don't have an oscilloscope but...

Assembled: $255. https://newdiytech.com/products/atu-atu-1000w-antenna-tuner Kit form: $150 https://newdiytech.com/products/atu-1000-atu1000-atu-1kw-atu1000w-automatic-antenna-tuner-7x7-atu-1000w-by-n7ddc-diy-kit Based on N7DDC Auto ATU board I've never used an Auto ATU but the price has...

Will this this 12A IDEC relay survive being connected to the Tune cap? I've seen longer Tune leads on factory amps. Tune cap is a 2-section affair where 2nd section only for 80-40. I need a way to switch the second section in & out. Tune cap is a punishing location but the lead lengths are...

I've been using a Dentron T-Match that's inefficient and it's increasingly noticeable. It appears that an L-Network is more efficient and very do-able using the same Dentron case. So it prompts the question, 'Why Dentron or other manufacturers always made T-Matches instead of L's given the...

I’ve had the bottom sealed up for a few days now so it’s starting to look reliable, fingers crossed. Marking the Load cap and Roller settings for 10 - 15 - 40 & 80 so there’s less tuning guesswork (picture). Little more than half a turn of Roller causes serious decrease in output from...

My 2nd post on this, I deleted the first, poorly written late at night. I'm chasing my tail lately on Tetrode project. It stopped amplifying despite correct voltages at tube pins and a reasonable zsac but in retrospect (below) I recognize the bias voltage was nowhere close to datasheet values...

I'm so tempted it's cross town so pick-up no problem. https://www.ebay.com/itm/395045335841?mkcid=1&mkrid=711-53200-19255-0&siteid=0&customid=link&campid=5336136228&toolid=20001&mkevt=1

Entire tower rotates.

I intended to replace a 1/2w BZX79-12 (NXP Semiconductor) with a 1N4742 generic (1w). They are both 12v. I've never seen the term Voltage Regulator Diode before. Datasheets seem similar but the diagram is not exactly the same. The BZX79 series are just Zener diodes, right?

Purchased a NOS CRL switch that required over a month of search & wait to find. There are so many CRL products sold online I assumed there must be datasheets somewhere. Radio Museum website reports the last company event was the purchase by Philips. It's hard to believe the company is Kaput...

Relays have occupied my recent free time. After seeing how slow it is for 1 relay to control another and maybe even a 3rd relay, I had to do something. In my online wanderings I found that in the case of NO, DC-coil relays that carry significant voltage or current, the opening is more of a...

I could not find and/or decipher the coil current requirement for this common 24v, Soviet relay. (datasheet in Russian). It's sold by several online vendors for as little as $30 plus shipping (>$10). The relay base is common to several configurations (SPST SPDT, etc). I found that the relay...

I have no experience with Vacuum switches. The Magnecraft reed-relay (SPST) I had between HVPS and plate choke began to stick. Thankfully, a safety habit of 'discharge before touching' paid off with only a frightful bang! Autopsy to look inside relay: 2 flat metal strips in a glass tube...

Fine tuning homebrew grid-driven 2x 4cx300 amp. Plate current meter is accurate now :rolleyes:. Specified ZSAC for plate voltage 1500 and up is 100mA. With 2 tubes I should see 200mA. Bias voltage adjustment can reduce zsac by raising bias voltage for a zsac of 230mA which is still too high...

Amp seems happier with the FW bridge (instead of doubler) and new tranny (Heathkit 54-30 1800vac @ 400mA). Amp still on worktable and I must close it up & move it to operating location for more testing. Noticeably lighter without the 16A filament winding despite having 6 separate transformers...

My 4cx300 tubes are starved for plate current. After years of working on this, I may as well do it right. I'm replacing the entire HVPS. Voltage Doubler replaced with a FWB driven by a different transformer rated for 1800v @ 400mA (Heathkit 54-30). No more combo trannies so I also ordered a 6v...

Been winding Baluns, tidying messy wires & tweaking this & that. Replaced the small core with 1-1/8" core (still mix 43). I'm focused on the RF Input section now. Changes take time to try and what works on a DL is not always good on an antenna. The attached "now" pic file is a diagram of...

PRESS FIT PTFE INSULATED FEED-THRU TERMINALS on eBay at https://www.ebay.com/itm/363996444302?mkcid=1&mkrid=711-53200-19255-0&siteid=0&customid=link&campid=5336136228&toolid=20001&mkevt=1 20 for $13 including delivery. Cambion brand with datasheet. .22" insert diameter. Several Sellers. The...

Interesting Homebrew at: https://www.ebay.com/itm/334888084436?mkcid=1&mkrid=711-53200-19255-0&siteid=0&customid=link&campid=5336136228&toolid=20001&mkevt=1 The base amplifier here is an “ST” DB-2933-54 test bed for it’s RF POWER amplifier using 2 x SD2933 N-Channel enhancement-mode lateral...