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and when the band is closed, then a piece of wet string will do wonders.

The big issue will be to have adequate control measures in place to stop it taking off and also to shut it down when a problem occurs. Best bet is to try and find another op using that tube and gleem some info from them on how they control it.

I don't think your house wiring will handle that load. Best leave well alone and dream on.

Hope you got a beefy psu to power that tube ? I would rather get a QY5-500...HI or a pair of them. GU39B-1 Type tetrode Cathode type tugsten,carbidized,direct heating Application field power amplification in SW transmitters Brief application amplification Envelope glass to metall Cooling method...

Hi, Ok I already have a glitch resistor on the HV line. I was wondering if moving the dc block caps would affect the higher bands or not. I will try a higher dump resistor of 1K and see what results I get. Thanks again for the info.

Here is a question for the experts, What difference if any does the positioning of the dc block anode caps have on the tubes anode impedance. Traditionally, its mounted close to the tube's anode, but what happens to the line if its mounted closer to the plate cap. Is there a difference on...

I moved the plate cap earth strap as close to the tube base as I could ( actually right onto it ) and this has now given me 200w out on 15 and 100w out on 10m. I am looking for some silver plate flat strap with which to rewind the 10m coil. Hopefully that will bring it in even more. No surplus...

Update: I am making a 10m tuned input and just waiting for some ceramic trimmer caps to arrive from ebay, which I will use in the final circuit. I will use some sm caps I have which are low voltage 50v and see what the MFJ says. Another question on the grid input...Its got a 300R dumping...

Would,nt think so. These devices now days are very robust. If the smoke was not let out , then its all okay.

Hi,what I meant to say was that I used the 80m bandswitch position just to test and see if I could get 6m to dip, which it did. Ok, well I put the chassis back into its casing and fired it up. Still very little output on 15 or 10m. However The lower bands have seen some improvement. The drive...

80M is also ok as is 50Mhz, which is surprising. Is this the norm for a HF amp to work on 50Mhz when not really designed for that band? I have a length of 10mm silver plated copper strap from the tube anode to the two dc blocking caps which is about 3 1/2 inches long and the 50Mhz tap point is...

I have now re-assembled the tank components again and rewound the 10m coil with 3.5mm copper wire spaced wire thicjness and 5turns. 15m came in straight away as did the 10m band. Now I just have to add the 80m coil and see how far it will shift the higher bands, if any. Thanks for your help...

Thanks for the reply. I removed the plate cap to cleaned it out and found that the two brackets which hold it fast were heat fatigued and snapped off in my hands. So just waiting for some to arrive in the post via ebay. There is plenty of drive as seen on the grid current meter on 10m and good...

One thing I am checking is the gap between a dividing alu wall and the plate capacitor. However, the stators are already on the dividing wall side, but thinking the rotors are also about 10mm from the dividing wall when on minimum tune position. I have now removed the capacitor and will place...

No, Its a basic electret capsule, obtainable for a few pennies or cents or whatever your currency is. Ebay number is 360765304721 You will need a 5v supply line to your mic if not a ft897 rig. See this link for instructions http://in3eci.it/bbb/file_content/fl219.pdf Once the mod is made, go...

I have a FT897D whose transmit audio leaves a lot to be desired. I removed the original mic insert, threw it away and replaced it with an eletret capsule ( 5mm dia one ) and have not looked back. Every report is now a beautiful strong audio and excellent audio. I really don't see the need to...

Verticals are ok if homebrew, but the commercials one's cost an arm and a leg. I am happy with this loop and its low noise properties. Ok, so I need an ATU but losses are minimal with a balanced ATU and ladderline feed anyway. I must try a dedicated loop cut for 6m and see how that performs.

Thanks, I was also impressed at how well it works close to the ground. One would expect it to be a cloud warmer, but its not. I dont have a big garden, hence the small sixe, but its definitely a good antenna. I would never go back to a dipole or endfed wire again. Next step it to place another...

I put up this loop 8 x 6m vertical standing, whose bottom is 1.3m off the ground on a wooden garden fence and its performance is very good. What a lot of people dont realize is that the radiation patterns are also very good and improve on the higher hf bands. I feed mine with 450R ladder line on...

Hi all, I am running a grid driven QY5-500 TUBE with zero bias and the screen voltage is derived from the rf drive into G1 for now. The age old problem of low output on 15 and 10m has reared its head. The input into G1 is via a 50R matching toroid transformer and I have 3kv on the anode...