[Boatanchors] SSB Generation - Phasing VS Filter Opinion Sought

[Bill Cotter]

Scott,

I am primarily a CW/AM OP with limited experience 
in SSB, so take this opinion with that in mind.

I can tell you from some previous QSO's that 
there is a dramatic difference in fidelity and 
presence to the voice of operators using a 
Hallicrafters HT-32 (crystal filter) and a HT 37 
(phasing method), with the latter more pure and 
pleasing. Of course, this is not a blind test on 
my part, but for the same mic, the HT-37 sound 
better to me. On the otherhand, the HT-32 is MUCH better looking, HI!

If I were building a phasing-type exciter, I 
would shy away from the 50-60 year old B&W 
phasing-modules, and construct my own from 
precision-matched parts. The phasing network is 
the most critical element to get right, and 
perhaps the most fun to design and construct. The 
audio transformers might be a bit difficult to 
find, but a junker HT-37, CE-20A, SB-10 or some 
other donor set might be a good source of parts.

73 Bill N4LG



At 11:03 PM 7/18/2019, Whitebear1122 wrote:
>I am close to finishing up my homebrew 12 tube 
>dual conversion superheterodyne receiver.  I’m 
>listening to 40m cw right now and it sounds 
>great.  I plan to add some filtering to narrow 
>up the bandwidth for cw and SSB, then either put 
>it in a commercial case or build a plexiglass 
>case.  I’ve started thinking about the next 
>project which will be a CW/SSB transmitter. 
>I’m thinking tubes, at least 80m, 40m, and 
>20m, with 1 or 2 6146’s in the final.  I’ve 
>been learning about both phase and filter SSB 
>generators and I’m trying to sort out 
>advantages of both. Based on my current thinking 
>(which is sketchy at best), I’m thinking that 
>filter SSB is the better choice for me.  While 
>it appears to have a higher cost over phasing 
>due to the cost of a mechanical filter and 
>crystals, I get the impression that it has much 
>higher carrier suppression, and I don’t have 
>to build a phasing network or find an old B&W 
>phasing network.  On the other hand, both 
>methods are successfully used by commercial ham 
>transmitter mfgr's so I suppose one can’t go 
>wrong with either method. I’d appreciate 
>hearing your opinion on filter vs phasing.  Has 
>anyone on here built their own SSB transmitter 
>in the past? Many thanks, 73 Scott WA9WFA 
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