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The lowest Tune capacitance I can apply with an Air Variable is about 15pF. That minimum Tune C reduces PO by nearly 80%. Yet, with no Tune C connected at all (L network Tank) I see about 1:100 PO w/ reduced plate volts/mA. The RF Input parallel resonance revisions appear to work fine...

I assumed that the 750R RF swamping resistance was reduced by the .01uF bypass cap so it's closer to 450. I'm considering dividing one of the 1.5k resistors (the 2nd one after the trifilar on the way to band switch/tube grid) into 1.2k and 300. The 300 would be in series on the way to the grid...

OK I have some reading to do. I briefly saw that t match can also aid impedance matching. Is it feasible to use the pride’s swamping resistance of 750R as one of the T-pad’s resistance values? It’s already there

My FT891 only goes down to 5 watts and shuts off if I lower the VDC below 12v. A series resistor sounds like trouble. How far can I reduce the 750 ohms 'swamping' resistance to ground without altering the input impedance a'la Pride formula? It would make tuning & trouble-shooting easier if I...

The picture (above) of an external roller looks absurd and was a last resort. Fortunately, I don't need to pursue that route b/c the fixed inductors are working. It was the T-R relay compartment that precluded 10-20 meter operation (when reassembled). I did sample the input swr with the...

I was too fast to conclude total success. There was overall improvement but the same general pattern of too much C in pi network for 10-20 meters remains. This picture is an abomination but I’m hoping to rule-out inductance as an impediment to 10-20 meters. The last round of testing showed...

11M test just now showed over 400w AM from a 1970's 23 ch CB barely powered by a 12v, 2 amp bench supply. Amp still on work table so I was only using one plate transformer (1800 400mA). That's a best ever for 27Mhz especially given I did not even tweak Tune, Load or RF Input, just took a good...

Regarding the plate choke (thanks again Nomad) I compared with my old choke and found that it was roughly twice the inductance of W8JI's component so I'm hopeful that I'll see improvement. Over the past 2 months I replaced the point to point wiring of the RF Input I had strewn about the tube...

Found these handy screw terminals on ebay. They fit snugly and the metal is strong. Seller wants $3-4 for 7 of them. The screws are fine thread. https://www.ebay.com/itm/181677244055?mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5336136228&customid=&toolid=10001&mkevt=1

M162 LC R meter kit

Pictures and a hearty discussion of circuit

When it rains it pours. Thank you Nomad, came today in the USPS.

Thank you. Sounds like a good focus. I already began rebuilding the Input section and re-wound another choke. I'm waiting on some parts including a better LCR meter. I went with M-162 LCR kit ($40) only thru-hole components need be assembled. 40/80 no problem but I cannot see where I am...

Wire looks like 24-26? Reviewing my options: re-wind or get another. Uncertain what choke goes with 2 4cx300 tubes. When the attached picture is enlarged, a bulbous glob of copper is evident on each end of the wire break. Like a melted fuse. Choke went during 200w cw tuning with 4w...

I abandoned the mast-mount preamp effort. The swr bump wasn't worth the small gain on Receive and signal noise. Plus, it would have been another set of relay contacts exposed to elements despite being inside plastic case. The affects from condensation during the few years the old relay was...

I neglected to note that the 2:1 antenna relay board works good. Far better than the large latching relay I was using. SWR nearly flat. I do not like that a relay coil stays energized all the time during use. Latching was a failsafe as 1 antenna would always be connected even when power was...

It was only 1 bad relay and never had a bad relay coil problem ever, that I can remember. My estimation of the total number of relays I purchased over my lifetime is somewhere 40-ish. Yet I learned something else about the factory relays mounted on the Preamp board. Specifically, the...

This is what I found inside. The failure was it would not do anything when coil powered. It worked last night but today when I tested prior to taking to roof, it would not activate. Rated at 8A Can see color diff btwn the 2. The dark one I know is genuine. Light colored 1 I got from PRC

I've never had any brand of these small relays fail, today was the first time. It failed days after it was installed and the only usage was testing. Never left bench. It was one of 4, I purchased on eBay from China. I had a 6v version of same relay and I installed it temp basis. I know the 6v...

Using this to replace old large latching relay flattened my swrs on both antennas.