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 on: Yesterday at 08:34:04 PM 
Started by W1KSZ - Last post by N1BCG
If you enjoy ops on AM, then it could make a difference and the wiring will determine the phase of your typically asymmetrical voice energy.

Wire the microphone either way and observe your modulation on a scope or mod monitor. If you tend to hit the baseline (carrier cutoff at -100%) more than +100% on average then reverse the leads. If your positive energy is greater than +100% when the negative peaks are just reaching -100% then your microphone is optimized for that transmitter.

Wiring the microphone in this way will dramatically reduce distortion depending on your transmitter if you are using it on AM. Think of this as an opportunity to wire your microphone correctly for your transmitter.

 on: Yesterday at 06:27:30 PM 
Started by AJ1G - Last post by kd1nw
I'm using an arris / surfboard sb6182 and it seems to be pretty good. the surfboard is a cable modem only, no phone line and no battery. I just went downstairs with a portable shortwave on 3.885 and i had to get within 6 inches to hear anything from it. i got the radio a good 2 feet away and then brought the power cord from the wall wart toward it, i had to basically touch the wire to the radio to hear the rf from the power cord. placing radio near the wall wart produced the same racket when i was about 3 to 4 inches away. at least I don't have to unplug it like my previous unit which was by zyxel.. that thing was attrocious S9 to +10db broadband hash from at least BCB to 30MHz. I could walk around my yard 200 feet away from the unit and I could still hear it. the zyxel unit had a battery so I could unplug it and eliminate the noise when i wanted to operate, verifying what Clark and Bob said.. the switching power supply.

I guess I'd be careful of my "endorsement" though. I've had the sb6182 for around 5 years i think and I would suspect that arris uses different parts and suppliers for various runs of the sb6182.. pcb board revisions, different supplier of wall wart etc.. they could be noisy now. I would say make sure you know the return policy before buying in case it's unbearable. Good luck and let us know what you find

P.S. Sorry Chris, I was going to say you could come over and evaluate it yourself seeing as you are close by but I just saw you need phone support which pretty rules out my unit working out for you. Sorry I just caught that...

73 Kevin

 on: Yesterday at 06:23:22 PM 
Started by W1KSZ - Last post by KD6VXI
It doesn't matter.  A xtal microphone is an AC source.


 on: Yesterday at 05:05:27 PM 
Started by AJ1G - Last post by W1RKW
I echo Clark's assessment. I don't have a cable modem but a DSL modem and I'm on my 3rd one in 12 years which I bought online to get away from the 2 provided by the phone company.  My SNET one died, not sure why. The Frontier modem was a POS. And the current one is an Actiontec which works wonderfully. That being said, they all had one thing in common and that was a SMPS. The power supplies were polluters. My solution to reducing significantly or eliminating RFI was to shield the SMPS wall wart in a metal electrical box which was grounded to the electrical ground.  For the Actiontec I got away from the shielding and simply went with a linear wall wart. The SMPSs will crap out over time too. So simplified my life and went linear. Again, RFI gone and hope this PS out lives the SMPSs, so far so good.. And a side note, all modems were in close proximity to my radio gear.

 on: Yesterday at 04:29:56 PM 
Started by WA4WAX - Last post by WA4WAX
If anyone wants pictures, I will post some.

Well, this beast came to me in an original box, which I saved.  Open it up, and it is 1951 all over again!

It lit up nicely, but would not zero on ohms, AC, or DC.  It had been sitting in a closet for some time.

I looked at the schematic, and decided to try something.  With the meter out of its case, and the mode switch in AC,  I rotated one of the 2 pots on the top left. It has to do with 6AL5 contact potential, but also seems to have some sort of balancing effect.  Suddenly, the meter needle came off of left pegging! I put the zero pot in the mid-range position, and tweaked the internal pot until the needle came close to zero.  I tweaked some more until I could zero on all ranges, from 3 VAC to 1200 VAC.

To my surprise an delight, the beast was now zeroing on DC+, DC-, ohms, and caps!  Wowser!

I found two more pots, both on the bottom of the chassis, and both tough to reach.  These I identified as the DC and AC calibration pots. 

