It does not make a material impact on the transmitted bandwidth in my testing.? I certainly would be interested to see if someone else has looked at the transmit bandwidth on their units.? Maybe there is something wrong with my HT-32A.

Regarding CR2, that seems more of a leveling action and has no sharpness by way of roll off at all.? And per 7-16 Crystal Filter Alignment item 3, it says "transmitter output should not drop BELOW 3dB at the extremes of the audio passband (650-3Khz).? My claim is that there is no mechanism in the rig that provides a meaningful roll off above 3 Khz beyond a small number of dB per octave.

The measurements I published on the reflector May 10 2023 had this data:

8.7K @ -12 dB from peak amplitude (yellow trace)

6.8K @ -12 dB from peak amplitude (green trace)

So yes, there is a roll off.? But from a crystal BPF standpoint, the HT-32A I measured is really really wide by comparison.? I would be very interested in someone else making a similar measurement on their rig for a sanity check.?

-- 
73/jeff/ac0c
alpha-charlie-zero-charlie

73/jeff/ac0c
alpha-charlie-zero-charlie

CR2 is the passband filter. Its adjustment is C121.

Walt Cates, WD0GOF

?

A majority of acceptance is not proof of correctness.

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From:?[email protected] <[email protected]> on behalf of Jeff AC0C <keepwalking188@...>
Sent:?Tuesday, April 2, 2024 11:53 AM
To:?[email protected] <[email protected]>
Subject:?Re: [HallicraftersRadios] HT-32 filters

?

That's true Walt.? But if you sweep these filters, they don't provide passband attenuation on the transmitted sideband.? They do a fine job on the carrier and the opposite sideband, but don't do anything for the occupied bandwidth of the transmitted signal.

I actually could not believe this was the case - and to that end, completely disassembled the filter modules on a spare HT-32 I had to check out what the SA was showing me.? I have plots & photos of that exercise around here somewhere if someone is interested.?

73/jeff/ac0c
alpha-charlie-zero-charlie

On 4/2/2024 11:22 AM, waltcates wrote:

The 32 actually has 3 filters CR2, FL1 and FL2?

Walt Cates, WD0GOF

?

A majority of acceptance is not proof of correctness.

---

From: [email protected] <[email protected]>?on behalf of Jeff AC0C <keepwalking188@...>
Sent:?Tuesday, April 2, 2024 10:56 AM
To: [email protected] <[email protected]>
Subject:?Re: [HallicraftersRadios] SR 150

?

The HT-32 has no BPF in the classic sense.? Just some L/C type providing a pretty gentle roll off.?

73/jeff/ac0c
alpha-charlie-zero-charlie

On 4/2/2024 10:48 AM, Rick W4XA wrote:

The Drake TR-4 came with 2.1 kHz filters.? I replaced them in mine with the aftermarket Inrad 2.5kHz filters.

Not only do I get much better reports on the air but the receive fidelity is a LOT easier to listen to!
I get great audio reports with my HT-32B.? I think it's got a 3kHz filter in it?


I couldn't find the filter specs in the SR-400 manual.? I guess they really don't say what the BW? is. but it would seem to be somewhere around 2.3-2.5 kHz based on the shift in the carrier frequencies?? I guess the only way to know for sure would be to "sweep" it.


--
73/Rick
W4XA
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