Considering the preceding email; Would it make sense to directly ground SB-220 grids and fuse the filament/bias transformer such that a ground fault would interrupt filament, bias, and HV? I would pr
The Harvey Wells Bandmaster used an 807 (or a 1625 - memory fails me) on 144 MHz. This was back in the 50's. I beleive that the rig used the 1625 as a tripler. Not germain to the subject, but it does
My Harvey Wells Bandmaster uses an 807 final and operates on 1.8 to 148 mhz. (actually it is mcs., since it was built before the great conversion). The actual output of mine on 50 mcs. is 4 watts. On
Some kind of a grid fuse is useful to preclude grid/fil shorts. . It can go anwhere in the path of grid current. Only grid current need be interrupted. I would put a MOV across the fuse. end - Rich.
That's one solution Art, if it accompanied by HV current limiting in the form of a HV rated current limiting resistor in the HV lead. Remember the HV fault inside a tube is normally from anode to gr
Tnx. At this time I have a 25 Ohm 20W resistor between the output of the rectifier/meter board and the input to the HV choke. It is one of the brown tubular units (it is fairly long. . .). .'goes aro
There was an early VHF transceiver for the RAF (late 1940) that used a specially selected 807 (called an 8018) at 120MHz. It was sort of Class C, but they modulated the driver - don't know why. Still
How much DC input, though? I bet a pair of 7193s or an RK34 would be more efficient. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative r
73 magazine has no technical editor. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests:
I really can't remember if it had back then - we are talking of over 30 years ago. I found it quite a good magazine in those days, despite Wayne's ramblings. I gave up when it went mad on FM and repe
Th Harvey Wells Bandmaster, using the 807 ran about 30 watts input and had, I am guessing, about 1/2 watt output on 2 meters. No grid drive was indicated, all in accordance with the manual. Quite a m
As Colin says, a model of efficiency! Somehow, I don't get convinced that these big old tubes with long internal leads are really the best choices for use at the higher frequencies. 73 Peter G3RZP --
You guys have to remember that this was not a vhf transmitter. It covered all the way from 80 meters to 2 meters. Quite a challenge, especially at that time. 73, Harry, W3IIT Microwave Update/Hamaram
Hi Harry: If you will note in the Harvey-Wells manual, it actually covered from 160 meters through 2 meters, even though the bandswitch only went to 80 meters. The manual tells you how to operate on
My favorite 73 magazine article was one with three or four TV power transformers in series, running a kilowatt linear. No chassis safety ground either. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW
Indeed. With a prayer-cloth dust cover and a plastic matt to stand on, why not? // For sheer laughs, the cold fusion conspiracy is hard to beat. cheers - Rich..., 805.386.3734, www.vcnet.com/measure
Since the performance was so poor from an efficiency point of view, I have to query the rationale behind doing it. If it's just a case of put 'more bands on it so people will think it's a better barg
For HF, it has some interesting problems in getting the correct phase match over the whole spectrum. Inherently, that also requires accurate matching in the time delays, too - effectively putting a v