Using 3 9 volt batteries in series (Measured with Fluke 87 Mark III) as a calibration source, I set the beast right on the money on the 30 volt scale.  I then proceeded to test it on all DC scales from 3 volts to 1200 volts. My IP-2717a entered the fracas.  In all cases, the 209A was spot on......1% or less compared to the Fluke DMM.

The story of the ohm meter was similar. I had a glom of Shallcross Acra-ohm pieces, and put them to good use.

On AC, I have yet to set the calibration.  Nonetheless, it is already within 5 or 10%.  I did check the peak to peak function, and it works nicely.  I have yet to test it on a capacitor.

All of this with the original bottles, electrolytics, postage stamp micas, paper caps, etc.  Some times you just get lucky. Yes, many of these "danger" components will soon go, along with those pesky phone tip jacks.


 on: Yesterday at 02:38:49 PM 
Started by W1KSZ - Last post by W1KSZ
I decided to update my D-104, big mistake, my old element worked just fine.

So, I decided to put the old element back in.

Stupid me, I didn't write down which wire (Red or White) goes to (+) and (-).

Can anyone help this dufus ?

Tnx, Dick, W1KSZ

 on: Yesterday at 02:08:28 PM 
Started by WO4K - Last post by Pete, WA2CWA
Attached is a photo of my Viking II CD version.

Exact same artwork that was on the one I had Tom.  Seems the "All Viking II-CDC's had only the "CD" logo on the upper left of the front panel." statement is in error!

All the ones I've seen and owned over the years had Johnson Viking II-CDC  printed over the plate tank tuning dial and the CD decal on the upper left. This is also what the brochure showed. In the picture below, you can see where the CD decal was removed on this Viking II-CDC.
Bottom line, "who cares"; Johnson only made three versions of the Viking II. The consumer version in kit form, the consumer version in factory wired form, and a Civil Defense version in only factory wired form (which obviously had front panel logo printed with either "CD" or "CDC").

 on: Yesterday at 01:57:13 PM 
Started by ashart - Last post by ashart
Alpha 77D grounded-grid linear amp. Selling to help XYL of SK ham. Picture shows 1500 watts carrier output as thatís the limit of my (not-included) B&W dummy loadís wattmeter. Grid current only 130 ma. Drive only 40 watts. Gain 15.7 db. ETO
specifies the 77D at 3000 watts PEP Continuous Duty with 100 watts drive.
You or your agent welcome to see it operate, in Farmington Hills, MI. Will sell for
$3450. or $3850. with the spare Eimac 8877. Includes manual and AC power cable.
Payment in cash or to Paypal. After payment, you can pickup in Farmington Hills, MI, or I will drive up to 100 miles to meet or deliver, or will ship to your CONUS address after secondary payment of Fedex direct charges to professionally pack and ship. If you find the amplifier to be materially different from how Iíve described it and pictured it here, just return it within 14 days of receipt, in unchanged condition, freight prepaid, and Iíll return your full purchase price. BUT, if the amplifier has components burned or charred, or arced over, or otherwise misused, or the 8877 has been destroyed by excessive grid currents of improper tuning, it is NOT returnable. By purchasing this potentially-lethal amplifier, you are representing that you are experienced in all phases of ownership and operation of high-power amplifiers, and that you will always follow all appropriate safety procedures. Was limited to 3 pictures here - have a couple more if you wish.  For a reference, see ebay seller ashart. Contact: al hart via al@w8vr.org or via ash@attorneyhart.com or at (248) 626 4706.

 on: Yesterday at 01:12:49 PM 
Started by AJ1G - Last post by N1BCG
You may find, as I did, that most of the HF RFI generated by cable modems and routers comes from their power supplies. I've tried several and this was the case 100% of the time.

I solved this by using an analog 12V power supply (1974 Archer CB Radio Power Supply) which easily had enough current capacity to power both the cable modem and router. The latter has numerous long CAT5 tentacles reaching out throughout the house, thus the importance of RFI reduction/elimination at the source.

Another approach is to use very high permeability toroids and wrap both the power cords and 12V output leads through them. For "wall-warts", you'd need to plug them into an extension cord to accomplish this.

 on: Yesterday at 12:53:24 PM 
Started by WO4K - Last post by WD8BIL
Attached is a photo of my Viking II CD version.

Exact same artwork that was on the one I had Tom.  Seems the "All Viking II-CDC's had only the "CD" logo on the upper left of the front panel." statement is in error!

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