On 1/28/09 10:45 PM, Joe Hutchens wrote:
> I've had the antenna selection switch on the back get dirty. Cleaning it
> solved my problem...back when I had a 509.
>
Thanks for the idea. Bypassed the switch, no big deal since I'm not
using a separate receive antenna, no change in sensitivity...
OK, who's next ;-)
73s, AJ4LL
> --
> Joe Hutchens ( AJ8MH )
> http://webpages.charter.net/aj8mh-radio/
>
> ---- Roscoe Primrose<roscoe@aiko.com> wrote:
>
>> My Argonaut 509 seems to have a serious receiver sensitivity problem.
>> The other night when 80M was fairly noisy, I was getting noise at S6-S8
>> on an FT817, hooked the same antenna to the 509, an even with the RF
>> gain all the way up, the S-meter baorly moved, if at all. RF noise is
>> generally not enough to move the S-meter, and I've made several easily
>> understandable QSOs with no motion of the S-meter. The S-meter is
>> working, with very strong signals it does occasionally get up to S-9. I
>> originally thought the problem was the first stage dual-gate MOSFET, but
>> I'm pretty sure that's not the problem at this point. When
>> troubleshooting the first stage MOSFET, when I hooked a DMM lead to gate
>> 1 I get a stronger signal (not just noise, but signal as well) from the
>> test lead than I do from the antenna connected to the unit. On the RF
>> front-end board, the antenna signal goes through an input cap, a
>> transformer/cap combination that's a 9MHz trap (VFO), through a tuned
>> transformer which is part of the pre-selector, through a coupling cap,
>> and to gate1 on the MOSFET. Connecting the DMM lead directly to gate1
>> causes an increase in signal& noise, connecting it anywhere before the
>> coupling cap results in no change in signal level. I changed the
>> coupling cap, but there was no change in performance.
>>
>> Anyone familiar enough with the front-end on these rigs to have an idea
>> as to what I can check next?
>>
>> Thanks, AJ4LL
>>
>> --
>> "The tree of liberty must be refreshed from time to time with the blood of
>> patriots and tyrants. It is it's natural manure."
>> Thomas Jefferson, 1787.
>>
>> _______________________________________________
>> TenTec mailing list
>> TenTec@contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>>
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
--
"The tree of liberty must be refreshed from time to time with the blood of
patriots and tyrants. It is it's natural manure."
Thomas Jefferson, 1787.
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|