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 31 
 on: Yesterday at 09:25:00 PM 
Started by KG7LWZ - Last post by K0ZN

 Normally, the system configuration is:

 Tranceiver --> Amplifier --> SWR/Power Meter --> TUNER --> Antenna

 I guess you could do the set up the way you indicated, but all you would know is what the "raw" SWR is on the line between the Tuner and the antenna; that meter
would be useless for tuning the tuner in that configuration and you could also get erroneous power readings due to the effect of SWR. How do you adjust the tuner for lowest SWR match to the radio? You must have a tuner with an SWR meter built in or be using the SWR meter in your Tranceiver to tune the Tuner to a match that yields a low SWR for the rig.

73,  K0ZN

 32 
 on: Yesterday at 09:16:04 PM 
Started by KG7LWZ - Last post by KH2G
Since you don't need the tuner on your normal bands, If your radio has a separate ant jack for one of the HF bands, Hook that jack to the tuner for your 2 bands and program the radio to switch to that jack when you go on those freqs. (That's what I'm doing with my T2K and it works fine and I don't have to remember whats where).  Grin
Regards,
Dick KH2G

 33 
 on: Yesterday at 09:15:39 PM 
Started by BOOTYMONSTER - Last post by HFHAM2
The Icom IC-718 is an excellent beginners (and experienced casual ham's) rig.

Very straight-forward in use, very little buried in menus, bulletproof, just plain works and works.

Someone mentioned a TXCO but no-one needs a TXCO for home use; modern rigs like the IC-718 are plenty stable enough without spending all that on what is essentially a farkle.

Another mentioned the Alinco SR8T, I tried one as I was tempted by the "free filters". Well, the (fixed-width audio) filters are pathetic, especially for CW and you can't buy optional filters for that rig even if you wanted to (which you will). I took mine back to the store for a refund the next day.

You can get by quite well with the IC-718 using the IF-Shift and/or CW-R mode to side-step QRM; most also have the audio DSP noise reduction and auto-notch module installed too. Option filters are available (yes, they're expensive but very effective) or you can use an inexpensive outboard audio filter or SCAF type filter (NEScaf, SCAF-1, etc.)

The IC-7200 and FT-450D are supposedly "better" (I don't know), but they're also more complicated and more expensive and less likely to be available on the used market.

You can't go wrong with a new or used IC-718 in my opinion. The Alinco SR8T is fine for SSB, but it's not a CW rig and can't be, due to the filtering (or lack thereof).

 34 
 on: Yesterday at 09:05:10 PM 
Started by K9BAY - Last post by K9BAY
I guess that means I am out of luck until I get my radio and tuner...  Sad

Thanks!

 35 
 on: Yesterday at 08:57:17 PM 
Started by KG7LWZ - Last post by N7WR
You will fry the tuner.  It is rated for 300 watts going through it in line or bypassed...plus, even if it could handle it bypassed (it can't) it would be too easy to forget it was in line

 36 
 on: Yesterday at 08:42:45 PM 
Started by N3DT - Last post by N3DT
I'm sorry, but I must be dense.  I just don't understand how the NC circuit 'opens up the circuit' (which one?).  When I look inside Dow Key, there's the contacts on the NC and NO connectors and the long central contact from the COM. Does the 'G' relay do something to the COM circuit that I'm missing?  I have some relays that short the non used ports to ground (shorting relays), but I take it this is different.

I still would like to know how to tell the diff between the 'G' model and the non- 'G' model. I've sent a email to Dow Key about one I have that's black anodized with no markings other than 24VDC.

Thanks,
Dave

 37 
 on: Yesterday at 08:38:25 PM 
Started by K9BAY - Last post by WB6BYU
You can tune a manual tuner using an antenna analyzer.  But an automatic one
requires RF to operate - typically a few watts minimum, and an analyzer won't generate
enough power to activate it.

 38 
 on: Yesterday at 08:27:53 PM 
Started by KG7LWZ - Last post by KG7LWZ
Not sure if this is a simple question or not. So here goes.

Normal configuration order would be: Transceiver - Amplifier - Antenna Tuner - SWR/Power Meter - Antenna

Assume that the Amplifier is a 1kw amp. Assume for a second that the antenna tuner can only handle 300 watts. Assume that the antenna is a FAN-DIPOLE with resonant bands of 80, 40, and 20 meters.

I know if I have the power off to the amplifier, the transceiver can operate on any of the resonant bands of the antenna with the antenna tuner in Bypass mode.... or tuned to any other band/freq using the tuner. The question is: When the antenna tuner says it can handle a maximum of 300 watts, does that mean just through the tuner, OR ALSO when in the "Bypass" mode? In other words, when using the actual tuner to tune non-resonant frequencies, and the amplifier is powered off; all should be good. But if I power up the amplifier and have the antenna tuner in bypass mode, should I be able to transmit 1kw from the amplifier through the bypassed tuner to the antenna; without hurting the tuner.

Most of the time, I'm on the 80, 40, and 20 meter bands. My dipoles are resonant so I don't need a tuner. I only use the tuner for 17 & 10 meters, but that's rare, so I don't want to buy a NEW antenna for the rare times I use those bands. But I also don't want to have to manually cable and un-cable the tuner into my rig on those times I want the 10 or 17 meter bands. Any thoughts??? Thanks. Mike....

 39 
 on: Yesterday at 08:27:24 PM 
Started by W2AEW - Last post by N3DT
Kerry,

I'm glad you posted that, you're way past my pathetic measurements.  I'm lucky to get to 70cm.

That said, I'd like to know what happens when you attach a piece of 50 ohm coax to the RLB.  Lets say 100' of FSJ4-50B with open end. If I have a ref load of 50 ohms I still see up and down voltages on the diode end with freq changes, not unlike when I have no ref (infinity) but much less variation.  I measure the RL compared to a 1dB step attenuator and I get somewhere between 1-2 dB, which I read as .5 to 1 dB one way loss in the cable.  But it sort of depends on the freq and it goes up and down quite a bit depending if you're near the half wave point. I would hope the RL goes up with freq.  I'd like an explanation of that.  Or maybe it needs no explanation, the measurements work anyhow?

I'm also interested in how you can measure complex Z with the RLB if I read your post right.

Dave

 40 
 on: Yesterday at 08:19:56 PM 
Started by AD5QA - Last post by AD5QA
Thanks,

I just cracked it open and looking into it a little more. I don't think it is the module and may seem to be the driver or something. When I key down the radio does not even attempt to transmit on UHF. The VHF works and sounds fine putting out 50 watts. The fan in the rear was defaulted as off and I reversed that as it was warm just receiving. I grabbed the datasheet for the Q08 MRF599 and will probe around tomorrow to see if I get any readings. Just downloaded the service manual and found that the MRF599 is not expensive. If that is a common failure then that will be my starting point. Will measure and find out if that is bad or not. If not I will have fun tracing it down lol, will look closer for any heat damage. I hope I remember to grab my IR thermometer from work tomorrow.

http://pdf1.alldatasheet.com/datasheet-pdf/view/76514/MICROSEMI/MRF559.html

Tom AD5QA

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