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Gordon Gibby
开云体育?I'm close to trying John?radiomanjwt's quick-and-dirty mods to allow the bitx40 to? have some output power on 80 meters....
I just want to confirm that while the 470pf spans the beginning to end of the BandPassFilter....
on the (output) Low Pass filter it only connects across L7 and not across L6 ?? or both??? in one of his posts he said it went across L6 and in another he said across L7? so I'm a bit confused.....
Any clarification?? ?
I have a short article on the very basics of bringing up a bitx40 with version 1.24 of the extremely helpful code, here: (pages 3,4,5)
I'm also working on some better LPF and BPF (ordered several kits) and expect to write Part2 for the next issue of that section newsletter....with photos and schematics of the upgrades some of you have proposed.? ?
Gordon KX4Z
From: [email protected] <[email protected]> on behalf of radiomanjwt <jwtitmus@...>
Sent: Thursday, November 9, 2017 10:16 PM To: [email protected] Subject: Re: [BITX20] 80 Meters on BITX40? ?
I have done some more tests with a spectrum analyser, and measured the following levels with a 470pf cap across L7 in the LPF, and a 470pf cap from the left side of L1 to the right side of L3 in the BPF.
See the attached pic, I have used 2 relays, one for the LPF, and one for the BPF. 3.660 +35dbm (5w) 7.320 +10dbm (10mw) 10.980 +10dbm (10mw) 14.640 +2dbm (1.5mw) 18.300 -2dbm 21.960 -7dbm and so on. Without the cap mod on the LPF I was getting +27dbm out on 40 metres when transmitting on 80! I agree it is not optimal, but it is a lot better than trying to use the unmodified 40m LPF. |
