The way to make 6146's sound good as modulators is to run them in a triode connection: control grids grounded; feed audio to the screens w/screens @ DC ground. Takes more driving power, but the results are well worth it. For plate supply over ~750V you may need to put a few volts of negative bias on the control grids (still @ ground for audio, tho.)
73, -Larry/NE1S Brett Gazdzinski wrote: > > Steve, N2DXM had one of these about 20 years ago when > we both got into AM. > A nice transmitter, well made, but poor choice of modulator > tubes, 6146's I think they were. > I never got a pair of 6146 tubes to sound good as > modulators, but I suspect some people have. > A prime candidate to switch to KT88 or KT90 tubes in > AB1. > > My top pick for a 100 watt transmitter is the 32v2 or 32v3. > Robust iron, good stock sound, very stable pto, reliable > operation. > I have had 2 for 15 years now (sold the third for $200.00) > and never had a single problem with any of them, despite > using them a lot. > I am using them for exciters now, to drive the homebrew rigs. > > I run mine on high voltage with solid state diodes in the low > and high voltage power supplies, no problems at all. > > No grid tuning or drive levels to fool with, tune the vfo > to frequency, dip and load the final, and yak.... > > There is not much that HAS to be done to the stock rig > to make it sound very good, just a resistor change > to match a d104 better... > > Ask anyone who has had a number of 100 watt rigs including > the 32v3, and most likely they will tell you they like the 32v > best. > I have got rid of all the others, but kept the 32v's. > > The only Collins stuff I really like is the 30k-1, the 32v series, > and maybe the kw1 (never had one of those). > Did not like the kws1, kwm2a, 75a4, r388, etc. > > Brett > N2DTS > > > > > I just finished cleaning up the B&W 5100 I picked up > > at the Butler meet last Summer. > > > > I don't know what prompted me to buy it , but now I am > > sure glad I did. Maybe it was all the great food ( > > including Russ's fabulous baked beans of mass > > destruction HI!) > > > > What strikes me the most about this radio is how well > > it is designed and constructed. My only complaint > > about the design is that the mode switch intereferes > > with access to one of the audio input shield screws - > > boo hoo. > > > > Other than that, this is by far the best built radio I > > own in terms of construction, ease of servicing and > > overall engineering. Better than my Collins, > > Halicrafters, WRL, Drake, Eldico etc. The only thing > > that comes close is my TMC gear or the T-368 - but > > these were obviously not for the amateur market. > > > > Modular construction allowed for easy replacement of a > > few parts in the modulator. I essentially replaced > > several .001 with some .02 and two out of spec > > resistors. > > > > The use of an oil filled cap in the filter was a nice > > change. Typically one has to take a small loan for > > direct replacements or cobble up a string of > > electrolytics with eq. resistors. In fact I only had > > to replace three electrolytics - the double 20 @ 450v > > and a 20 @150v. > > > > A wire brush was very useful cleaning up the milled > > edges on the knobs. > > > > I plugged all the interconnects and applied power > > through a variac. No problems at all in ramping up to > > 120v. Soon I had 150w CW and 100 phone output. > > > > I am really impressed how well the B&W 5100 is built > > and how easy it is to work on and put back on the > > air. > > > > I'll lug it upstairs and put it on the air for the > > DX-60 net tomorrow. > > > > So I ask you fellow buzzard ops, what is your favorite > > "best built ham transmitter?" > > > > 73 DE KA4JVY > > Mark > > > > > > > > __________________________________________________ > > Do you Yahoo!? > > Yahoo! Mail Plus Powerful. Affordable. Sign up now. > > http://mailplus.yahoo.com > > _______________________________________________ > > AMRadio mailing list > > [email protected] > > http://mailman.qth.net/mailman/listinfo/amradio > > > > _______________________________________________ > AMRadio mailing list > [email protected] > http://mailman.qth.net/mailman/listinfo/amradio --------------------------------------------- Introducing NetZero Long Distance 1st month Free! Sign up today at: www.netzerolongdistance.com
