All,
I know this isn't the right forum for this - anybody know of
a forum for people building linear amps?
Last night, I had my first contact in some years. A pleasant gentleman in Calgary. Unfortunately, he could not hear me as well as
I heard him, and we had to cut it short. So frustrating! I was reminded of why we have linear amps. I was running barefoot, 100W.
So this morning, I hauled the 30L-1 out of the shed. Oh my aching back! The 30L-1 is a 60's vintage Collins linear with 4 811-A tubes.
It's big. It's heavy. It does Not Belong in this bedroom.
I'm looking forward to building the LDMOS amp that I ordered on Ebay.
Also looking forward to the uBITX transceiver.
For me, ham radio is about two things - building equipment, and chatting about building equipment :).
- Jerry KF6VB
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On 2021-04-11 07:50, Evan Hand wrote:
Jerry,
I did do the testing of my modified v4 against my unmodified v5. I
have posted the power levels of the v4 on this thread. The IMD
measurements that I got are as follows:
Modified v4:
80meters: -21db
40meters: -19db
20meters: -20db
Unmodified v5:
80meters: -22db
40meters: -21db
20meters: -19db
As far as I can tell there is not really much difference in the SSB
performance with the change of C81 to 2670pF.
The only comment that I would make is that overall the IMD3
performance is not what I would like. Another 5 to 6 dB would have
been better.
Harmonics were down 51db for both rigs. I did not test for the spur
on the v4.
Harmonic tests were done with a TinySA connected through a homebrew
50db tap and a step attenuator.
IMD3 tests were done with an RSP1A and the RSP-Spectrum Analyzer
program using the same connections.
At this point, I do not plan to modify my v6 as CW is not a mode I
use. Also, I have other rigs that excel at QRP CW that I would use
instead. So my conclusion is to make the mod IF you want the CW
capability. It does not make sense if you are using SSB.
73
Evan
AC9TU
Links:
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[1] /g/BITX20/message/87545
[2] /mt/81780486/243852
[3] /g/BITX20/post
[4] /g/BITX20/editsub/243852
[5] /g/BITX20/leave/10189903/243852/952924773/xyzzy
