Re: Harmonics and Relay Replacement
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Thanks Gary! I had not thought to try mounting them on the bottom of the board so there would be a ground plane shield between the relay and other wiring. ?I just did that and ran the tests again. ?Unfortunately they were NOT encouraging.? The only improvement was the 40 meter third harmonic. ?In all other cases, both the 2nd and 3rd harmonics were worse with the relays on the bottom rather than the top of the uBITX main board. ?They did, however remain in spec with the worst case being the 3rd harmonic of 40 meters. This one was marginally better on the bottom but none of the others benefitted from the change. Results with the relays on the bottom of the board vs on the top. ?Same uBITX used for the original tests, I just carefully moved the relays to the bottom. ?Not going to move them again, but will put the new relays back on top of the 2nd V4 board later today. Jim Sheldon, W0EB 80 meters? 2nd harmonic ?-62.1 dBC ?vs -65.7 dBC - bottom worse 3rd harmonic -58.4 dBC vs -76.4 dBC ?- bottom worse 30 meters - not tested today 40 meters? 2nd harmonic -56.2 dBC vs ?-58.0 dBC - bottom worse 3rd harmonic -51.7 dBC vs -47.2 dBC - bottom better 20 meters 2nd harmonic - 57.5 dBC vs -65.2 dBC - bottom worse 3rd harmonic - -52.6 dBC vs -64.8 dBC - bottom worse 17 meters not tested yesterday so not tested with relays on top of the board. 2nd harmonic -53.1 dBC 3rd harmonic -61 dBC ??
------ Original Message ------
From: "Gary Anderson" <gary.ag5tx@...>
Sent: 10/11/2018 9:34:14 AM
Subject: Re: [BITX20] Harmonics and Relay Replacement Hi Jim, |
Jim Sheldon