| Author |
Message |
    
Kattracker
| | Posted on Sunday, August 24, 2003 - 8:12 pm: | 
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I need to verify the swr calibration on the Lincoln.
The ONLY question I have is, does the letters CAL appear on your LED when calibrating to test your swr?
Per the instruction manual on page 27, regarding calibration, it says you will see a small triangle (which I do) and the letters CAL (which I dont).
Your replies will be appreciated.
Thanks,
Kattracker |
Dx431
| | Posted on Sunday, August 24, 2003 - 9:14 pm: |
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The instructions are wrong.......it will NOT read CAL on the display.....you will see the triangle while calibrating and then press the INDIC button again and the lettrs SWR will appear above the #s 7 and 9.
431 |
Alsworld
| | Posted on Sunday, August 24, 2003 - 10:44 pm: |
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Dx431 is correct. You will not see "CAL", just the triangle. You adjust the LED bars to line up with the triangle then proceed with SWR checks.
Alsworld |
Taz
| | Posted on Sunday, August 24, 2003 - 11:23 pm: |
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Yep, 431/Alsworld are correct. |
Bruce
| | Posted on Friday, September 19, 2003 - 8:22 pm: |
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Well i finaly got around to putting the 10.695 mhz channel guard in the Lincoln. After install i measured the receiver Min useable signal level as some one called it the " noise floor " at under .2UV and the filter rool off to - 10 db by increasing signal by 10 db then tunning untill the signal went back down at +/- 3KHZ from center. This seems consistant on all modes and even on narrow band fm should be ok. So in this radio the filter is a winner and i know on ssb it will when things get hot make a diffrence .... Just my opinion but a good add on. |
ss8541
| | Posted on Monday, September 22, 2003 - 10:34 pm: |
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bruce, i know you work on radios for the jail/prison. if you use the hp8920(the best monitor that we have) or the ifr service monitors, then you should be able to use the offset tracking generator option to -SEE- the actual bandwidth of the cg. we have tested the standard 10.695 filters and .455khz filters but not the cg filter. regardless of what the instructions say, the cg interacts with the noise blanker, so we do not push it.
your test may have went deeper than what you listed, i don't know, but what you listed here is not very accurate unless you were using a sinad meter with this test. .2uv is too low for a 10db am sinad and too high for a 10db ssb sinad.
narrowband fm is +/-5hz(sidebands out to 16khz), so a +/-3khz filter will cut some of this off. i do know that you are correct about ssb filtering. it will make a difference. the lincoln/2510 is bad for images due to the single conversion circuitry. a tighter filter will help eliminate this along with adjacent channel bleedover(in all modes).
i may just have to get another cg to test in some different model radios. |
Bruce
| | Posted on Tuesday, September 23, 2003 - 12:18 am: |
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ss8541
1) agree on 2950dx NB IS effected but not on lincoln at least not to any great extent mine works just fine after the filter was installed.
INFACT at the house on 28.350 it made a large diffrence sunday. I did note the path of the noise blanker and the filters insert point but in my radio the problem did not materlize.
2) I didnt use for this test SINAD meters although we have one since we rarly have a need to use one VERY few icoms ever have a receiver problems and if they do its in the factor of 10 db too low ...out of 800 we support i can remember 1 that was sick .... we measure all of them for known break squelch 99.99% will pass.... I done sinad over the years... SINAD readings are fine for a lab but my test were to show the effect of the filter and gage useble sensitity and bandpass as a end user would see it. My radio had a need for more filtering on ssb what ive found was the lincoln on ssb was a bit too wide under strong signals and the filter nicely fixes that. Im also asuming my lincoln is a average one.
3) I made my test looking ( on SSB ) for the min readable signals...as i would if on the air..... after almost 40 years my ear is good enough if i can hear it thats what counts and the readings on USB was at under .2UV my shop gen goes only down to .1UV thats FAR less than any background noise when hooked up to a real antenna. adjusting the gen up 10db and offseting to that level result +/- 3 khz was what i got..... as for fm most 10 meter fm signals work fine with these filters....Ive used then in several multimode 10 meter radios with only minor FM problems..... sure some big mouth might get clipped but im not worried.
4) on am was a bit higher but measurements were on USB maby i should have made that a bit clearer. Still AM was more than good enough a bit higher and the filter did not show any loss that i could see but the filter was installed for the SSB net/mode.
5) As for images at a 10.695 if ? i havent see any on this radio on 10 meters its as clean of birdies as it gets. Maby your think adjason channel rejection and calling that a image a image would be at 17.5 mhz or 38.695 mhz i cant see that getting through the frount end. |
ss8541
| | Posted on Wednesday, September 24, 2003 - 11:31 pm: |
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ok bruce, i thought that you may have performed your test as a 'lab' type test. if that was the case, then by what you listed, it would not be very accurate at all. but, if you can differentiate between noise levels at different tones with your ear then you have a better ear than me, and i'll take your word for it.
for 1) in your post, i have seen the cg interact with every n.b. in any radio i have every put it in, including the 2510/lincoln. i test it with a pulse generator, or the function generator option in the 8920. if you test it in ssb(the anl is inactive) and use a sinad meter(b4 & after adding the cg), you can see the that it does interact(i can hear it also).
jumping all the way to 5), 17mhz and 38mhz would be the vco injection freq to the 1st mixer(38mhz for the 2510/lincoln) with a radio with a 10.695mhz i.f. 49.390mhz would be the image for a 2510 when set to 28.000mhz. i stand corrected, about saying that they are bad for images. i should have said that they are more prone to images than a dual conversion radio. in any event, i was not confusing adjacent ch. with image. |
Bruce
| | Posted on Thursday, September 25, 2003 - 8:39 am: |
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SINAD is a nice way to measure things but on the air except for code most of us are not lissing to a single tone ....yea i know its a standard after working in engineering for many years i realy dont find " lab test " amounts to much but when i get a chance i take the time to do a 10db SINAD on the IFR on USB ( and maby am ) so we are not talking in differnt worlds....Remember after all these years its what i can see that counts... i got a feeling you and myself hooked the filter up in a diffrent place rechecking FM is not effected because when i finaly installed it is past the take off point....AM/USB IS PAST FILTER and the filter showed about +/- 3 khz at a 10 db drop. Now i have used this filter in the 2950 ( your correct the nb goes to pot although on fm it realy did not cause any problems EVEN at 3 khz )in several titans the htx-10 a grant LT ( the nb in this radio was inefective antway )On images sorry my mistake i was thinking +/- 10.7 and its -10.7 is the wanted and + 21.4 the unwanted frequency still the standard always has been that a IF should be at least 10% away ( most frount ends are not that wide except for export radios )it this case 3mhz would be a min 1st if to avoid images and i have found none on the lincoln MANY older SSB ham radios ( SWAN for one ) were single conversion with filters at the begining of the if just like the lincoln it works fine although i always liked having a 2nd filter near the detector to kill the if gain noise just before detection ....now true double convertion does help and has the added advantage of giving you a lower IF with beter gain less bandwith easer to add effective filters although a added mixer will inject noise. A well designed single conversion radio will work as good as anything if care is given to placement of IF filters and frount end bandwith.......im not impressed with triple conversion every time you mix you inject LOTS of noise .... except when we get up to the 400-1200 mhz range ....their it makes sence. |
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