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Recently I had occasion to have to rebuild THREE ?power supply units ( located under the chassis) of the Commander line of amps. ?Two HF2500’s and one? VHF2000. ?Both use the same power supply

PROBLEM SOLVED. I feel like hurting someone.? ?The Relays contacts are in parallel!!!!!!!!!!!!!!!!! WTF??????????????????? ?Its 6 terminals. The part number is CORRECT on the relay and

This board does not use band pass networks. My friend ran them through and found they are only low pass chebychev Filters. He sent me the graphs. I can post them tomorrow. This board is only low pass

Update. I got a good measurement and found the 40 toroid 1.8uh.? ?Way to much.? Why??? It's 13 turns of 20 on a t68-2 core. I removed about half.? 7 turns.? ?Measured 1.1. This is much better.

##? ur making a mountain out of a mole hill.? Just a 50 ohm resistor on the output..... and any mfj-259B / favourite analyzer of the week/ VNA will work.? Or a? xcvr feeding 10-50 watts? into the

Ok,? I just checked my own manually tuned, tuned input, which cover 160-15m.? Tuned for 3750 khz, (1:1 sq swr) ,? swr rises at 4 mhz...and also 3.5 mhz.? And rises even more the further I go below

I ran the board into a dummy load with an FT450. It shows flat with relay off in pass through. Engaged it shows 1.0 with Trimmers at zero. Any attempt to adjust the caps from zero raises SWR. Even

One added note for LP filters....like used on the output of SS amps.? The harmonics don't get absorbed by the LP filter, nor are they routed to grnd.? ?They get reflected by towards the final PA.

I don't get it.? Sure, the PI network is a LP filter.? BUT when tweaked for? 1:1? swr at the middle of a band, the swr rises when u go below / above the band edges. I'm gonna re-check this in the

Peter. This is NOT a band pass filter?? I am confused here.? I expected each band slot to have a band pass for that band and a cut off above and below. What I see is that I can adjust the match to

Yes, a real easy way to tell is to look at the transfer function with omega equal 0. A non mathematical way is simply, if you put DC in will you get DC out? 73 – Mike Mike B. Feher, N4FS 89 Arnold

Yes,those are 5 turns. A pi-filter with capacitors as shunt elements is a low pass filter, not a band pass filter. Differences from the instructions to the real world might be caused by stray and

So this would be 5? I have tried 7, 6 and 5 turns. NO band pass. Only a cut off past 40mhz. As I remove turns I require less and less cap on each side. With this winding it's 0pf on each side. If I

If a wire goes through the center of a toroid, it counts and acts as a turn. It does not need to be looped around. 73 - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 Sent:

I removed 2 turns and still do not see band pass. What I see is a high pass at 40mhz. Below that it's pretty flat down the bands. It's supposed to be 7 turns of 20awg. Do the wire ends as they loop

## I design and run the PI tuned inputs through software every other week...then verify on the

I got all the parts in and am building the board. I installed all the relays, the 10 meter A and B trimmers and the wound a toroid. 7 turns of 20 AWG With a dummy load on output of 50 ohms and the

The resonating oil cap value is easily measured with any digital lcr meter. The real problem is measuring the choke.? I went through this with dahl / hammond a couple of years ago. A standard digital

160 Meter Coil Installation, Paralleled Band Switch Contacts etc. Here the? 10 uh,? 160m coil is finally installed.....made from 1/4" tubing. Bandswitch contacts have been paralleled.? Taps to

I have found at least 1/2 oz specs for RG-393..... and they are all over the map.? ?393 only has a? small 12 ga center conductor.....(.0808").? The issue is....whatever the puny center conductor