开云体育

How about low-temperature solder paste? Then hit it with a hot air rework gun with the smallest tip. - Jerry, KF6VB

Donnie, testing today with an R-4, which has only one 6HS6 -- the pre-mixer. I tested 5 tubes in the socket: 6HS6, 6AH6, 6AU6, 6BA6, and the Russian 6J5P. There was no difference in the AGC set point

Sorry for the OT but I don't have a lot of options. I've searched this out and haven't found a whole lot on the subject. I have a taut band meter that was damaged during transit. The "hub" that

Thanks Steve. After swapping them into different positions on the back, the attenuation follows the filter. I did not realize that you can still buy these filters! Fortunately I have the GUF-1

I will check on that, too. These are used as mixers, so overall gain shouldn’t be as big an issue but yes, it’s important to have the bias at -1.35V before starting. Steve Wedge, W1ES Time flies

There should not be an appreciable difference amongst the various filters. Sometimes, maybe half an S unit on the 250 but most should be the same — when peaked on a single-frequency signal (like the

In addition to all that which is good, the circuits around the tubes may need to be adjusted when the tubes are changed. Ralph ku4pt

I will do so. I have an R-4B that’s coming to my bench soon and it will be a good opportunity. I don’t have any of the Russian tubes but just for the heck of it, I’ll also test with the 6AU6. I

OK, hard to say but that is quite the change in amplitude.? There are other variables as the other guys have mentioned but the 250 hz drop out specifically is definitely indicating some kind of a

When you do your test you first need to make sure the resting AGC bias voltage is properly set (Rcvr Sensitivity) then set s-meter to 1 ?Then make your test. Then after substituting the 6AH6 tube for

Jeff- I'm running a 29MHz test signal directly into the antenna jack as a reference. I don't know the amplitude of the signal but probably <1.0 microvolt. SSB filter - S8 on the meter 1.5KHz filter -

Craig, Can you quantify what "huge" means in your observation? 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com

Not being an expert, I too noticed this with C lines I owned years ago. ? Part of the issue is due to a receiver that was not properly aligned. ? That's not to say a filter hasn't "drifted" but a

Is it normal to see a big insertion loss with the Network Sciences filters? I see a huge insertion loss with the 250Hz filter, and also somewhat degraded with the 1500Hz filter. These date 76/77 so

I finally found the problem with no transmitter output. The MC1496 Balanced Modulator/Demodulator I.C. was bad. I assume whatever took out the 2N4427 buffer amplifier transistor also damaged the I.C.

This is a very long thread… have you already replaced the can cap? If not, you need to before powering up again. The blown 27 ohm resistor acted as a fuse and protected your wiring. Be sure to

UPDATE! WOW! I got a PM that directed me to check the 2 ohm resistor on the board by the relay and that was FRIED! Along with the 27 ohm resistor below it. They both were cracked in half which I

I may need to do this for the 6AH6 vs 6HS6. I have a decent signal generator now, so at least single-signal can be evaluated. Steve Wedge, W1ES Time flies like an arrow. Fruit flies like a banana.

*** Yes! That was the sort of transformer my dear departed DX40 had. In a can, sealed with tar or something. If it had been an open-frame transformer, I would have taken it apart and rewound it. -

Thanks Glen. I'm working with ngspice embedded in KiCad and have worked up a simplified circuit to simulate the DC operating point of the system. I think I finally have it working well enough to give