Rick, That was the only option I could come up with that met the observed symptoms! However, I dismissed it because I didn't think enough of the 5MHz-5.5MHz PTO signal would make it through the MC149
I'm surprised the LO filter can be peaked as low down in frequency as 5.5MHz. The schematic I'm looking at has fixed 10pF capacitors across T1 secondary and primary which means they are about 7uH whe
The filter _isn't_ peaked on 20m - the balanced mixer and the filter are bypassed on 20m and the 5-5.5MHz is injected directly into the LO buffer. Steve G3TXQ
I'm new to this discussion, so if the following point has already been made I apologise: Link-coupled tuners do _not_ inherently provide good common-mode current rejection. If the design includes a g
Paul, Tom, W8JI, made the same comment a few years ago; however I've seen these coil sets being made in the FCO manufacturing facility. Of course the design could have simply been copied from the BC-
That's not what antenna modelling tells us. For example an 80m horizontal half-wave over average ground has over 7dB more loss at a height of 10ft than it does at 50ft, even though in both cases the
A couple of observations: 1) It would benefit from an effective ferrite-cored choke balun at the input rather than the narrowband air-cored balun that he suggests. 2) Apart from the balun, the CM per
Jon, One other check you might want to make while Q6 is removed: on Rx, measure the voltage at the R32/R33 junction, and the voltage at the R31/R32 junction; they should be around 1.7v and 9.5v respe
And when you want to switch between a variety of transmitters and open-wire-fed antennas, simply use a multi-way open-wire switch like the one here: http://www.bbceng.info/Operations/transmitter_ops/
The first thing I'd do is check that R33 is not open-circuit, or has become disconnected at one end or the other. Steve G3TXQ On 19/10/2015 22:40, jon greenwood via TenTec wrote: Update on Corsair: r
Joe, A possible explanation - and from my experience the most likely one - is that your "antenna" was actually the braid of your coax, top-loaded by the OCF wire. The differential-mode impedance of a
Some time ago I made an inventory of all the parts in my CorsairII and PSU, excluding regular resistors and capacitors. I was able to source spares of everything except the programmed MC68705P3 micro
Just one observation on switchable baluns - don't do it the way Elecraft does it! They take two separate 1:1 current baluns and connect their inputs in parallel; then they connect their outputs in se
Be careful using those "additional loss due to SWR" tables; in some circumstances the unmatched cable loss can be *less* than its matched loss. Steve G3TXQ
At HF the losses in most transmission lines are copper losses, not dielectric losses; so the losses are directly proportional to the square of the current. Picture the current standing wave along a m
Bob, Another typical application where this stuff matters is a multiband doublet fed with ladderline. For convenience a lot of folk terminate the ladderline at a balun outside the shack, and then use
From IEEE Standard Definitions of Terms for Antennas: "2.102 dipole antenna. Any one of a class of antennas producing a radiation pattern approximating that of an elementary electric dipole. Syn: dou
Agreed! It also discredits the notion that: "Any center fed straight wire is a dipole, regardless of how it's length compares the the wavelength you are using it on." Steve G3TXQ N6KB