[Fwd: LF: Frequency stability]

[Andre' Kesteloot]

Dick Rollema wrote:

> To All from PA0SE A simple system combining the
> flexibility of a VFO with the stability of a quartz
> crystal is a V FO + "Huff and Puff" frequency stabiliser.
> This device frequency-locks the VFO to the nearest one of
> a series of frequencies that increase in steps of for
> instance 32Hz and are derived from a crystal. Take for
> instance a VFO in the 8MHz range and a stabiliser with
> 32Hz raster. When divided by 64 down to 136kHz the
> frequency steps become 0.5Hz. After manually tuning the
> VFO the frequency creeps towards the nearest raster point
> which is never more than 0.25Hz away and it stays
> there. When a crystal at room temperature is not good
> enough a TCXO could be used. The "Huff and Puff" system
> was designed by the late Klaas Spaargaren, PA0KSB and
> described in many articles in among others RadCom and Ham
> Radio. Also in my copy of X-Mozilla-Status: 0009at Hawkers
> Amateur Radio Techniques and possibly in later editions as
> well.Mike, G3XDV, publications manager of RSGB, can no
> doubt tell you more about this. I use a "Huff and Puff"
> stabiliser on the VFO of my valved HF-band transmitter and
> it functions exactly as expected. I would certainly add
> one to the 8MHz VFO of my LF-band transmitter if I were to
> use QRSS. For normal CW the VFO in itself is stable
> enough. 73, Dick, PAoSE