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   Home   Help Search  
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 31 
 on: Today at 01:22:56 PM 
Started by KB2WVO - Last post by K8BYP
"replacing the neutralizing cap with one having a greater range I was able to neutralize the rig properly. Clearly, this is not a situation limited to 6146s."

yes, not limited to 6146. Neut capacitance is a function of Miller capacitance which is a function of (A+1) (gain plus 1) and with a different Miller capacitance, the neut cap wasnt the correct range.

Its not so easy to get small HV air variables at a wide range..

 32 
 on: Today at 01:20:30 PM 
Started by K8BYP - Last post by K8BYP
Cage match!!

This Drake looks like "we spent most of our energy on circuit design and stopped part way thru mechanism design to go to production..."

Thats typical for small projects and we must give them a break, this was ground-breaking work to develop the first ever Amateur Transceiver, which, BTW, is not a Boat Anchor
at only 12 lbs. (PS not included).

The VFO mechanism is an 'immature' design (not developed fully).

Am working on fixes...

 33 
 on: Today at 01:19:31 PM 
Started by N3QE - Last post by KI4ENS

Review the on-line form from the UTC website. Fill it out, wait 30 days you'll either be approved or not almost everyone has been approved.
https://utc.org/plc-database-amateur-notification-process/

Here is the FCC official order.
http://www.eham.net/articles/40106
Bill, AA2UK

Quick question,  how does the UTC notify the amateur radio operator?  I filled out the form and have not heard anything.  Not even an acknowledgement of me filling the form out.

thanks
Max
KI4ENS

 34 
 on: Today at 01:14:57 PM 
Started by K8BYP - Last post by K8BYP
Good read:

https://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm

And...

http://en.academic.ru/dic.nsf/enwiki/19981#Failure_modes

and

http://www.antiqueradios.com/chrs/journal/rejuvenation.html

www.cathode.com/pdf/TB-134.pdf

https://descanso.jpl.nasa.gov/.../Goebel_06_Chap6_cathodes.pdf


 35 
 on: Today at 01:07:47 PM 
Started by VE3VEE - Last post by W6OU
VK9CI (Cocos Keeling) via LOTW.

 36 
 on: Today at 12:54:32 PM 
Started by K9RE - Last post by KA4DPO
  Cry

This whine is not really customer service   Huh , and borders on their business practices and many thanks to staff who have tried to help me but are required to follow the company business rules.

New products always have their growing pains.  But ICOM et al have really bungled the roll out of this newest in the true SDR Series.



So how is any of this Icom's fault?  DXE are the ones who took early deposits for first dibs, Icom just ships the radio to vendors, they don't tell them how or to whom they sell them.

Your beef is with DXE and them alone.

 37 
 on: Today at 12:54:14 PM 
Started by VE3VEE - Last post by N5MOA
HL5IVL, 160m cw from 2013, LOTW

 38 
 on: Today at 12:49:09 PM 
Started by KE6US - Last post by WA2CWA
Not entirely a new or novel concept in using incandescent lamps as a low power “TR Switch” or as a receiver front end protection device way back in the good of days of the 50’s.

As pointed out, cold resistance of incandescent lamps is very low. As the lamp filament lights, its resistance increases.
So, back in the good old days, you connect your antenna to your transmitter output. At the transmitter output, you connect one end of a typical 7.5 watt lamp to the transmitter output. I used those old colored Xmas tree lamps. The other end of the lamp would go to the antenna connection of the receiver.

Most receivers of the day used front-end antenna coils to mate between the antenna input connection and the front end of the RF Amp. tube. The antenna coils had a secondary winding which faced the tube input and a primary winding which faced the antenna input connection (“A” and “G”) and generally consisted of only a few turns and  heavier-type wire. One end of the primary antenna coil would go to the antenna input (“A” screw) generally via the bandswitch. The other end of the primary antenna coil would be grounded.
Since one end of the incandescent lamp was grounded through the primary winding of the antenna coil, as RF was applied, lamp would light, and series resistance would increase. When not transmitting, the receiver antenna connection (“A”) was connected directly to the antenna/transmitter output connection via the incandescent lamp. There typically would be some interaction with the plate/load settings of the transmitter with receiver reception.

Obviously, transmitter power output range would be a major concern in size of the incandescent lamp and how much RF power could be handled by the primary of the antenna coil in a typical boatanchor receiver of the time. I used 7.5 watt lamps as TR switches in several 6 meter and 2 meter 2E26 rigs that typically put out about 7 to 9 watts. I believe if you check in some of the 50’s ARRL Hints and Kinks and/or their VHF manual, you’ll find some similar info in using these lamps as low power TR switches.

Pete, wa2cwa

 39 
 on: Today at 12:42:15 PM 
Started by VK3BL - Last post by AF6LJ
This is an interesting thread.
Measuring IMD isn't as straight forward as most would like to think. SDRs may not be the ideal choice for those measurements and one must be careful using an analogue spectrum analyzer making such measurements as they can be overloaded well before first mixer overload occurs.
I've done plenty of measurements with analogue analyzers, enough to know that how the test environment is set up is way too important to take casually. I would assume that the same holds true for the modern digital analyzers. As far as SDRs goes...
To put it bluntly; making any claims based on what a computer A to D, or a 10 or 12 bot run of the mill ADC presents is scary to say the least. The A-D subsystems built into modern analyzers are far more trustworthy.

 40 
 on: Today at 12:40:57 PM 
Started by K6REA - Last post by K6REA
boy...talking text to your phone to post a message on a board, isn't always accurate..
it should read...

I'm going to mount a 5-element 2 Meter yagi which will be horizontal and an arrow antenna model  146/437-10 , on the same boom.
How far apart horizontally should I space these two. I'm putting them on the same boom because I only have one Rotator system.
The 2 meter yagi will be used for sideband horizontally and the arrow antenna for satellites.

Thanks,
Kevin Rea
Lancaster, Ca
K6REA

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