Neutralization... I need a good primer.

[ke7trp]

Two of us had that problem with the tube. We suggested it, He said that was not the problem.

C

[WU2D]

Whether you do it forward or backward, the technique works because it is a bridge circuit. Just make sure that you have 50 Ohms across the output connector if you use an RX or Scope on the output, and do it forward.

I like the backward method because the generator is naturally Low Z and a scope or lightly coupled receiver is naturally high Z. So I hook the gen to the output and scope to the grid.

The "generator" can be a single 2n3904 transistor oscillator with a crystal for the purposes of this test. Link couple off the tank into a 100 ohm pot and attach the tap to a pad to a SO239 connector to set your level.  This will give you a variable output with a 50 Ohm impedance. Here is a simple circuit. Got any crystals?

Mike WU2D

[KM1H]

I like the backward method because the generator is naturally Low Z and a scope or lightly coupled receiver is naturally high Z. So I hook the gen to the output and scope to the grid.

Most vintage service grade signal generators are a completely unknown output impedance and with most attempting to offer some sort of match into 300 Ohm and higher receivers. The impedance varies widely (wildly with some into the 1000 Ohm + range) with frequency.  With those driving forward into the amp minimizes or eliminates the issue.

Carl
KM1H

 

[KX5JT]

Well I gave my VFO a good cleaning and used some contact cleaner on various areas.  It's much more stable up on 10 meters now.  My grid current behaves.  The DX-60 loads a whole differently up there and of to get clean audio and a nice envelop I have to sacrifice a lot of power.  So a few watts into the SB-200 which also suffers quite a bit on gain up on 10 meters yeilds about 35 to 45 watts of clean resting carrier with good swing to about 150 watts p.e.p.  This isn't too bad actually because when 10 is open it doesn't take much to put out a respectable signal.  At least I now have the advantage of the modified DX-60 audio and bandwidth.  The TS-570 sounds good but it is 2.4Khz TX (on ssb) so that's a pretty restricted 4.8 khz on AM.  It's very high quality communications audio but the DX-60 is closer to 6.5 or 7 Khz before rolling off.  Much more pleasant to copy.

I appreciate the tips and I will still seek an rf signal generator for the bench at the Orange, TX and Rayne, LA hamfests coming a few weeks.

73 from the marsh praries of South Louisiana
John KX5JT

[ke7trp]

Good job.. Sounds like you got it going. Sounds like my VF1. It just needed some cleaning and a new cord. 

C