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   Home   Help Search  
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 51 
 on: Today at 01:40:11 PM 
Started by EA5TV - Last post by EA5TV
Hello friends.
I am Rafael S. Lopez, EA5TV, Ham radio since 1979, but personal issues have been few inactive years in radio, being my first callsign EA5BFX, but now when I returned, I changed my callsign to the current.
My equipment consists of a transceiver Kenwood TS450S / AT and another Kenwood TS820S as well as a CobWebb antenna for 10, 12, 15, 17 and 20 m bands, and bazooka dipole for 40m band.
As the TS820S not have installed the filter for CW, the YG88C, I've been looking to buy, but I have not found one for sale, so I decided to install the YK88C filter, which has the same electrical characteristics. This is where the problem has arisen me. In reception works perfectly, being noticed much of their effectiveness, but in transmission I have to adjust the receive frequency 1 kHz up to transmit on the same frequency reception.
The question is: if the center frequency is equal in the two filters, why this happens ?.
It is also true that in some information about YK88C have seen that the center frequency is 8830.7 kHz but 8830 Khz. I have also seen different bandwidths. It may be an error in the manual and really should be 8830 Khz ?.
This is it. Any response would be welcome.
Best regards.
Rafael S. Lopez. EA5TV

PD. Characteristics of each filter

YK88C CW Filter               
Center frecqueny      8.830.7 Khz
Passband width      500 Hz (-6 dB)
Attenuatio nbandwidth   1,5 kHz (-60 dB)
Guaranted attenuation   More than 80 db

YC88C CW Filter
Center frecqueny      8.830.7 Khz
Passband width      +-250 Hz (-6 dB)
Attenuatio nbandwidth   1,5 kHz (-60 dB)
Guaranted attenuation   More than 80 db

 52 
 on: Today at 01:39:45 PM 
Started by VA2DV - Last post by N4KD
Don't. Unless you use diodes on the outputs, one supply will feed back into the other. If you use steering diodes you still will never be able to set the voltages close enough to equally divide the load between the two supplies. The one with the higher voltage will supply most of the load current.

Some supplies are designed to be paralleled and have a tracking connection between them. Unless you have one of these it is best not to parallel two regulated power supplies.


I know this sounds argumentative, but that's not my intention. I see this answer given quite regularly and I know that it's wrong. For instance, we parallel batteries all the time and nothing bad happens. We do this with regulated power supplies all the time, too. Ones that don't have the sensing connection between them are used more often than ones that do. I'd really like to see an explanation that includes a proof of why paralleling power supplies is different.

Here's my explanation... Assume that we just have two constant voltage power supplies, where V0 = V1. We connect the ground terminals together and we connect the positive terminals together. We put a load that draws current I. I like the nodal method to analyze problems like these, so that's what we'll do.
Pick a reference node from which we will measure voltages. Ground is nice for that. We only have one node left and we'll call it e. Now we write KCL (Kirchoff's current law) for the node.
(e-V0) + (e-V1) - I = 0. We can see by inspection that e=V0=V1 and that I = i0 + i1. So i0 has to be the same as i1, when the voltages are equal. If V0 ≠ V1, then i0 ≠ i1, but only by the amount the voltages differ.

If I'm doing this wrong, please let me know where I went astray. I'd like to correct my errors.

vy 73,
Dave N4KD

 53 
 on: Today at 01:37:39 PM 
Started by BRIANBURNS - Last post by AA4HA
Normally what is suggested is a dusting of "talc". This is also known as baby powder.

Graphite can end introducing some de-tuning in to the circuit.

Definitely stay away from WD-40, it has a solvent action and can loosen up cardboard forms, even if they are wax/paraffin saturated.

On the R-390A I usually clean them out with a cotton swab (Q-Tip) and then just add a slight dusting of baby powder.

There should not be any mechanical contact, or very slight mechanical contact of the tuning slug within the coil form.

 54 
 on: Today at 01:22:09 PM 
Started by N5INP - Last post by K5MF
...I also noticed the use of "purchasing" instead of "obtaining". I hope this isn't a ploy by the ARRL to generate more revenue.

Yes it probably is a "ploy," or...maybe they are just trying to cover the cost of shipping and handling.  There is nothing that says you have to buy the new certificate.  If you are happy with your old one, then stick with it.  If you get a sticker for a new accomplishment, stick it on your old certificate.  I doubt if the cost is all that much.  I asked for a new VE badge when my call sign changed.  I got the same response,  "Sorry, the first one is free.  If you want a new one it will be $5."  My initial reaction was the same as yours and then I thought, what the heck, it is going to a good cause and it probably costs that much to print it, laminate it, and mail it to me.  I piss away $5.00 on a couple of sausage burritos and a cup of coffee when I go through a McD in the mornings.  Just saying we as a whole need to loosen up a little.  In the grand scheme of things, there are, IMO, bigger things to get upset about.  Just my $.02

73,

Tom/K5MF
 

 55 
 on: Today at 01:17:29 PM 
Started by W6TGE - Last post by KJ4RWH
Somehow I read this as a window on a car!

They're known as Casement windows. I have them in my basement. They were the norm in the UK before the advent of the sash window.

 56 
 on: Today at 01:09:34 PM 
Started by KC1BMD - Last post by KA5IPF
Owners Manual for Astron RS-35M Power Supply

Plug into 120VAC
Hook radio to be powered to connections on back, be aware of polarity
Turn on Power Supply
Operate radio.


 Grin  Sorry I just had to.

 57 
 on: Today at 01:06:28 PM 
Started by WM6Q - Last post by K4JJL
I've  been using a Johnson 5100 on 900 for a couple years.  You can find them pretty reasonable on ebay.  Works with Motorola batteries and accessories, too.

 58 
 on: Today at 01:03:50 PM 
Started by WB9LUR - Last post by N4OGW
http://www.qsl.net/oh1noa/rates.htm

Minimum for SSB is 300, for CW 200 and for RTTY 120.

Email to me your highest qso rates, please inform call used, contest and if the hour was "clock hour" or "QRATE hour"(=your best 60 minutes). You can also send several rates from different contests

Here is another database of contest rates (I think more complete):

http://rate.r5ga.com/

Tor
N4OGW

 59 
 on: Today at 12:53:46 PM 
Started by K2RJK - Last post by N7RST
Just curious, what did the amp do without the tubes installed?

 60 
 on: Today at 12:49:49 PM 
Started by N5BLP - Last post by N5BLP
This TNC is advertised to work with a USB connection to the computer (and get it's power that way, too).  The TNC cannot by itself work as a digipeater (like the KPC-3+ can), so you have to get the 1270DG daughter board.  This requires configuration, and the user's guide states that it can be done while connected via USB.  Didn't work.  After 30 minutes with tech support (25 minutes of it on various holds), I'm told - no you can't configure it while connected via USB.  You have to connect via RS-232 (which requires a separate power source for the device).  Then you can switch back to USB (which requires jumper changes).  What crock.  Haven't got far enough to see if it actually works yet.  Wouldn't be surprised if it doesn't.  They haven't responded to my request to return it and get my money back.

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