I just bought a Heathkit SB-1000. After replacing a couple burned-up ceramic caps and removing RTV someone coated the plate choke with, I was satisfied the thing was working. I had it hooked up to a spare rig and a cantenna, and was getting a full KW out. I then moved it over to my main rig and a real antenna. I goofed up and got the RF in and out reversed, so my rig was transmitting into the output. Now I'm getting no power out at all. The high voltage is there, but I'm getting no plate current or grid current on the meters. What did I likely damage? No smoke, BTW.

ND9B 

What would cause C409 and C411 (very small .01s in the voltage doubler) to burn up? I can't find any thing wrong. I replaced them with large 1kV ceramics, and the new caps are holding up. Can anyone explain why the bottom of the voltage doubler goes through a diode and choke instead of directly to ground?

ND9B

I just bought a used Heathkit SB-1000 linear amplifier. I'm cleaning it up a bit before putting it in service. While I have the cover off, I'm wondering if it would be a good idea to clean the wafer switches with DeoxIT. Would this cause arcing or anything bad?

ND9B

A theory just occured to me on this. The spark plug wires are about a 1/4 wave length long at 147 MHz. Maybe the ferrites just detuned the sparkplug wires off resonance. Does this sound plausible?

ND9B

I've had severe ignition noise on the 2M band in my little British roadster. Just as a lark, I tried putting some small TDK ZCAT1518--0730 clip-on-ferrites on the spark plug wires. I didn't expect it to help, but it completely knocked out the noise! The spec sheet on these clip-ons only rates the impedance as 100 ohm in the 2M band. This car has resistor sparkplugs and resistor sparkplug wires that add up to many, many K ohms. How on earth could the ferrite's puny impedance make such a difference?

ND9B

Well I found a meter that really fits the bill, the Ameritron AWM-30. This thing really detects peaks on both forward and refected power. It manages to find the peaks in normal speech and holds on like a pit bull. There's no need to "eat you microphone" calling "heeeeeeeeelloooooooooo"! This is a good "while you talk" meter. I get readings on SSB just as easily as CW. The case is rather plain, but a perfect match to my Ameritron amplifier.

ND9B

I'm looking for a cross needle power meter that has GOOD PEP reading on BOTH forward and reflected power. My Ameritron AL-80B amplifier has such a meter. I can see at a glance if the power and SWR are good WHILE I'm talking. Unfortunately, I can't use the Ameritron meter when operating barefoot.

Oh, this meter would be for HF for both 100W and 1000W operation.

ND9B

I have a Yaesu FT-857d installed in my little British roadster (MGB). I have a 102" whip clamped to the back fender for HF (with an antenna tuner), and a magnet mount 2M FM ant on the trunk. There was a lot of ignition noise on HF, but after installing ground straps and resistor spark plugs, the HF bands are very quiet.  But all the work I did getting the ignition noise out of the HF band did not help 2M one bit.  The ignition noise is so bad on 2M, that I can't copy the local repeaters only a few miles out of town. (Yet, I can tell the voices are there 40 miles away.) With the engine off, reception is just fine.

Any ideas on how to fix this?

ND9B

Hi WB2WIK, there must have been a few ECOs on this model since you left. The actual sweeps are done with MC1648 oscillator chips one for each IF of 1.2 MHz, 10.7 MHz and 89 MHz. A single additional MC1648 is used for 262 KHz and 455 KHz. These are sweep using a 60 Hz ramp signal into varactors. In sweep mode the LMO is used as an adjustable marker.

My 103B has a board that generates an "intensity" marker. I actually have a second unit that is the same way. Neither one makes a marker on 262 KHz, 455 KHz and 1.2 MHz. I'm trying to find out if this is normal.

The 103B manual, I downloaded from the internet, does not show an "intensity" marker. I suspect it is for a variant model that uses a "blip" type marker. The manual refers to a "blip", but doesn't elaborate. It also doesn't indicate any IFs the marker doesn't work on.

Booby Dipole ND9B

Actually, the old mechanically tuned Delco car radios used an IF of 262 KHz on the AM band. (BTW, I retired from Delco.) Some of the newer ETR models use up conversion with an IF of 10.7 MHz FOR AM, believe it or not!

Bobby Dipole ND9B

I hope this is the proper forum for this topic. Anyone out there have this RF generator? I'm trying to use the sweep capability of this generator for aligning IF strips. My 103B has an "intensity marker" output on the back that I have connected to the "Z axis" input of my scope. This works, but only on the higher IF frequencies - 10.7 and 98 MHz. 262 and 455 KHz sweeps have no marker. I have a manual for the 103B, but it does not show an "intensity marker" output. There is also an extra circuit board in my 103B that does not show up in the manual. Evidently this extra board makes the "intensity marker" since it connects to the "intensity marker" BNC connector.

Should I be getting a marker on the lower sweep frequencies?

Bobby Dipole ND9B

Got the YIZHAN a few days ago. Works as advertised, no complaints. It's a little on the large side, but very light. The digital current and voltage readouts are nice. The current limiting control is a nice feature, you can use it as a constant current source if need be. I had to pay extra for the 110V model. (In actuality, I don't think they manufacture a 110V model. I think the supplier takes a 220V unit and modifies it for 110V. There is no separate model number for the 110V unit!) The unit came with a funky 220V plug on the line cord. Fortunately you can use the line cord from a PC.

I'm using this strictly as a bench supply, not for my rig. But, I did a little tuning with the supply turned on and under load. I didn't notice any spurs. (It has more than enough capacity to run a transceiver, but I would consider it dangerous to use a power supply that could go to 30V if the control were accidentally "bumped".)

Bobby Dipole, ND9B

My 2 meter rig killed my MP3 player.    I was listening to the player with earbuds, keyed the mic and that's all she wrote. And , no, a reset did not fix it. It was a hardware failure. So maybe legal limit on 2M?

Bobby Dipole ND9B

I've been looking for a low voltage adjustable bench power supply. The YIZHAN 3030D looks interesting, 0-30V, 30A, adjustable voltage and current. Any opinions on this model? It looks to be available only on eBay from China. (It's a switcher, but I'm not going to use it on the air.)

Bobby Dipole ND9B

First off, I'm a newbie on eHam. Is this the right forum for antennas?

I would like to set up an external antenna for an antique AM radio (1936 Zenith Console). I've already tried the following:

1 - A random length wire. Picked up lots of signal, unfortunately it picked up too much household noise such as the stove, DVD player (even when it's off), the CFL bulb in the living room, basically anything that pulses or has a micro computer within 10 feet of the wire.

2 -  An outdoor dipole with 20 foot legs using RG8X for lead-in. This still picks up some noise and is weak on the low end of the band. I figure such a short dipole is a horrible match to the coax, especially at the low end of the AM band.

I'm thinking that a high impedance buffer at the antenna might be just the ticket. I have experience with JFETs, and the power could be supplied though the coax. Assuming a high impedance buffer is the way to go, should I try a whip antenna? Would the whip antenna need a counterpoise or ground plane? I still have the short dipole up. Could I put the buffer on the leg that goes to the center conductor of the coax, and leave the other leg hooked to the shield? Or would the buffer need to be differential to make the dipole balanced? At any rate, it's important that the coax doesn't pick up any noise on it's route through the house.

Bob D. ND9B