The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

The best antenna is one that is resonant on the frequency you want to TX/RX on and that suits your requirements (mobile, base, directional, compact, etc etc etc ?)

Bit late with the reply :oops: but I found some pics of a four element quad mid build and some of the four element loop driven yagi hoisted aloft! http://i1117.photobucket.com/albums/k593/swoodcock1/Quad3_zps0e55f344.jpg http://i1117.photobucket.com/albums/k593/swoodcock1/IMG00028_zps8a13b8da.jpg ht...

Great job HomerBB

I had an Avanti Sigma IV back in the day (circa 1980) & worked the world on 12w ssb

Last home-brew for me was a four-element loop driven array - I'll post some pictures when I get time.

Keep up the good work

Hammer sorted - just need the anvil!

Did you ever manage to perfect that mod for 5kc steps on the Grant by the way - seemed like much better idea than fiddling around with the clarifier & a frequency counter to get the zero's

Quite correct Dave - glad you're paying attention at the back! =D> You'll find that the extra inductance will also give you more downward shift than up & you'll need to reset the VCO offsets (& probably find that you can't align it correctly with the Coarse control in the center notch positi...

This reply is obviously a bit late but may help someone else.

Try adding a 5.6uH coil in series to 0v end of the varactor diodes

Thanks for the additional info Norm It's working very well but I can hear a very slight buzz (which stops when I touch the mic plug) on another receiver :| The other thing I noticed is a trimmer inside the mic (not the gain control which can be adjusted via a hole in the back of the mic) Anyone shed...

No Dave,

Checked the voltages & all seemed to be in order.

I've ordered some of those large cap varicap diodes (25-500pF) & will let you know how I get on.

Steve

It's the black front version Dave (with both coarse & fine) but the coarse only moves 2kc either way.

Cheers Dave

I tried it last night without the mod & the charge from the capacitor died after about five seconds!

CQ DX CQ DX CQ DX CQ DX .....................

zodiac wrote:Steve,
D44 is for Mid and Hi bands, you have unlocked the clarifier haven't you ?.
Dave.

I didn't realize it needed unlocking tbh Dave

How do I do that exactly (I have my claw-hammer & oxy-acetylene torch at the ready!)

Cheers

Steve

That's because they are, I said D1 is on the crystal board, I didn't say D4 was as well. Dave. That's me on the naughty step (again!) :oops: Okay, swapped D1 from the Xtal board on the Concorde into the Grant (D44 position) & it's just the same (all three bands) I know that one diode is used fo...

I've just got a K40 compression microphone & was thinking of wiring it up to the Cobra 148 GTL-DX Will the voltage of the switching line (approx. 3.6v on my Cobra) be enough to charge the capacitor inside the mic? I seem to remember some sort of 'power conversion' kit being supplied with the ori...

Dave,

On the Xtal board of the Concorde 2, D1 & D4 look totally different to each other?

Steve

That's normal Steve, you have to change both the varactor diodes D40 and D44 one for each crystal to get it to shift further for the same as what's in the Cobra 148GTL DX MK2 MV201, have you got a scrap 148, if so then shame on you. You can also use two ITT410 out of a scrap Cybernet radio and that...

Of course they do Dave

I had a similar problem with a Cobra 148 It had been modified to cover extra frequencies & one of the diodes had gone - no matter how far I adjusted the pots I couldn't reach the offset frequency :doh: You didn't say if your Jumbo is modified but maybe worth checking out before starting to look ...

zodiac wrote:What MOD Steve ?.

Dave - It's a great idea using the MC145151 to get 5kc steps rather than waiting for someone to call on the zero's then calling them back!

Would it tune continuously or would it still need a 10kc shift added to get the alpha's?

Steve

Cheers Dave,

Scrap Cobra 148's - perish the thought!!!

I've got a RD16HHF1 MOFET (sealed in anti-static package) if you want to do a swap for some varactor diodes?

Steve

Dave

I wouldn't mind this mod doing to a President Grant (PC-999AE)

Will it still need a +10kHz shift adding (it's standard at the moment) or does it step 5kHz continuously after the mod?

Cheers

Steve

Radio Make and Model: President Grant (Black Front) PCB Number: PC999AE PLL Number: Test gear available: Stand Alone Counter, Digital VOM Symptoms: Coarse clarifier control doesn't shift 5kc either side. What is working: Everything else works fine. What has been tried: Nothing (I'm just a keen hobby...

Dave/Ray I checked TP2 voltage on Hi band (Ch40 AM mode) & it was 7.4v I adjusted L18 for 5.4v (Hi Band CH20 AM Mode) & base voltage has dropped to 7.1v Re-checked final & driver bias (both within spec at 51ma) Hope I'm going in the right direction??? Sounds okay on my other receiver (bu...

Dave

Checked driver & final base (mike gain fully anticlockwise on SSB) & I get 0.73v & 0.69v on TX

Steve

Checked screws - all tight & solder tabs all intact. Noticed that the problem seems to occur on Hi Band setting only (especially noticable when the 'bleep' goes off - it is distinctly 'bubbly' and not a stable tone) but I'll need to get this confirmed by another station listening to the audio on...

Radio Make and Model: Cobra 148 GTL DX PCB Number: 010AA PLL Number: Test gear available: Digital VOM, Stand Alone Counter, Symptoms: Audio on SSB is distorted (like I'm gargling with gravel) What is working: Everything else is fine. What has been tried: Checked biasing, checked offset adjustments, ...